Technical Field
[0001] A mode of the present invention relates to a shot processing device.
Background Art
[0002] Patent Literature 1 discloses a shot processing device provided with a shot processing
jig (1) having a cage (24), jig rotation holding means (3) for rotationally holding
the shot processing jig (1), a projection chamber body (2) for sealing the jig rotation
holding means (3), a projecting device (7) for projecting a projection material, and
projection material circulating means (8) for recovering the projected projection
material and supplying it to the projecting device (7).
Citation List
Patent Literature
[0003] Patent Literature 1: Japanese Patent Application Publication No.
2010-82727
Summary of Invention
Technical Problem
[0004] However, in a shot processing device provided with this type of shot processing jig,
reduction of the overall height of the entire device is in demand.
[0005] In this technical field, a shot processing device whose overall height of the entire
device can be reduced is in demand.
Solution to Problem
[0006] A shot processing device according to an aspect of the present invention is provided
with a cabinet formed having a box shape and having a projection material projection
area therein, a rotary hanger having a turntable arranged rotatably in a horizontal
direction inside the cabinet, a plurality of partition materials provided on the turntable
and dividing a space on the turntable into a plurality of parts in a circumferential
direction of the turntable, and a plurality of hangers provided on each of a plurality
of chambers divided by the plurality of partition materials and each suspending and
holding a work or a cage into which the work is inserted, a revolution driving motor
configured to rotate the rotary hanger so as to sequentially move the plurality of
chambers to the projection material projection area in the cabinet, a rotation driving
motor configured to rotate the hanger provided in the chamber located in the projection
material projection area among the plurality of chambers, a projector configured to
apply shot processing to the work by projecting the projection material to the chamber
located in the projection material projection area among the plurality of chambers
from outside in the radial direction of the turntable, a first projection material
conveying mechanism configured to recover the projection material projected from the
projector and convey the projection material in the horizontal direction, and a plurality
of second projection material conveying mechanisms configured to convey the projection
material conveyed by the first projection material conveying mechanism upward.
[0007] According to this shot processing device, since a plurality of the second projection
material conveying mechanisms configured to convey the projection material upward
are provided, each second projection material conveying mechanism can be reduced in
size in the height direction. As a result, the overall height of the entire device
can be reduced.
[0008] In an embodiment, the shot processing device may be further provided with a third
projection material conveying mechanism configured to convey the projection material
conveyed by the plurality of second projection material conveying mechanisms in the
horizontal direction, a first projection material tank and a second projection material
tank configured to store the projection material conveyed by the third projection
material conveying mechanism, a level sensor configured to detect an amount of the
projection material stored in the second projection material tank, a balance tank
provided in parallel with the projector, and a switching mechanism configured to have
the projection material supplied from the first projection material tank to the balance
tank when a detected value of the level sensor exceeds a specified value set in advance,
and configured to have the projection material supplied from the balance tank to the
first projection material conveying mechanism while having the projection material
supplied from the second projection material tank to the projector when the detected
value of the level sensor falls under the specified value.
[0009] According to this shot processing device, when the detected value of the level sensor
exceeds the specified value set in advance, the projection material is supplied from
the first projection material tank to the balance tank. On the other hand, when the
detected value of the level sensor falls under the above-described specified value,
the projection material is supplied from the second projection material tank to the
projector and the projection material is supplied from the balance tank to the first
projection material conveying mechanism. Therefore, a good balance can be kept in
a transport amount of the projection material without shortage of the projection material.
[0010] In the embodiment, the shot processing device may be further provided with a separator
provided between the plurality of second projection material conveying mechanisms
and the third projection material conveying mechanism and configured to perform wind
selection of the whole amount of the projection material conveyed by the second projection
material conveying mechanism and a vibration sieve vibration sieve classify a part
of the projection material conveyed by the third projection material conveying mechanism.
[0011] According to this shot processing device, the separator is provided between the plurality
of second projection material conveying mechanisms and the third projection material
conveying mechanism, and the whole amount of the projection material conveyed by the
second projection material conveying mechanism is subjected to wind selection by this
separator. Therefore, the classification performance of the projection material can
be ensured even for works producing many burrs and fine powders. Moreover, by means
of this separator, the vibration sieve classify a part of the projection material
conveyed by the third projection material conveying mechanism and a structure in which
the projection material is not projected but passed through the separator and the
vibration sieve again by storage of the projection material in the above-described
balance tank and supply of the projection material from this balance tank, the classification
performance of the projection material can be ensured.
