FIELD
[0001] The subject matter described herein relates to the field of copper production, and
more particularly relates to an automatic charging apparatus for a furnace.
BACKGROUND
[0002] In conventional production process of copper and copper alloy tubes, sheets, and
strips with a horizontal continuous casting furnace, it is always needed to charge
an appropriate amount of zinc feedstock to condition zinc content of the molten copper
in the furnace so as to ensure product quality of continuous casting. In the prior
art, a certain amount of zinc feedstock is first weighed and then manually charged
into the furnace. During this process, an operator has to endure the high temperature
inside the furnace; in addition, charging of the zinc feedstock is also labor intensive.
Therefore, the conventional zinc feedstock charging manner is unfriendly to operators.
SUMMARY
[0003] To overcome the above and other drawbacks of manually charging feedstock into a furnace
in conventional technologies, embodiments of the disclosure provide an automatic charging
apparatus for a furnace, which can implement automatic charging of feedstock in the
furnace, thereby reducing labor intensity of operators and realizing accurate control
the amount of feedstock charged.
[0004] The disclosure adopts a technical solution below:
An automatic charging apparatus for a furnace comprises:
a hopper provided with an inlet opening and an outlet opening;
a buffer bin in which a buffer channel is provided, one end of the buffer channel
being provided with a discharge port communicating with the outlet opening, another
end of the buffer channel being in communication with a feeding inlet of a furnace;
a pushing mechanism configured to push feedstock in the buffer channel sequentially
into the feeding inlet of the furnace, the pushing mechanism comprising a drive and
a pushing element, the drive driving the pushing element to perform a reciprocating
movement in the buffer channel such that the feedstock in the buffer channel is sequentially
pushed into the feeding inlet via the reciprocating movement of the pushing element.
[0005] In the technical solution above, the feedstock to be charged into the furnace may
be first inputted into the hopper via the inlet opening. The feedstock in the hopper
may sequentially enter the buffer channel via the outlet opening, and then the pushing
mechanism sequentially pushes the feedstock in the buffer channel into the feeding
inlet; each reciprocal movement of the pushing element allows for pushing a certain
amount of feedstock; by controlling the number of times of the reciprocal movement
of the pushing element, the amount of feedstock to be charged may be accurately controlled.
Since the mass of each piece of feedstock is substantially consistent, this solution
may realize accurate control of the amount of the feedstock charged. In addition,
by controlling the speed of reciprocal movement of the pushing element, the charging
speed of the feedstock may be controlled such that the feedstock may be charged into
the furnace at a constant speed or at a set timing and quantity required by a process.
[0006] Preferably, a storage channel is inclinedly provided in the buffer bin, the storage
channel being disposed above the buffer channel, an upper end of the storage channel
being in communication with the outlet opening, a lower end of the storage channel
being in communication with the buffer channel.
[0007] In the technical solution above, a certain amount of feedstock may be stored in the
storage channel so as to increase the amount of pre-stored feedstock.
[0008] Preferably, a plurality of the storage channels are provided, the plurality of storage
channels being successively arranged in a vertical direction; and in two neighboring
storage channels, the lower end of the storage channel above is in communication with
the upper end of the storage channel below. This technical solution may further increase
the amount of pre-stored feedstock.
[0009] Preferably, a cavity of the buffer bin is in communication with a cavity of the furnace;
a plurality of through holes are provided in an inner wall of the buffer channel and/or
an inner wall of the storage channel such that high-temperature gas in the furnace
accesses the buffer channel and/or the storage channel in the buffer bin.
[0010] In the technical solution above, the high-temperature gas in the furnace may access
the buffer bin and then enter the buffer channel and the storage channels via the
through holes, such that the high-temperature gas may preheat the feedstock in the
buffer bin; in this way, heat of the high-temperature gas discharged from the inside
of the furnace may be sufficiently recycled, which saves energy; in addition, preheating
of the feedstock may reduce the melting time of the feedstock in the furnace, thereby
enhancing production efficiency.
[0011] Preferably, a bottom surface of one end of the buffer channel proximal to the feeding
inlet is provided with a limiting block, an inclined surface being provided on the
limiting block, the inclined surface tilting from one side proximal to the feeding
inlet toward one side distant from the feeding inlet such that the feedstock is pushed
by the pushing element to move toward the feeding inlet along the inclined surface
and cross over the limiting block into the feeding inlet.
[0012] In the technical solution above, when the pushing element extends out, it may push
the feedstock in the buffer channel to cross over the inclined surface into the feeding
inlet; the amount of the feedstock entering the feeding inlet is associated with an
extended length of the pushing element; the remaining feedstock in the buffer channel,
which has not been pushed into the feeding inlet yet, may be stopped by the limiting
block from rushing into the feeding inlet due to inertance.
[0013] Preferably, the pushing element is disposed below the discharge port, the bottom
surface of the buffer channel tilting from the side distant from the feeding inlet
to the side proximal to the feeding inlet, a tilt angle of the bottom surface of the
buffer channel being smaller than a tile angle of the inclined surface such that when
the pushing element is retracted, the feedstock in the buffer channel is retained
in the buffer channel.
[0014] In the technical solution above, the tilting arrangement of the bottom surface of
the buffer channel from the side distant from the feeding inlet to the side proximal
to the feeding inlet allows for the feedstock in the buffer channel to move toward
the feeding inlet, such that when the pushing element is retracted, backward movement
of the feedstock along with the pushing element may be avoided, such that the feedstock
in the hopper or storage channels may smoothly fall into the buffer channel.
[0015] Preferably, the pushing element is disposed below the discharge port, the buffer
channel comprising a forward tilting segment and backward tilting segment, the forward
tilting segment being disposed at a side proximal to the pushing mechanism, the backward
tilting segment being disposed at a side proximal to the feeding inlet, a bottom surface
of the forward tilting segment tilting from a side distant from the feeding inlet
to a side proximal to the feeding inlet, a bottom surface of the backward tilting
segment tilting from a side proximal to the feeding inlet toward a side distant from
the feeding inlet.
