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(11) | EP 1 057 600 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Short piece feeder |
| (57) A short piece feeder (1) for use with a multi-axis wood moulding machine having a
rotary cutting head (20) for machining a workpiece (30). The short piece feeder comprises
a reciprocating member (2,3) having a block (4) mounted on one end. A dog (6) is pivotably
mounted on the block (4) and engages with a trailing end (32) of the workpiece (30)
when the trailing end (32) moves past and clears the dog (6). Detection of the trailing
end (32) of the workpiece (30) causes the activation of the reciprocating member (2,3)
to draw the workpiece (30) across the rotating cutting head (20) of the multi-axis
wood moulding machine, until the workpiece (30) is engaged by the feed roll (22b)
downstream of the rotary cutting head (20). |
TECHNICAL FIELD
[0001] The invention relates to a short piece feeder for use with a multi-axis wood moulding machine.
BACKGROUND ART
[0002] Multi-axis wood moulding (MAWM) machines are well known for machining a wooden workpiece into a variety of shapes. The MAWM machines commonly have four rotating cutting heads, one for each of the surfaces to be worked, but may have more if particularly smooth surfaces or complex shaping is required. Vertical axis cutting heads, or "side heads" are used to machine the side surfaces of the workpiece and horizontal axis cutting heads, known as a "top head" and a "bottom head", are used to machine the upper and lower surfaces. The MAWM machine may also have a "universal head" which can rotate through 90 degrees and can be used as either a top, bottom or side head. The heads each include a number of rotary cutting blocks which can be planing blocks for producing a flat, smooth surface, or alternatively moulding blocks for producing more intricate surfaces.
[0003] Each head typically is associated with at least one rotating feed roll on either side. The feed rolls are designed to engage the workpiece and to move it across the cutting line of the head. The feed rolls are biased against the workpiece which also ensures that the workpiece is held securely against a bed or against a side fence for a smooth finish.
[0004] The MAWM machine described above works well for workpieces which are longer than the distance between the two feed rolls disposed one on each side of the head. However, problems occur when the workpieces are shorter than this distance. With long workpieces, the workpiece is engaged by the second feed roll downstream of the head before the first feed roll loses engagement. As a result, there is at least one feed roll engaging with the workpiece at all times during cutting. This is not the case with short workpieces where only part of the workpiece is moved across the cutting line of the head before the first feed roll loses engagement with the workpiece. The second feed roll is unable to engage the workpiece and the workpiece simply stops. The workpiece remains stationary until it is moved forward by another workpiece which is following on behind. As well as being stationary, the workpiece is also free to move. This can lead to small notches in the surface of the workpiece and inaccurate machining, both of which are highly undesirable.
[0005] Typically, the problem is lessened by placing the two feed rolls as close to the heads as possible, thereby reducing the distance between the feed rolls so that shorter workpieces may be accurately machined. However, this is not an ideal solution since sufficiently short workpieces can still be left stationary.
SUMMARY OF INVENTION
[0006] The invention provides a short piece feeder for use with a multi-axis wood moulding machine having a rotary cutting head for machining a workpiece, the short piece feeder including:
a reciprocating member; and
a dog pivotably mounted on one end of the reciprocating member, such that when the reciprocating member is operated, the dog engages with a trailing end of the workpiece and draws the workpiece across the rotary cutting head.
[0007] A sensor for detecting the trailing end of the workpiece is typically used to start the operation of the reciprocating member and is preferably a microswitch or a proximity switch.
[0008] Preferably, the dog is biased to a first position by a light spring when not in contact with a side of the workpiece, and pivoted to a second position when in contact with a side of the workpiece.
[0009] Alternatively, the dog may be pivoted to the first position in response to the sensor detecting the trailing end of the workpiece.
[0010] The action of pivoting of the dog from the second position to the first position may be alternatively used to start the operation of the reciprocating ram.
[0011] The reciprocating member is usually a ram having a piston rod and a cylinder and is preferably hydraulically or alternatively pneumatically driven.
DRAWINGS
[0012]
Figure 1 shows a top view of a short piece feeder according to the present invention;
Figure 2 shows a rear view of the short piece feeder of Figure 1;
Figure 3 shows a multi-axis wood moulding machine top head incorporating a short piece feeder according to the present invention at an initial instant in time;
Figure 4 shows the multi-axis wood moulding machine top head of Figure 3 at a later instant in time.