[0012] In the embodiment, the projector may be configured to have an impeller configured
to project a projection material with rotation, a driven pulley rotatably supported
with respect to the cabinet and rotated integrally with the impeller, a driving pulley
rotated by a driving motor, a driving belt wound around the driving pulley and the
driven pulley, a rotating member rotatably supporting the driving pulley and also
rotatably supported by the cabinet capable of adjusting a distance between the driving
pulley and the driven pulley, and an expansion/contraction mechanism connecting a
rotation end portion of the rotating member and the cabinet and capable of adjusting
a length in an axial direction.
[0013] According to this shot processing device, by adjusting the length in the axial direction
of the expansion/contraction mechanism, the rotating member is rotated, whereby the
distance between the driving pulley and the driven pulley is adjusted, and a tension
of the driving belt can be adjusted. Therefore, since it is not necessary to loosen
a bolt of a mounting portion of the driven pulley into the cabinet in order to adjust
the tension of the driving belt, for example, workability can be made favorable.
[0014] In the embodiment, the partition material may be configured to have a pair of side
wall portions opposite to each other and extending in the radial direction of the
turntable, respectively, and a bottom wall portion connecting end portions on the
center side of the turntable in the pair of side wall portions and inclined toward
the center side of the turntable as it goes from one of the pair of side wall portions
to the other.
[0015] According to this shot processing device, the bottom wall portion of the partition
material is inclined toward the center side of the turntable as it goes from one of
the pair of side wall portions to the other. Therefore, even if the projection material
projected by the projector from the outside in the radial direction of the turntable
hits the bottom wall portion, bouncing of this projection material to the projection
side can be suppressed. As a result, durability of the projector can be ensured.
Advantageous Effects of Invention
[0016] As described above, according to the various aspects and the embodiment of the present
invention, the overall height of the entire device can be reduced.
Brief Description of Drawings
[0017]
[Figure 1 Figure 1 is a front view illustrating a shot processing device according
to an embodiment of the present invention.
[Figure 2] Figure 2 is a side view of the shot processing device illustrated in Figure
1.
[Figure 3] Figure 3 is a rear view of the shot processing device illustrated in Figure
1.
[Figure 4] Figure 4 is a plan view of the shot processing device illustrated in Figure
1.
[Figure 5] Figures 5 are diagrams illustrating a configuration of a centrifugal projector
illustrated in Figure 1, in which Figure 5(A) is a plan view, Figure 5(B) is a front
view, and Figure 5(C) is a side view.
[Figure 6] Figures 6 are diagrams illustrating a configuration of another centrifugal
projector illustrated in Figure 1, in which Figure 6(A) is a plan view, Figure 6(B)
is a front view, and Figure 6(C) is a side view.
[Figure 7] Figure 7 is a planar sectional view of a cabinet illustrated in Figure
1.
[Figure 8] Figure 8 is a rear view of the shot processing device (circulation portion)
illustrated in Figure 1.
[Figure 9] Figure 9 is a front view illustrating a variation of a shot processing
device according to an embodiment of the present invention.
[Figure 10] Figure 10 is a side view of the shot processing device illustrated in
Figure 9.
[Figure 11] Figure 11 is a rear view of the shot processing device illustrated in
Figure 9.
[Figure 12] Figure 12 is a plan view of the shot processing device illustrated in
Figure 9.
[Figure 13] Figures 13 are diagrams illustrating a configuration of a centrifugal
projector illustrated in Figure 9, in which Figure 13(A) is a front view and Figure
13(B) is a side view.
[Figure 14] Figures 14 are diagrams illustrating a configuration of another centrifugal
projector illustrated in Figure 9, in which Figure 14(A) is a side view and Figure
14(B) is a front view.
[Figure 15] Figure 15 is a planar sectional view of a cabinet illustrated in Figure
9.
Description of Embodiments
[0018] An embodiment of the present invention will be described below by referring to Figures
1 to 9. Figure 1 is a front view of a shot processing device 10 according to the embodiment,
and Figure 2 is a side view of the shot processing device 10 illustrated in Figure
1. As illustrated in Figures 1 and 2, the shot processing device 10 according to the
embodiment of the present invention is provided with a cabinet 12. Figure 7 is a planar
sectional view of the cabinet 12. As illustrated in Figure 7, this cabinet 12 is formed
having a box shape having a pentagonal cross section. Inside this cabinet 12, a work
carrying-in area 14 for performing carrying-in of a work W, a work carrying-out area
16 for performing carrying-out of the work W, and projection material projection areas
18A to 18D for projecting a projection material to the work W are provided.