[0016] In the technical solution above, the tilting arrangement of the bottom surface of
the forward tilting segment from the side distant from the feeding inlet to the side
proximal to the feeding inlet allows for the feedstock in the forward tilting segment
to move towards the feeding inlet, such that when the pushing element is retracted,
backward movement of the feedstock may be prevented, and the feedstock in the hopper
or the storage channel may smoothly fall into the buffer channel. The tilting arrangement
of the bottom surface of the backward tilting segment from the side proximal to the
feeding inlet toward the side distant from the feeding inlet may prevent the feedstock
in the backward tilting segment, which has not been pushed into the feeding inlet
yet, from rushing into the feeding inlet due to inertance when the pushing element
extends out, and may also prevent the feedstock in the backward tilting segment from
rolling into the feeding inlet when the pushing element is retracted.
[0017] Preferably, the pushing element is disposed below the discharge port; a height of
an upper end surface of the pushing element relative to the bottom surface of the
buffer channel is h1, and a height of the feedstock in the buffer channel relative
to the bottom surface of the buffer channel is h2, h2≥h1, such that when the pushing
element extends out, the feedstock above the buffer channel at least partially enters
the buffer channel and contacts the upper end surface of the pushing element.
[0018] In the technical solution above, when the pushing element extends out, it may push
the feedstock in the buffer channel into the feeding inlet. Meanwhile, the feedstock
above the pushing element will enter the buffer channel via the discharge port and
contacts the upper end surface of the pushing element, such that when the pushing
element is retracted, the feedstock already falling on the pushing element may block
backward rolling of the feedstock in the buffer channel, and after the pushing element
is retracted, the feedstock on the pushing element may move downward continuously
under gravity and contacts the bottom surface of the buffer channel, thereby completing
charging.
[0019] Preferably, h2≥2h1. This solution enables the feedstock above the pushing element
to fall into the buffer channel as much as possible when the pushing element extends
out, which enhances the blocking effect of the feedstock above the pushing element
with respect to the feedstock in the buffer channel.
[0020] Preferably, the pushing mechanism comprises a first drive, a second drive, a first
pushing element, and a second pushing element, the first drive driving the first pushing
element to perform a reciprocating movement in the buffer channel, the second drive
driving the second pushing element to perform a reciprocating movement in the buffer
channel, the first pushing element and the second pushing element being arranged in
juxtaposition below the discharge port, a height of an upper end surface of the second
pushing element relative to the bottom surface of the buffer channel being h3, a height
of the feedstock in the buffer channel relative to the bottom surface of the buffer
channel being h2,; when pushing the feedstock, the first pushing element and the second
pushing element extend out simultaneously, such that after the feedstock in the buffer
channel is completely pushed, the first pushing element is retracted first, such that
the feedstock above the buffer channel at least partially enters the buffer channel
and contacts the upper end surface of the second pushing element.
[0021] In the technical solution above, the height of the first pushing element is close
to that of the feedstock. In a case of a need to charge the feedstock, the first pushing
element and the second pushing element extend out simultaneously, which may push the
feedstock in the buffer channel into the feeding inlet, and then the first pushing
element is retracted while the second pushing element maintains stationary; this may
prevent rolling-back of the feedstock in the buffer channel while allowing for the
feedstock above the buffer channel to at least partially enter the buffer channel
and contact the upper end face of the second pushing element; then, the second pushing
element is retracted, and the feedstock on the second pushing element may continuously
move downward under the gravity and contact the bottom surface of the buffer channel,
thereby completing the charging.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022]
Fig. 1 is a structural schematic diagram of the disclosure;
Fig. 2 is a structural schematic diagram of an automatic feedstock charging apparatus
according to the disclosure;
Fig. 3 is a local enlarged view of part A in Fig. 2;
Fig. 4 is a structural schematic diagram of a third example embodiment of the disclosure;
Fig. 5 is a first structural schematic diagram of a fifth example embodiment of the
disclosure;
Fig. 6 is a second structural schematic diagram of the fifth example embodiment of
the disclosure;
Fig. 7 is a structural schematic diagram of a sixth example embodiment of the disclosure;
Fig. 8 is a structural schematic diagram of a pushing mechanism in the sixth example
embodiment of the disclosure;
Fig. 9 is a structural schematic diagram of a metal melting furnace including a stirring
device when a stirring disc is lowered in a seventh example embodiment of the disclosure;
Fig. 10 is a structural schematic diagram of the metal melting furnace including a
stirring device when the stirring disc is lifted in the seventh example embodiment
of the disclosure;
Fig. 11 is a top view of the metal melting furnace including a stirring device in
the seventh example embodiment of the disclosure;
Fig. 12 is a top view of the stirring disc in the seventh example embodiment of the
disclosure;
Fig. 13 is a sectional view of the stirring disc in the seventh example embodiment
of the disclosure;
Fig. 14 is a sectional view of the stirring disc when feedstock is charged into a
feedstock inlet in the seventh example embodiment of the disclosure;
Fig. 15 is a sectional view of the stirring disc when the feedstock enters the cavity
in the seventh example embodiment of the disclosure;
Fig. 16 is a sectional view of the stirring disc when the feedstock rolls below the
first opening in the seventh example embodiment of the disclosure;
Fig. 17 is a sectional view of the stirring disc before being immersed in the molten
metal in the seventh example embodiment of the disclosure;
Fig. 18 is a sectional view of the stirring disc immersed in the molten metal in the
seventh example embodiment of the disclosure;
Fig. 19 is a structural schematic diagram of the automatic charger and the stirring
device in the seventh example embodiment of the disclosure.
[0023] Reference Numerals: furnace 100; chamber 110; feeding inlet 101; stirring disc 200;
feedstock inlet 201; stirring rod 210; disc body 220; annular boss 230; drainage port
240; outer-ring wall 250; third opening 260; circular space 270; inner-ring wall 280;
radial opening 290; drive device 300; lifting power element 310; rotating power element
320; splined sleeve 330; feedstock holding portion 400; cavity 410; first opening
420; second opening 430; baffle plate 440; automatic charging apparatus 500; hopper
570; inlet opening 571; outlet opening 572; closure 573; buffer bin 580; buffer channel
581; forward tilting segment 581.1; backward tilting segment 581.2; discharge port
581.3; storage channel 582; through hole 583; pushing mechanism 590; drive 591, first
drive 591.1, second drive 591.2, pushing element 592, first pushing element 592.1;
second pushing element 592.2; limiting block 584; inclined surface 585; feedstock
800.
DETAILED DESCRIPTION
[0024] Hereinafter, the disclosure will be described in further detail through example embodiments
with reference to the accompanying drawings.