[0013] Referring first to Figures 1 and 2, a short piece feeder 1 includes a hydraulic ram which comprises a piston rod 2 and associated cylinder 3. A block 4 is mounted on the free end of the piston rod 2. A dog 6 is pivotably mounted on the block 4 about an axis 8. A first end of the dog 6 also is attached to the block 4 by a light spring 10 which biases the dog 6 to a first position 6a as shown in Figure 1. A wooden workpiece (not shown) which is to be machined is positioned flush against a side fence 12, and on contact with the dog 6 can pivot the dog 6 inward to a second position 6b such that an outer end 14 of the dog 6 is flush with the side fence 12.
[0014] The operation of the short piece feeder 1 is now explained with reference to Figures 3 and 4. In addition to the short piece feeder 1, Figures 3 and 4 also show a top head 20 and associated feed rolls 22a, 22b of the type commonly found on MAWM machines. The feed rolls 22a, 22b are rotatably driven by driving means (not shown) and are mounted on biased supports 24 to allow them to move up and down to accommodate a variety of workpieces.
[0015] The short piece feeder 1 is initially set at the position shown in Figure 3 with the ram at full extent, and is separated from the workpiece 30 by a side fence 12. The side fence 12 includes a slot 28 along its length to allow the dog 6 to protrude through the side fence 12 when in the first position 6a. The workpiece 30 sits on a bed 26 and against the other side of the side fence 12 and is driven by the first feed roll 22a towards the top head 20 in the direction shown by the arrow AA. As the workpiece 30 moves toward the top head 20 it is pushed up against the dog 6 which is in the first position 6a and pivots the dog 6 to the second position 6b. The side of the workpiece 30 then keeps the dog 6 in the second position as the workpiece 30 is driven past the block 4 by the first feed roll 22a.
[0016] The block 4 is initially positioned such that the trailing end 32 (Figure 4) of the workpiece passes the front end of the dog 6 as the first feed roll 22a loses engagement with the workpiece 30. The dog 6 is then no longer held in the second position 6b by the side of the workpiece 30 and is pivoted outwards into the first position 6a by the spring 10 (Figure 1). A microswitch (not shown) mounted on the first feed roll 22a detects the trailing end 32 of the workpiece and triggers the short piece feeder mechanism. As the ram begins its reverse stroke as shown by arrow BB, the dog 6 in its first position 6a engages with the trailing end 32 of the workpiece 30 and proceeds to draw the workpiece 30 across the top head 20.
[0017] The ram continues its reverse stroke until the whole of the workpiece 30 has been machined by the top head 20. The block 4 may be moved all the way across the cutting line (CL) (Figure 4), or in an alternative embodiment the block 4 may be moved just sufficiently far to ensure that the workpiece 30 is engaged by the second feed roll 22b downstream of the top head 20. Once the whole of the workpiece 30 has been machined and the ram has completed its reverse stroke, the ram then changes direction and the block 4 is returned to its original position as shown in Figure 3.
[0018] On the return stroke, the dog 6 remains in the first position 6a unless it meets another workpiece which then pivots the dog 6 inwards to the second position 6b. Otherwise, the dog 6 remains in the first position 6a until the ram completes its return stroke and remains there until the next workpiece arrives.
1. A short piece feeder for use with a multi-axis wood moulding machine having a rotary
cutting head for machining a workpiece, the short piece feeder including:
a reciprocating member; and
a dog pivotably mounted on one end of the reciprocating member, such that when the reciprocating member is operated, the dog engages with a trailing end of the workpiece and draws the workpiece across the rotary cutting head.
2. A short piece feeder according to claim 1, further including a sensor, wherein the
sensor detects the trailing end of the workpiece and starts the operation of the reciprocating
member.
3. A short piece feeder according to claim 2, wherein the sensor is a microswitch.
4. A short piece feeder according to claim 2, wherein the sensor is a proximity switch
5. A short piece feeder according to any preceding claim, wherein the dog is biased to
a first position when not in contact with a side of the workpiece, and pivoted to
a second position when in contact with a side of the workpiece.
6. A short piece feeder according to claim 5, wherein the dog is biased to the first
position with a light spring.
7. A short piece feeder according to any preceding claim, wherein the reciprocating member
is a ram including a piston rod and a cylinder.
8. A short piece feeder according to claim 7, wherein the ram is hydraulically driven.
9. A short piece feeder according to claims 7, wherein the ram is pneumatically driven.