[0019] At a center part inside this cabinet 12, a rotary hanger 20 is provided. This rotary
hanger 20 is rotated by a revolution driving motor 24 around a revolution shaft 22
extending in the vertical direction as illustrated in Figure 1.
[0020] On the revolution shaft 22, a revolution indexing device 26 and a torque limiter
28 are provided. Moreover, this revolution shaft 22 is rotatably supported by an upper
bearing 30 and a lower bearing 32.
[0021] The rotary hanger 20 includes, as illustrated in Figure 7, a turntable 34 arranged
rotatably in a horizontal direction in the cabinet 12 and a plurality of partition
materials 36 provided on this turntable 34 and dividing a space on the turntable 34
into a plurality of parts in the circumferential direction of the turntable 34.
[0022] The partition material 36 includes a pair of side wall portions 38 and a bottom wall
portion 40. The pair of side wall portions 38 are opposite to each other and extending
in the radial direction of the turntable 34, respectively. The bottom wall portion
40 connects end portions on the center side of the turntable 34 in the pair of side
wall portions 38 and are inclined toward the center side of the turntable 34 as it
goes from one of the pair of side wall portions 38 to the other.
[0023] The rotary hanger 20 is rotated by the revolution driving motor 24 (See Figure 1).
By the means of rotation, a plurality of chambers 42 divided by the above-described
plurality of partition materials 36 are moved sequentially to the work carrying-in
area 14, the work carrying-out area 16, and the projection material projection areas
18A to 18D.
[0024] That is, the chamber 42 located in the work carrying-in area 14 among the plurality
of chambers 42 is used as the work carrying-in chamber, and the chamber 42 located
in the work carrying-out area 16 among the plurality of chambers 42 is used as the
work carrying-out chamber. Moreover, the chamber 42 located in the projection material
projection areas 18A to 18D among the plurality of chambers 42 is used as the projection
chamber. As described above, the above-described plurality of chambers 42 are switched
sequentially to the work carrying-in chamber, the work carrying-out chamber, and the
projection chamber by means of rotation of the rotary hanger 20.
[0025] In this embodiment, the work W is a forging, a pressing, a welded structure and the
like, or more specifically automobile related components, for example.
[0026] Moreover, in each of the plurality of chambers 42 divided by the above-described
plurality of partition materials 36, as illustrated in Figure 1, a hanger (not shown)
for suspending and holding a cage 44 into which the work W is to be inserted is provided.
The work W may be directly held by this hanger.
[0027] On an upper part of the cage 44, a rotation shaft 46 is provided. To this rotation
shaft 46, a rotation chain wheel (not shown) provided above the rotary hanger 20 is
connected, and this rotation chain wheel is rotated by a rotation driving motor 48,
respectively, only if it is located in any of the above-described projection material
projection areas 18A to 18D (See Figure 7).
[0028] As a result, the hanger provided in the chamber 42 located in the projection material
projection areas 18A to 18D (that is, the chamber 42 used as the projection chamber)
among the plurality of chambers 42 is rotated. Moreover, the above-described rotation
chain wheel is switched by a connection driving cylinder 50 and the like between a
state connected to the rotation driving motor 48 and a state where the connection
to the rotation driving motor 48 is released.
[0029] Moreover, as illustrated in Figure 7, on the side wall portions of the cabinet 12,
centrifugal projectors 52A to 52D as a plurality of projectors configured to apply
shot processing to the work W by projecting a projection material to the chamber 42
located in the projection material projection areas 18A to 18D among the plurality
of chambers 42 from the outside in the radial direction of the turntable 34 are provided.
[0030] Figure 5 is a diagram illustrating a configuration of the centrifugal projector 52A,
in which Figure 5(A) is a plan view, Figure 5(B) is a front view, and Figure 5(C)
is a side view. The centrifugal projector 52A includes, as illustrated in Figure 5,
an impeller 54, a driven pulley 56, a driving pulley 58, a driving belt 60, a rotating
member 62, an expansion/contraction mechanism 64, and a driving motor 66. The impeller
54 includes a plurality of blades and is configured to project a projection material
with rotation. The driven pulley 56 is supported rotatably with respect to the cabinet
12 and is rotated integrally with the impeller 54. The driving pulley 58 is rotated
by the driving motor 66, and the driving belt 60 is wound around the driving pulley
58 and the driven pulley 56.