Example Embodiment 1:
[0025] Figs. 1 and 2 illustrate an automatic charging apparatus for a furnace, comprising:
a hopper 570, a buffer bin 580, and a pushing mechanism 590, the hopper 570 comprising
an inlet opening 571 and an outlet opening 572, a buffer channel 581 being provided
in the buffer bin 580, one end of the buffer channel 581 being provided with a discharge
port 581.3 communicating with the outlet opening 572, the other end of the buffer
channel 581 being in communication with a feeding inlet 101 of the furnace 100; the
pushing mechanism 590 is configured to push feedstock 800 in the buffer channel 581
sequentially into the feeding inlet 101 of the furnace 100, the pushing mechanism
590 comprising a drive 591 and a pushing element 592, the drive 591 driving the pushing
element 592 to move reciprocally in the buffer channel 581 such that the feedstock
800 in the buffer channel 581 is sequentially pushed into the feeding inlet 101 via
reciprocal movement of the pushing element 592.
[0026] In the technical solution above, the feedstock 800 to be charged into the furnace
100 may be first inputted into the hopper 570 via the inlet opening 571; the inputting
of the feedstock 800 into the hopper 570 may be done manually or automatically via
a mechanical device. The feedstock 800 in the hopper 570 may sequentially enter the
buffer channel 581 via the outlet opening 572, and then the pushing mechanism 590
sequentially pushes the feedstock 800 in the buffer channel 581 into the feeding inlet
101; each reciprocal movement of the pushing element 592 allows for pushing a certain
amount of feedstock 800; by controlling the number of times of the reciprocal movement
of the pushing element 592, the amount of feedstock 800 to be charged may be accurately
controlled. Since the mass of each piece of feedstock 800 is substantially consistent,
this solution may realize accurate control of the amount of the feedstock 800 charged.
In addition, by controlling the speed of reciprocal movement of the pushing element
592, the charging speed of the feedstock 800 may be controlled such that the feedstock
800 may be charged into the furnace 100 at a constant speed. The drive 591 is fixed
on an outer sidewall of the buffer bin 580, the pushing element 592 being slidingly
connected to the buffer bin 580.
[0027] Preferably, a plurality of storage channels 582 are further inclinedly provided in
the buffer bin 580, the plurality of storage channels 582 being successively arranged
in a vertical direction, and in two neighboring storage channels 582, a lower end
of the upper storage channel 582 is in communication with an upper end of the lower
storage channel 582; the lowermost storage channel 582 is disposed above the buffer
channel 581, the upper end of the uppermost storage channel 582 is in communication
with the outlet opening 572, and the lower end of the lowermost storage channel 582
is in communication with the buffer channel 581.
[0028] In the technical solution above, a certain amount of feedstock 800 may be stored
in the storage channels 582 so as to increase the amount of pre-stored feedstock 800.
[0029] Preferably, a cavity of the buffer bin 580 is in communication with a cavity of the
furnace 100; a plurality of through holes 583 are provided on an inner wall of the
buffer channel 581 and on inner walls of the storage channels 582, such that high-temperature
gas in the furnace 100 can access the buffer channel 581 and the storage channels
582 in the buffer bin 580.
[0030] In the technical solution above, the high-temperature gas in the furnace 100 may
access the buffer bin 580 and then enter the buffer channel 581 and the storage channels
582 via the through holes 583, such that the high-temperature gas may preheat the
feedstock 800 in the buffer bin 580; in this way, heat of the high-temperature gas
discharged from the inside of the furnace 100 may be sufficiently recycled, which
saves energy; in addition, preheating of the feedstock 800 may reduce the melting
time of the feedstock in the furnace 100, thereby enhancing production efficiency.
The buffer bin 580 is provided with a gas discharging port for discharging the high-temperature
gas.
[0031] It is understood that in an implementation, a closure 573 detachably connected to
the hopper 570 is provided on the hopper 570, such that the closure 573 has a closed
state for closing the inlet opening 571 and an open state for opening the inlet opening
571. The closure 573 may close the inlet opening 571 when no feedstock 800 is to be
charged into the hopper 570, avoiding discharge of the high-temperature gas via the
inlet opening 571. The detachable connection may refer to buckling, snap-fitting,
and bolt fastening, etc.
[0032] It is understood that, in another implementation, a closure 573 hinged to the hopper
570 is provided on the hopper 570 such that the closure 573 has a closed state for
closing the inlet opening 571 and an open state for opening the inlet opening 571.
The closure 573 may close the inlet opening 571 when no feedstock 800 is to be charged
into the hopper 570, avoiding discharge of the high-temperature gas via the inlet
opening 571.
[0033] It is understood that, in an implementation, the drive 591 is a linear drive, the
linear drive driving the pushing element 592 to perform a linear reciprocal movement
in the buffer channel 581.
[0034] It is understood that, in another implementation, the drive may be a rotary drive,
e.g., an electric motor, one end of the pushing element being fixed to the rotary
drive, the rotary drive driving the pushing element to sway reciprocally, whereby
the feedstock is pushed into the feeding inlet.
Example Embodiment 2
[0035] As illustrated in Figs. 1 to 3, based on the first example embodiment, a limiting
block 584 is fixed to a bottom surface of one end of the buffer channel 581 proximal
to the feeding inlet 101, an inclined surface 585 being provided on the limiting block
584, the inclined surface 585 facing the feedstock 800 in the buffer channel 581,
the inclined surface 585 tilting from the side proximal to the feeding inlet 101 toward
the side distant from the feeding inlet 101 such that the feedstock 800 can be pushed
by the pushing element 592 to move toward the feeding inlet 101 along the inclined
surface 585 and cross over the limiting block 584 into the feeding inlet 101.
[0036] In the technical solution above, when the pushing element 592 extends out, it may
push the feedstock 800 in the buffer channel 581 to cross over the inclined surface
585 into the feeding inlet 101; the amount of the feedstock 800 entering the feeding
inlet 101 is associated with an extended length of the pushing element 592; the remaining
feedstock 800 in the buffer channel 581, which has not been pushed into the feeding
inlet 101 yet, may be stopped by the limiting block 584 from rushing into the feeding
inlet 101 due to inertance.
[0037] Preferably, the pushing element 592 is disposed below the discharge port 581.3, a
bottom surface of the buffer channel 581 tilting toward the direction of the feeding
inlet 101 from top to down, a tilt angle of the bottom surface of the buffer channel
581 being smaller than that of the inclined surface 585 such that when the pushing
element 592 is retracted, the feedstock 800 in the buffer channel 581 is retained
in the buffer channel 581.