[0031] The rotating member 62 is formed having a plate shape and rotatably supports the
driving pulley 58. Moreover, this rotating member 62 includes one end side rotatably
connected to an impeller base door. As a result, with the rotation of the rotating
member 62, a distance between the driving pulley 58 and the driven pulley 56 can be
adjusted.
[0032] Moreover, the expansion/contraction mechanism 64 connects a rotation end portion
of the rotating member 62 and the impeller base door. This expansion/contraction mechanism
64 includes a bolt and a nut, and by rotating the bolt among them, a length can be
adjusted in the axial direction. The other centrifugal projectors 52B to 52D also
have configurations similar to that of the centrifugal projector 52A (See Figure 6,
for example).
[0033] As illustrated in Figure 1, on a lower part of the cabinet 12, lower screw conveyers
68A and 68B as a first projection material conveying mechanism are provided. The lower
screw conveyers 68A and 68B are arranged in the horizontal direction and recover the
projection material falling from the chamber 42 which is used as the projection chamber
among the plurality of chambers 42 and convey it in the horizontal direction.
[0034] Figure 3 is a rear view of the shot processing device 10, Figure 4 is a plan view
of the shot processing device 10, and Figure 8 is a rear view of a circulating portion
of the shot processing device 10. To distal ends of the lower screw conveyers 68A
and 68B, as illustrated in Figure 3, lower parts of bucket elevators 70A and 70B as
a second projection material conveying mechanism are connected. The bucket elevators
70A and 70B are arranged in the vertical direction and convey the projection material
conveyed by the lower screw conveyers 68A and 68B upward.
[0035] To upper parts of the bucket elevators 70A and 70B, upper screw conveyers 74A and
74B as a third projection material conveying mechanism are connected through separators
72A and 72B. The upper screw conveyers 74A and 74B are arranged in the horizontal
direction and convey the projection material conveyed by the bucket elevators 70A
and 70B in the horizontal direction.
[0036] To the upper screw conveyers 74A and 74B, first to fourth projection material conveying
paths are connected in order from the upstream side to the downstream side. The first
projection material conveying path is, as illustrated in Figure 2, to supply the projection
material to a balance tank 76 and includes a projection material tank 78A as a first
projection material tank, a flow-rate adjuster 80A, and an inlet pipe 82A. The second
projection material conveying path is to supply the projection material to inclined
vibration sieves 84A and 84B (See Figure 3) as the vibration sieves and includes a
projection material tank 78B, a flow-rate adjuster 80B, and an inlet pipe 82B.
[0037] Moreover, the third projection material conveying path is to supply the projection
material to the centrifugal projector 52C and includes a projection material tank
78C, a flow-rate adjuster 80C, and an inlet pipe 82C. The fourth projection material
conveying path is to supply the projection material to the centrifugal projector 52D
and includes a projection material tank 78D as a second projection material tank,
a flow-rate adjuster 80D, and an inlet pipe 82D. These first to fourth projection
material conveying paths are provided in parallel.
[0038] Moreover, in the projection material tank 78D, a level sensor 86 configured to detect
an amount of the projection material stored in this projection material tank 78D is
provided.
[0039] Moreover, on a downstream end of the upper screw conveyer 74B, a projection material
tank 78E is provided, and the projection material supplied from this projection material
tank 78E flows to an overflow pipe 88 and then, returns to the cabinet 12 and flows
to the lower screw conveyer 68B which is the beginning of a circulation system again.
[0040] The separators 72A and 72B illustrated in Figure 3 applies wind selection to the
whole amount of the projection material conveyed by the bucket elevators 70A and 70B.
That is, these separators 72A and 72B separate fine powders in air by sucking the
air. In the separators 72A and 72B, ducts 90 are provided, respectively, and the air
and fine powders flow through the ducts 90 and are separated into the fine powders
and the coarse powders in a settling chamber 92.
[0041] Moreover, the finer powders are conveyed with air in the duct 90 and enter a dust
collector 94. Only the air filtered in the dust collector 94 is discharged into the
atmospheric air. The fine powders are accumulated in a fine-powder receiving box 96
provided under the dust collector 94. Moreover, the coarse powders separated in the
settling chamber 92 are conveyed to the lower screw conveyer 68B.