[0038] In the technical solution above, the feedstock 800 in the buffer channel 581 may
move toward the feeding inlet 101, such that when the pushing element 592 is retracted,
backward movement of the feedstock 800 along with the pushing element 592 may be avoided,
such that the feedstock 800 in the storage channels 582 may smoothly fall into the
buffer channel 581.
Example Embodiment 3
[0039] As illustrated in Fig. 4, based on Example Embodiment 1, the pushing element 592
is disposed below the discharge port 581.3, the buffer channel 581 comprising a forward
tilting segment 581.1 and a backward tilting segment 581.2, the forward tilting segment
581.1 being disposed at a side proximal to the pushing mechanism 590, the backward
tilting segment 581.2 being disposed at a side proximal to the feeding inlet 101,
a bottom surface of the forward tilting segment 581.1 tilting toward the direction
of the feeding inlet 101 from top to down, a bottom surface of the backward tilting
segment 581.2 tilting toward the direction of the feeding inlet 101 from down to top.
[0040] In the technical solution above, the tilting arrangement of the bottom surface of
the forward tilting segment 581.1 toward the direction of the feeding inlet 101 from
top to down allows for the feedstock 800 in the forward tilting segment 581.1 to move
toward the feeding inlet 101, which may prevent the feedstock 800 to move backward
when the pushing element 592 is retracted, such that the feedstock 800 in the storage
channels 582 may smoothly fall into the buffer channel 581. The tilting arrangement
of the bottom surface of the backward tilting segment 581.2 toward the feeding inlet
101 from down to top may prevent the feedstock 800 in the backward tilting segment
581.2, which has not been pushed into the feeding inlet 101 yet, from rushing into
the feeding inlet 101 due to inertance when the pushing element 592 extends out and
may also prevent the feedstock 800 in the backward tilting segment 581.2 from rolling
into the feeding inlet 101 when the pushing element 592 is retracted.
[0041] In this example embodiment, the forward tilting segment 581.1 and the backward tilting
segment 581.2 may be connected directly or via a horizontal segment which is horizontally
disposed.
Example Embodiment 4
[0042] Based on the Example Embodiment 1, the bottom surface of the buffer channel tilts
toward the feeding inlet from down to top. This arrangement may prevent the feedstock
in the buffer channel from rolling into the feeding inlet.
Example Embodiment 5
[0043] As illustrated in Figs. 5 and 6, based on Example Embodiment 1, the pushing element
592 is disposed below the discharge port 581.3; a height of an upper end surface of
the pushing element 592 relative to the bottom surface of the buffer channel 581 is
h1 and a height of the feedstock in the buffer channel 581 relative to the bottom
surface of the buffer channel 581 is h2, h2≥h1, such that when the pushing element
592 extends out, the feedstock 800 above the buffer channel 581 at least partially
enters the buffer channel 581 and contacts the upper end surface of the pushing element
592.
[0044] When the pushing element 592 extends out, the feedstock 800 below the discharge port
581.3 will be pushed forward, and the foremost feedstock 800 in the buffer channel
581 will fall into the feeding inlet 101; while when the pushing element 592 is retracted,
the feedstock 800 rolls back till under or below the discharge port 581.3 along with
the pushing element 592, and the rolling-back feedstock 800 will block the feedstock
800 above the discharge port 581.3 from falling off, such that the feedstock 800 above
the discharge port 581.3 cannot fall into the buffer channel 581 and is stuck at the
discharge port 581.3; as a result, no feedstock 800 will be replenished into the buffer
channel 581, and thereafter, when the pushing element 592 extends out again, since
the buffer channel 581 has no new feedstock 800 replenished, there will be no feedstock
800 to be pushed from the buffer channel 581 into the feeding inlet 101, such that
the automatic charging apparatus cannot charge the feedstock in an accurate and smooth
manner. In this example embodiment, when the pushing element 592 extends out, it may
push the foremost feedstock 800 in the buffer channel 581 into the feeding inlet 101.
Meanwhile, the feedstock 800 above the pushing element 592 will partially enter the
buffer channel 581 via the discharge port 581.3 and contact the upper end surface
of the pushing element 592, such that when the pushing element 592 is retracted, the
feedstock 800 already falling on the pushing element 592 may block backward rolling
of the feedstock 800 in the buffer channel 581, and after the pushing element 592
is retracted, since the feedstock 800 on the pushing element 592 has been at least
partially located in the buffer channel 581, it is not easily stuck by the feedstock
in the buffer channel 581; in this way, the feedstock 800 on the pushing element 592
may move downward continuously under gravity and contact the bottom surface of the
buffer channel 581, thereby completing charging.
[0045] Preferably, h2≥2h1. This solution enables the feedstock 800 above the pushing element
592 to fall into the buffer channel 581 as much as possible when the pushing element
592 extends out, which enhances the blocking effect of the feedstock 800 above the
pushing element 592 with respect to the feedstock 800 in the buffer channel 581, such
that the feedstock 800 above the discharge port 581.3 may enter the buffer channel
581 more smoothly.
[0046] In this example embodiment, in order to prevent the feedstock 800 in the buffer channel
581 from rolling into the feeding inlet 101 before the pushing element 592 pushes
the feedstock 800, the bottom surface of the buffer channel 581 tilts toward the direction
of the feeding inlet 101 from down to top.
Example Embodiment 6
[0047] As illustrated in Figs. 7 and 8, based on Example Embodiment 1, the pushing mechanism
590 comprises a first drive 591.1, a second drive 591.2, a first pushing element 592.1,
and a second pushing element 592.2, the first drive 591.1 driving the first pushing
element 592.1 to perform a reciprocating movement in the buffer channel 581, the second
drive 591.2 driving the second pushing element 592.2 to perform a reciprocating movement
in the buffer channel 581, the first pushing element 592.1 and the second pushing
element 592.2 being disposed in juxtaposition below the discharge port 581.3, a height
of the second pushing element 592.2 being lower than that of the first pushing element
592.1, where the height of the upper end surface of the second pushing element 592.2
relative to the bottom surface of the buffer channel 581 is h3 and the height of the
feedstock 800 in the buffer channel 581 relative to the bottom surface of the buffer
channel 581 is h2, 3h3≤h2≤4h3; when pushing the feedstock, the first pushing element
592.1 and the second pushing element 592.2 simultaneously extend out; after the feedstock
800 in the buffer channel 581 is completely pushed, the first pushing element 592.1
is retracted first, such that the feedstock 800 above the buffer channel 581 at least
partially enters the buffer channel 581 and contacts the upper end face of the second
pushing element 592.2.
[0048] When the pushing element 592 extends out, the feedstock 800 below the discharge port
581.3 will be pushed forward, and the foremost feedstock 800 in the buffer channel
581 will fall into the feeding inlet 101; while when the pushing element 592 is retracted,
the feedstock 800 rolls back till under or below the discharge port 581.3 along with
the pushing element 592, and the rolling-back feedstock 800 will block the feedstock
800 above the discharge port 581.3 from falling off, such that the feedstock 800 above
the discharge port 581.3 cannot fall into the buffer channel 581 and is stuck at the
discharge port 581.3; as a result, no feedstock 800 is replenished into the buffer
channel 581, and thereafter, when the pushing element 592 extends out again, since
the buffer channel 581 has no new feedstock 800 replenished, there will be no feedstock
800 to be pushed from the buffer channel 581 into the feeding inlet 101, such that
the automatic charging apparatus cannot charge the feedstock in an accurate and smooth
manner. In this example embodiment, in a case of a need to charge the feedstock, the
first pushing element 592.1 and the second pushing element 592.2 extend out simultaneously,
which may push the foremost feedstock 800 in the buffer channel 581 into the feeding
inlet 101, and then the first pushing element 592.1 is retracted while the second
pushing element 592.2 maintains stationary; this may prevent rolling-back of the feedstock
800 in the buffer channel 581 while allowing for the feedstock 800 above the buffer
channel 581 to at least partially enter the buffer channel 581 and contact the upper
end face of the second pushing element 592.2; at which time, the part of feedstock
800 having fallen into the buffer channel 581 may block rolling-back of the feedstock
800 previously disposed in the buffer channel 581; then, the second pushing element
592.2 is retracted; since the feedstock 800 on the second pushing element 592.2 has
been partially located in the buffer channel 581, it is not easily stuck by the feedstock
in the buffer channel 581; therefore, the feedstock 800 on the second pushing element
592.2 may continuously move downward under the gravity and contact the bottom surface
of the buffer channel 581, thereby completing the charging.
[0049] In this example embodiment, simultaneous extension of the first pushing element 592.1
and the second pushing element 592.2 may ensure that the feedstock 800 in the buffer
channel 581 is pushed into the feeding inlet 101, while after the first pushing element
592.1 and the second pushing element 592.2 extend out, it is only needed to limit
the feedstock 800 in the buffer channel 581 to prevent its backward-rolling, without
a need to provide a power for pushing the feedstock 800. Therefore, the second pushing
element 592.2 may be disposed lower in height. In some implementations, h3≤h2/3, namely
3h3≤h2. Lower height of the second pushing element 592.2 allows for enough feedstock
800 above the buffer channel 581 to fall into the buffer channel 581 after the first
pushing element 592.1 is retracted, which can block the feedstock 800 falling into
the buffer channel 581 from rolling back, and ensures the feedstock 800 to completely
fall into the buffer channel 581 after the second pushing element 592.2 is retracted.
If the second pushing element 592.2 is arranged too low, the feedstock 800 in the
buffer channel 581 might roll till above the pushing element 592, unable to block
backward-rolling of the feedstock 800; therefore, in order to guarantee the blocking
effect, it is needed to provide a certain height for the second pushing element 592.2,
which, in some implementations, may be h2/4≤ h3, i.e., h2^4h3.
[0050] Furthermore, the height of the first pushing element 592.1 is h4, h4≥ h2/2, which
ensures that the first pushing element 592.1 may smoothly push the feedstock 800 in
the buffer channel 581 to move forward. In some implementations, the height of the
first pushing element 592.1 is equal to that of the feedstock 800.
[0051] In this example embodiment, in order to prevent the feedstock 800 in the buffer channel
581 from rolling into the feeding inlet 101 before the pushing element 592 pushes
the feedstock 800, the bottom surface of the buffer channel 581 tilts toward the direction
of the feeding inlet 101 from down to top.
Example Embodiment 7
[0052] Figs. 1 to 18 illustrate a metal melting furnace including a stirring device, comprising
a furnace 100 and a stirring device, the furnace 100 defining a chamber 110 for accommodating
molten metal, the stirring device being configured to sufficiently mix feedstock charged
into the chamber 110 with the molten metal such that the feedstock is homogeneously
distributed in the molten metal. The stirring device comprises a stirring disc 200,
a stirring rod 210 connected to the stirring disc 200, and a drive device 300 in drive
connection to the stirring rod 210, the stirring disc 200 having a feedstock holding
portion 400, the drive device 300 being configurable to drive the stirring rod 210
to move up and down such that the stirring disc 200 is immersed in or lifted out of
the molten metal in the chamber 110, a plurality of vertically through opening being
provided on the stirring disc 200 such that during the stirring process, the feedstock
in the feedstock holding portion 400, along with the stirring disc 200, is immersed
in the molten metal in which the feedstock is melted, the drive device 300 being configured
to drive the stirring rod 210 to lift reciprocally.
[0053] According to the disclosure, during the smelting process of the metal melting furnace
including a stirring device, the feedstock charged into the molten metal can be held
on the stirring disc 200 via the feedstock holding portion 400, such that the feedstock,
along with the stirring disc 200, may be immersed into the molten metal, without floating
on top of the molten metal, which prevents oxidization reaction and abnormal loss
of the feedstock due to being exposed to the air in a high-temperature environment;
in addition, this design can also increase oxygen content in the molten metal, and
prevents inhomogeneous composition distribution of the molten metal due to floating
of the feedstock on top of the molten metal or sinking of the feedstock to the bottom
of the molten metal. The stirring rod 210 is configurable to lift reciprocally under
the action of the drive device 300, such that the stirring disc 200 moves up and down
in the molten metal, which may enhance homogeneity of the feedstock in the molten
metal, thereby ensuring consistent quality of metal products; in addition, this design
eliminates a need of manual stirring, reduces labor intensity of operators, and lowers
risks. Moreover, automated stirring offers a larger stirring range than manual stirring
and avoids the quality issue arising from insufficient stirring in some areas of the
molten metal, which also gives a higher stirring efficiency than manual operation.