[0042] Moreover, when a detected value of the above-described level sensor 86 exceeds a
specified value set in advance, that is, when there is sufficient projection material
in the circulation system, the flow-rate adjusters 80A to 80D as the switching mechanisms
are controlled so that the projection material is supplied from the projection material
tank 78A to the balance tank 76.
[0043] On the other hand, when the detected value of the level sensor 86 falls under the
above-described specified value, the flow-rate adjusters 80A to 80D are controlled
so that the projection material is supplied from the projection material tank 78D
to the centrifugal projector 52D and the projection material is supplied from the
balance tank 76 to the lower screw conveyer 68B.
[0044] Among the projection material having flowed to the inclined vibration sieves 84A
and 84B, usable projection material flows to the lower screw conveyers 68A and 68B,
while unusable projection material is accumulated in the fine-powder receiving box
96 provided under the inclined vibration sieves 84A and 84B.
[0045] Moreover, in the middle of a path from the duct 90 to the dust collector 94, a sucked-air
fire-prevention damper 98 and a precoating supply duct 100 are provided. To the precoating
supply duct 100, a precoating supply device 102 is connected. By means of them, flammable
powders are precoated and made incombustible.
[0046] Moreover, in the dust collector 94, a dust collector fan 104 and a discharged-air
fire-prevention damper 106 are provided. The discharged-air fire-prevention damper
106 shuts off the flow of air together with the sucked-air fire-prevention damper
98 (in collaboration) in the case of a fire. A rotary valve 108 to the dust collector
94 serves a role of continuously discharging dusts. Reference numeral 114 denotes
a control panel.
[0047] Subsequently, an operation of the shot processing device 10 having the above-described
configuration will be described.
[0048] First, into the cage 44 in the chamber 42 located in the work carrying-in area 14
among the plurality of chambers 42, one or a plurality of works W are inserted. Then,
the revolution driving motor 24 is operated, the rotary hanger 20 is rotated around
the revolution shaft 22 by 60 degrees, and the work W is moved to the projection material
projection area 18A.
[0049] Subsequently, the connection driving cylinder 50 is operated, and the rotation chain
wheel (not shown) corresponding to the chamber 42 having been moved to the projection
material projection area 18A is connected to the rotation driving motor 48. When the
rotation driving motor 48 is driven, the rotation shaft 46 is rotated through the
rotation chain wheel.
[0050] Moreover, the flow-rate adjusters 80C to 80F are opened, and the projection material
is projected from the centrifugal projector 52A. By the means of them, the work W
arranged on the upper part of the cage 44 is ground in a concentrated manner.
[0051] Subsequently, the revolution driving motor 24 is operated, the rotary hanger 20 is
rotated around the revolution shaft 22 by 120 degrees, and the chamber 42 having been
moved to the projection material projection area 18B is used as the projection chamber.
Then, the connection driving cylinder 50 is operated, and the rotation chain wheel
(not shown) corresponding to this chamber 42 is connected to the rotation driving
motor 48. Moreover, when the rotation driving motor 48 is driven, the rotation shaft
46 is rotated through the rotation chain wheel (not shown).
[0052] Moreover, the projection material is projected from the centrifugal projector 52B.
By the means of projection, the work W arranged on the lower part of the cage 44 is
ground in a concentrated manner. Similarly, the projection material is projected from
the centrifugal projector 52C. By the means of projection, the work W arranged on
the lower part of the cage 44 is ground in a concentrated manner.
[0053] Lastly, when the projection material is projected from the centrifugal projector
52D, the work W arranged on the upper part of the cage 44 in the chamber 42 having
been moved to the projection material projection area 18D is ground in a concentrated
manner.
[0054] Then, the revolution driving motor 24 is operated, the rotary hanger 20 is rotated
around the revolution shaft 22 by 300 degrees, and the work W is conveyed to the work
carrying-out area 16 and taken out. Moreover, the revolution driving motor 24 is operated,
the rotary hanger 20 is rotated around the revolution shaft 22 by 360 degrees, and
the work W is inputted again.
[0055] By means of continuous repetition of the above-described series of steps, a large
number of works W are sequentially subjected to shot processing.
[0056] Subsequently, actions and effects of the embodiment of the present invention will
be described.