[0054] The vertically through openings allow for the molten metal to pass through the stirring
disc 200, which reduces the resistance subjected to the stirring disc 200 when moving
up and down in the molten metal and avoids extensive diffusion of bottom-layer impurities
caused by the induced vortex of the molten metal, such that the molten metal may flow
gently during up-and-down movement of the stirring disc 200. Generally, extensive
impurities would be deposited at the bottom layer of molten metal; the molten metal
at the bottom layer does not participate in the casting process, but always resides
in the melting furnace till the furnace is scrapped. In the disclosure, since the
stirring disc 200 carrying the feedstock does not induce extensive diffusion of the
impurities during the melting process, the quality of the molten metal available for
casting in the chamber 110 will not be affected; in addition, it takes less time for
letting the stirred molten metal stand till the impurities settle, without incurring
unnecessary energy waste; and meanwhile, the disclosure may enhance smelting efficiency
of the molten metal and thus improve productivity.
[0055] In the disclosure, the molten metal refers to molten copper, and the feedstock refers
to zinc; alternatively, the feedstock may be other elements or compounds, and the
molten metal may also be molten iron, molten steel, etc.
[0056] Since the molten metal is rapidly cooled down when being exposed to the air, it is
improper to design a movable part on the stirring disc 200 to hold the feedstock;
in addition, after the feedstock size is shrunk, it becomes unholdable. Referring
to Figs. 12 to 18, based on the example embodiments described
supra, in one implementation of the disclosure, the feedstock holding portion 400 defines
a cavity 410 for accommodating the feedstock, and the openings comprise a first opening
420 provided in the top wall of the cavity 410 and a second opening 430 provided in
the bottom wall of the cavity 410, the first opening 420 and the second opening 430
having a size smaller than that of the feedstock; during the stirring process, the
molten metal may access the cavity 410 via the first opening 420 and the second opening
430, where it is sufficiently mixed with the feedstock. Then, the molten metal mixed
with the feedstock composition flows out of the cavity 410 via the first opening 420
and the second opening 430 to be mixed with external molten metal, whereby the feedstock
is sufficiently distributed in the molten metal. Since the sizes of the first opening
420 and the second opening 430 are smaller than that of the feedstock, the feedstock
can be kept in the cavity 410; with the feedstock being melt, its size is shrunk to
be smaller than that of the first opening 420 and that of the second opening 430,
such that it likely escapes from the stirring disc 200 via the first opening 420 and
the second opening 430; however, since the shrunk size of the feedstock is very small,
even if it floats on top of the molten melt or sinks to the bottom of the molten melt,
it has little impact on the composition of molten metal; in addition, if the molten
metal has a higher melting point, the feedstock will be completely melted before floating
on top of the molten metal or sinking to the bottom of the molten metal.
[0057] In addition, a feedstock inlet 201 in communication with the cavity 410 is provided
on an upper surface of the stirring disc 200, such that the feedstock may be replenished
into the cavity 410 via the feedstock inlet 201. The size of the feedstock inlet 201
is slightly greater than that of the feedstock. In an example implementation, a ratio
of the size of the feedstock inlet 201 to the size of the feedstock ranges from 11/10
to 6/5. With this design, it becomes more difficult for the feedstock to leave the
cavity 410 via the feedstock inlet 201.
[0058] Furthermore, the bottom wall of the cavity 410 has a height gradually reduced from
the feedstock inlet 201 toward the direction of the first opening 420. In the disclosure,
the feedstock is a spherical object, which, after being charged into the cavity 410
via the feedstock inlet 201, may move, under its own gravity, till beneath the first
opening 420 along the bottom wall of the cavity 410; in this way, if the feedstock
has a density greater than that of the molten metal, the feedstock can be kept at
the bottom wall of the cavity 410 without entering the molten metal via the feedstock
inlet 201 during up-and-down movement of the stirring disc 200; if the feedstock has
a density smaller than that of the molten metal, the feedstock will float up to abut
against the top wall of the cavity 410 after the stirring disc 200 is immersed in
the molten metal, in which case since the floating feedstock is located beneath the
first opening 420, it does not easily enter the molten metal via the feedstock inlet
201.
[0059] Referring to Figs. 13 to 18, based on the example embodiments described
supra, in one implementation of the disclosure, the feedstock holding portion 400 further
comprises a baffle plate 440, the baffle plate 440 being formed as extending from
the cavity 410 between the feedstock inlet 201 and the first opening 420 toward the
bottom wall of the cavity 410, both sides of the baffle plate 440 being connected
to the sidewall of the cavity 410. In a case that the density of the feedstock is
lower than that of the molten metal, the feedstock will move upward after the stirring
disc 200 is immersed in the molten metal; the baffle plate 440 serves to baffle the
upward floating feedstock and limit the feedstock from moving toward the feedstock
inlet 201. The feedstock before floating upward is located in the cavity 410 offset
from the feedstock inlet 201; since the surface of the molten metal flows gently,
the feedstock's upward floating follows a substantially vertically linear course,
such that it does not easily move toward the direction of the feedstock inlet 201
during the upward floating process; even if the upward floating feedstock has a tendency
of moving toward the feedstock inlet 201, it will be baffled and stopped by the lower
end of the baffle plate 440 after floating upward a certain height, thereby avoiding
the circumstance that the feedstock is separated from the stirring disc 200 during
the process of immersing the stirring disc 200 in the molten metal. In addition, since
both sides of the baffle plate 440 are connected to the sidewall of the cavity 410,
the feedstock cannot bypass the baffle plate 440 to move toward the feedstock inlet
201.
[0060] Referring to Fig. 13, as a further technical solution, the baffle plate 440 tilts
from top to down toward the direction of the feedstock inlet 201; the tilting design
of the baffle plate 440 improves the feedstock baffling range of the lower end of
the baffle plate 440, which may enhance the feedstock baffling performance of the
lower end of the baffle plate 440 and thus may improve reliability.
[0061] The minimal interval between the lower end of the baffle plate 440 and the top wall
of the cavity 410 is R1, the diameter of the feedstock is R2, R1<6/5R; with this design,
the feedstock may be baffled by the baffle plate 440 after moving upward a small height.