[0057] As described above in detail, according to the shot processing device 10 according
to the embodiment of the present invention, since the plurality of bucket elevators
70A and 70B configured to convey the projection material upward are provided, each
of the bucket elevators 70A and 70B can be reduced in size in the height direction.
As a result, the overall height of the entire device can be reduced.
[0058] Moreover, when the detected value of the level sensor 86 exceeds the specified value
set in advance, the projection material is supplied from the projection material tank
78A to the balance tank 76, but when the detected value of the level sensor 86 falls
under the above-described specified value, the projection material is supplied from
the projection material tank 78D to the centrifugal projector 5252D and the projection
material is supplied from the balance tank 76 to the lower screw conveyers 68A and
68B. Therefore, a good balance can be kept in the transport amount of the projection
material without shortage of the projection material.
[0059] Moreover, the separators 72A and 72B are provided between the bucket elevators 70A
and 70B and the upper screw conveyers 74A and 74B, and the whole amount of the projection
material conveyed by the bucket elevators 70A and 70B are subjected to wind selection
by the separators 72A and 72B.
[0060] Therefore, the classification performance of the projection material can be ensured
even for a work W producing many burrs and fine powders. Moreover, by means of these
separators 72A and 72B, the inclined vibration sieves 84A and 84B configured to classify
a part of the projection material conveyed by the upper screw conveyers 74A and 74B
and a structure in which the projection material is not projected but passed through
the separators 72A and 72B and the inclined vibration sieves 84A and 84B again by
storage of the projection material in the above-described balance tank 76 and supply
of the projection material from this balance tank 76, the classification performance
of the projection material can be ensured.
[0061] Moreover, by adjusting the length in the axial direction of the expansion/contraction
mechanism 64, the rotating member 62 is rotated, whereby the distance between the
driving pulley 58 and the driven pulley 56 is adjusted, and the tension of the driving
belt 60 can be adjusted. Therefore, since it is not necessary to loosen a bolt of
a mounting portion to the impeller base door of the driven pulley 56 in order to adjust
the tension of the driving belt 60, for example, workability can be made favorable.
[0062] Moreover, the bottom wall portion 40 of the partition material 36 is inclined toward
the center side of the turntable 34 as it goes from one of the pair of side wall portions
38 to the other. Therefore, even if the projection material projected by the projector
from the outside in the radial direction of the turntable 34 hits the bottom wall
portion 40, bouncing of this projection material to the projection side can be suppressed.
As a result, durability of the projector can be ensured.
[0063] In this embodiment, the shot processing device 10 is an example, and its form can
be changed in various ways. Figures 9 to 15 illustrate a shot processing device 110
according to a variation.
[0064] A basic configuration of this shot processing device 110 is similar to that of the
shot processing device 10 according to the above-described embodiment of the present
invention. Here, regarding the shot processing device 110, the same reference numerals
are used for the members having the functions similar to those of the shot processing
device 10 according to the above-described embodiment of the present invention, and
the explanation will be omitted. Reference numerals 84 and 112 indicated in Figures
9 to 15 are a vibration inclined sieve and a hanger (a hook), respectively.
[0065] The embodiment of the present invention has been described, but the present invention
is not limited to the above but naturally can be put into practice with various deformations
within a range not departing from its gist other than the above.
Reference Signs List
[0066] 10, 110···shot processing device, 12···cabinet, 14···work carrying-in area, 16···work
carrying-out area, 18A to 18D···projection material projection area, 20···rotary hanger,
22···revolution shaft, 24··· revolution driving motor, 34···turntable, 36···partition
material, 38··· side wall portion, 40···bottom wall portion, 42···chamber, 44···cage,
46 ···rotation shaft, 48···rotation driving motor, 52A to 52D···centrifugal projector,
54···impeller, 56···driven pulley, 58···driving pulley, 60··· driving belt, 62···rotating
member, 64···expansion/contraction mechanism, 66···driving motor, 68A, 68B···lower
screw conveyer (first projection material conveying mechanism), 70A, 70B···bucket
elevator (second projection material conveying mechanism), 72A, 72B··· separator,
74A, 74B···upper screw conveyer (third projection material conveying mechanism), 76···valance
tank, 78A···projection material tank (first projection material tank), 78D···projection
material tank (second projection material tank), 80A to 80D···flow-rate adjuster (switching
mechanism), 84A, 84B···inclined vibration sieve (vibration sieve), 86···level sensor,
W···work.