[0062] Referring to Fig. 19, based on the embodiments described
supra, in one implementation of the disclosure, the drive device 300 comprises a lifting
power element 310 and a rotating power element 320, a splined sleeve 330 fitting with
the stirring rod 210 being sleeved over the stirring rod 210, the rotating power element
320 being configured to drive the splined sleeve 330 to rotate. Due to the splined-fitting
between the stirring rod 210 and the splined sleeve 330, the splined sleeve 330 does
not limit up-and-down movement of the stirring rod 210 relative to the splined sleeve
330. The lifting power element 310 is configurable to generate a power driving the
stirring rod 210 to move up and down, allowing for the stirring disc 200 to be immersed
in or lifted out of the molten metal or allowing for the stirring disc 200 to move
up and down in the molten metal; the rotating power element 320 is configurable to
drive the splined sleeve 330 to rotate, such that the splined sleeve 330 drives the
stirring disc 200 to rotate in the molten metal, enhancing feedstock homogeneity in
the molten metal.
[0063] Referring to Figs. 12 through 18, based on the embodiments described
supra, in one implementation of the disclosure, a plurality of feedstock holding portions
400 are provided on the stirring disc 200, the plurality of the feedstock holding
portions 400 being arranged at intervals along a circumferential direction of the
stirring disc 200. Provision of the plurality of feedstock holding portions 400 allows
for more feedstock to be carried by the stirring disc 200, which eliminates a need
of frequent replenishment of feedstock. By arranging the feedstock holding portions
400 at intervals along the circumference of the stirring disc 200, feedstock can be
replenished to different parts of the molten metal, such that the feedstock is homogeneously
melted in the molten metal without incurring intensive fluctuation or flow of the
molten metal.
[0064] Referring to Figs. 13 through 19, based on the embodiments described
supra, in one implementation of the disclosure, the stirring disc 200 comprises a disc body
220 connected to the stirring rod 210 and an annular boss 230 disposed at the bottom
of the disc body 220, the height of the upper surface of the disc body 220 being gradually
reduced from the stirring rod 210 to the periphery. The upper surface of the disc
body 220 serves to guide the molten metal such that when the stirring disc 200 moves
upward, the molten metal in the direction of the stirring disc 200 may be guided by
the upper surface of the disc body 220 to flow toward the periphery of the disc body
220, which can reduce the magnitude of stirring the molten copper, and during the
process of the stirring disc 200 exiting the molten metal, the molten metal left on
the upper surface of the stirring disc 200 may be reduced so as to prevent the cooled
molten metal from blocking the openings.
[0065] A drainage port 240 through the lower surface of the stirring disc 200 is provided
at the intersection between the bottom wall of the cavity 410 and the sidewall of
the cavity 410 proximal to the second opening 430. During the process of the stirring
disc 200 exiting the molten metal, a part of the molten metal in the cavity 410 may
be drained via the second opening 430 at the bottom wall of the cavity 410, and the
remaining part of the molten metal flows along the bottom wall of the cavity 410 toward
the sidewall of the cavity 410, converges there, and is drained via the drainage port
240; this may reduce the amount of molten metal left on the stirring disc 200.
[0066] An outer-ring wall 250 of the annular boss 230 is connected to the periphery of the
disc body 220. The openings further comprise a third opening 260, the third opening
260 being located at a position on the disc body 220 corresponding to a circular space
270 enclosed by the annular boss 230, the bottom end of the annular boss 230 being
connected to its outer-ring wall 250 via a conical surface, the bottom end of the
annular boss 230 being connected to the top wall of the circular space 270 also via
a conical surface, such that the lower end of the annular boss 230 is shrunk from
top to down, while the circular space 270 is gradually flared from top to down.
[0067] The annular boss 230 protrudes from the bottom of the disc body 220, such that during
the process of immersing the stirring disc 200 in the molten metal, the annular boss
230 first accesses the molten metal prior to the disc body 220; since the lower end
of the annular boss 230 is tapered, the annular boss 230, during the process of being
immersed in the molten metal, generates a reduced intensity in stirring the molten
metal, without incurring intensive fluctuation in the molten metal. The outer-ring
wall 250 of the annular boss 230 is connected to the periphery of the disc body 220,
such that the periphery of the disc body 220 does not protrude from the annular boss
230, which reduces the molten metal stirring magnitude at its peripheral portion during
the process of immersing the disc body 220 in the molten metal, avoiding formation
of a vortex around the stirring disc 200. When the annular boss 230 is completely
immersed into the molten metal, the lower surface of the disc body 220 corresponding
to the circular space 270 enclosed by the annular boss 230 contacts the molten metal,
while provision of the third opening 260 allows for the molten metal to pass through
the third opening 260, further reducing the molten metal stirring magnitude of the
stirring disc 200. In addition, provision of the circular space 270 can also reduce
the overall weight of the stirring disc 200, thereby reducing the load of the drive
device 300. The sidewall of the circular space 270 serves to guide the molten metal,
which can reduce the molten metal stirring magnitude of the lower surface of the disc
body 220 corresponding to the circular space 270.
[0068] A radial opening 290 communicating with the cavity 410 is further provided on the
inner-ring wall 280 and the outer-ring wall 250 of the annular boss 230 so as to facilitate
circulation of the molten metal in the cavity 410.
[0069] Referring to Fig. 12 through Fig. 18, based on the example embodiments described
supra, in one implementation of the disclosure, a plurality of groups of third openings
are provided on the top wall of the circular space 270, each group of the third openings
comprising a plurality of third openings 260, the plurality of third openings 260
in each group of third openings being disposed along the circumferential direction
of the stirring disc 200, as illustrated in Fig. 12. Fig. 12 illustrates two groups
of third openings disposed on the stirring disc 200, one group thereof including three
third openings 260, the other group thereof including six third openings 260. Among
the plurality of groups of third openings, the height of the top wall of the circular
space 270 around one group of the third openings is higher than the remaining portions
of the top wall of the circular space 270, such that during the process of immersing
the stirring disc 200 into the molten metal, the gas in the circular space 270 is
discharged via that group of third openings, and also during the descending process
of the stirring disc 200, the gas in the circular space 270 is discharged via the
third openings 260.
[0070] Based on the example embodiments described
supra, in one implementation thereof, the metal melting furnace including a stirring device
further comprises an automatic charging apparatus 500 configured to replenish feedstock
to the feedstock holding portion 400, where the automatic charging apparatus 500 may
adopt any solution described in Example Embodiment 1 through Example Embodiment 6.
The feedstock inlet 201 on the stirring disc 200 is aligned to the feeding inlet 101,
such that the feedstock 800 charged by the automatic charging apparatus 500 into the
feeding inlet 101 enters the feedstock inlet 201. The rotating power element 320 drives
the stirring disc 200 to rotate intermittently to replenish the feedstock to each
feedstock holding portion 400. The automatic charging apparatus 500 allows for automatic
replenishment of the feedstock to the stirring disc 200, which eliminates manual charging,
thereby enhancing operation safety as well as operation efficiency. Since a plurality
of feedstock holding portions 400 are arranged on the stirring disc 200, during the
feedstock replenishing process, the rotating power element 320 drives the stirring
disc 200 to rotate to switch the feedstock holding portions 400 to be aligned to the
automatic charging apparatus 500, whereby the feedstock is replenished to each feedstock
holding portions 400 one by one. During the charging process, the stirring disc 200
rotates intermittently, providing sufficient time for charging; at this point, the
stirring disc 200 and the automatic charging apparatus 500 are relatively still, avoiding
offset when the feedstock drops off.
1. An automatic charging apparatus for a furnace, comprising:
a hopper (570) provided with an inlet opening (571) and an outlet opening (572);
a buffer bin (580) in which a buffer channel (581) is provided, one end of the buffer
channel (581) being provided with a discharge port (581.3) communicating with the
outlet opening (572), another end of the buffer channel (581) being in communication
with a feeding inlet (101) of a furnace (100);
a pushing mechanism (590) configured to push feedstock (800) in the buffer channel
(581) sequentially into the feeding inlet (101) of the furnace (100), the pushing
mechanism (590) comprising a drive (591) and a pushing element (592), the drive (591)
driving the pushing element (592) to perform a reciprocating movement in the buffer
channel (581) such that the feedstock (800) in the buffer channel (581) is sequentially
pushed into the feeding inlet (101) via the reciprocating movement of the pushing
element (592).
2. The automatic charging apparatus for a furnace according to claim 1, wherein a storage
channel (582) is inclinedly provided in the buffer bin (580), the storage channel
(582) being disposed above the buffer channel (581), an upper end of the storage channel
(582) being in communication with the outlet opening (572), a lower end of the storage
channel (582) being in communication with the buffer channel (581).
3. The automatic charging apparatus for a furnace according to claim 2, wherein a plurality
of the storage channels (582) are provided, the plurality of storage channels (582)
being successively arranged in a vertical direction; and in two neighboring storage
channels (582), the lower end of an upper storage channel (582) is in communication
with an upper end of a lower storage channel (582).
4. The automatic charging apparatus for a furnace according to claim 2, wherein a cavity
of the buffer bin (580) is in communication with a cavity of the furnace (100); a
plurality of through holes (583) are provided in an inner wall of the buffer channel
(581) and/or an inner wall of the storage channel (582) such that high-temperature
gas in the furnace (100) accesses the buffer channel (581) and/or the storage channel
(582) in the buffer bin (580).
5. The automatic charging apparatus for a furnace according to any one of claims 1 to
4, wherein a bottom surface of one end of the buffer channel (581) proximal to the
feeding inlet (101) is provided with a limiting block (584), an inclined surface (585)
being provided on the limiting block (584), the inclined surface (585) tilting from
one side proximal to the feeding inlet (101) toward one side distant from the feeding
inlet (101) such that the feedstock (800) is pushed by the pushing element (592) to
move toward the feeding inlet (101) along the inclined surface (585) and cross over
the limiting block (584) into the feeding inlet (101).
6. The automatic charging apparatus for a furnace according to claim 5, wherein the pushing
element (592) is disposed below the discharge port (581.3), the bottom surface of
the buffer channel (581) tilting from the side distant from the feeding inlet (101)
to the side proximal to the feeding inlet (101), a tilt angle of the bottom surface
of the buffer channel (581) being smaller than a tilt angle of the inclined surface
(585) such that when the pushing element (592) is retracted, the feedstock (800) in
the buffer channel (581) is retained in the buffer channel (581).
7. The automatic charging apparatus for a furnace according to any one of claims 1 to
4, wherein the pushing element (592) is disposed below the discharge port (581.3),
the buffer channel (581) comprising a forward tilting segment (581.1) and backward
tilting segment (581.2), the forward tilting segment (581.1) being disposed at a side
proximal to the pushing mechanism (590), the backward tilting segment (581.2) being
disposed at a side proximal to the feeding inlet (101), a bottom surface of the forward
tilting segment (581.1) tilting from a side distant from the feeding inlet (101) to
a side proximal to the feeding inlet (101), a bottom surface of the backward tilting
segment (581.2) tilting from a side proximal to the feeding inlet (101) toward a side
distant from the feeding inlet (101).
8. The automatic charging apparatus for a furnace according to any one of claims 1 to
4, wherein the pushing element (592) is disposed below the discharge port (581.3);
a height of an upper end surface of the pushing element (592) relative to the bottom
surface of the buffer channel (581) is h1, and a height of the feedstock (800) in
the buffer channel (581) relative to the bottom surface of the buffer channel (581)
is h2, h2≥h1, such that when the pushing element (592) extends out, the feedstock
(800) above the buffer channel (581) at least partially enters the buffer channel
(581) and contacts the upper end surface of the pushing element (592).
9. The automatic charging apparatus for a furnace according to claim 8, wherein h2≥2h1.
10. The automatic charging apparatus for a furnace according to any one of claims 1 to
4, wherein the pushing mechanism (590) comprises a first drive (591.1), a second drive
(591.2), a first pushing element (592.1), and a second pushing element (592.2), the
first drive (591.1) driving the first pushing element (592.1) to perform a reciprocating
movement in the buffer channel (581), the second drive (591.2) driving the second
pushing element (592.2) to perform a reciprocating movement in the buffer channel
(581), the first pushing element (592.1) and the second pushing element (592.2) being
arranged in juxtaposition below the discharge port (581.3), a height of an upper end
surface of the second pushing element (592.2) relative to the bottom surface of the
buffer channel (581) being h3, a height of the feedstock (800) in the buffer channel
(581) relative to the bottom surface of the buffer channel (581) being h2, 3h3 ≤ h2
≤ 4h3; when pushing the feedstock (800), the first pushing element (592.1) and the
second pushing element (592.2) extend out simultaneously, such that after the feedstock
in the buffer channel (581) is completely pushed, the first pushing element (592.1)
is retracted first, such that the feedstock (800) above the buffer channel (581) at
least partially enters the buffer channel (581) and contacts the upper end surface
of the second pushing element (592.2).