GB2058641A - Improvements in and relating to cropping machines - Google Patents

Abstract

The invention relates to the provision of adjustable stop means disposed above the table T of a cropping machine for sheet material W. When a sheet W having a leading edge 21 which is inclined to a side 20 of the sheet is to be stopped at a particular position on the table relative to the cutters of the cropping machine (not shown) the side 17c of a block 17 is used. Side 17b is used for a leading edge at 90 DEG to that shown and a face 17e for a square cut leading end. A side block 16 engages the side 20 of the sheet. <IMAGE>

Description

SPECIFICATION Improvements in and relating to cropping machines This invention relates to an improved cropping machine of the kind used for cutting sheet-like material, the cut being at a given angle to the direction of feed of sheet-like material to the machine. There are many manufacturing processes in which accurate angled cuts have to be made across the full width of the fed sheet-like material and this invention is concerned with an improved arrangement for controlling the length of sheet material cut on such a machine.

The invention has particular utility in the cutting of laminations for transformer cores, which laminations have to be cut with ends at accurate angles and of accurate lengths in order that the various pieces which make up the laminations of the core fit snugly together in the core.

In the specification of my U.K. Patent 1535815 I describe a cropping machine which facilitates the angled cutting of sheet-like material and this invention has particular application to a machine.

of that kind.

According to the present invention a cropping machine comprises a frame having first and second relatively movable cutting edges which cooperate to cut sheet material, fed thereto, in a cutting plane, a table on which sheet material being cut rests prior to cutting and adjustable stop means on the table to arrest the leading end of the sheet material at the required position downstream of the cutting plane to give the desired length of cut material and is characterised in that the stop means includes spaced-apart first and second faces, the first face being adapted to engage a side edge adjacent to its intersection with the leading edge of a sheet resting on the table and the second face being adapted to engage the leading edge of the said sheet.

Suitably, the first and second faces depend from a support member which is movable along the table (i.e. towards and away from the cutting edges) and across the table. Conveniently the support member is slidably mounted upon a guide bar which extends across the table from side to side and suitably is inclined at an angle (e.g. 450) to the direction of advance of sheet material over the table.

Conveniently where a support member is provided for the first and second faces, the second face is formed on a member movable in a slot in the support member, said movable member having at least one other face which is usable as the said second face when there is a different angle between the side and leading edges of a sheet being cut on the table.

Desirably the stop means also includes a transducer for sensing when the leading edge of the sheet material is close to at least one of the first and second faces forming the stop means. In this way, the transducer can be used to inhibit further advance of the sheet material towards the stop means when that material is almost in its desired position and allow the natural overrun of the drive means to move the material precisely into its final position.

One embodiment of cropping machine in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic front elevation of the cropping machine, Figure 2 is a plan on an enlarged scale of one edge of the table of the cropping machine showing the stop means, and Figure 3 is a section on the line Ill-Ill in Figure 2, The cropping machine shown in Figure 1 is described in detail in my prior U.K. Patent Specification 1535815 and broadly comprises a pair of cutting edges 3 and 6 movable into a cropping action by means of a pneumatic ram 8 inter-connecting an upper member 7 of the cropping machine with a slidably mounted portion 6a, the portion 6a sliding on pillars 5 carried by supports 4 of a main base member 1 of the machine.The member 1 and the components supported from it can be turned around the axis shown dotted in Figure 1 so that sheet material fed between the cutting edges 3 and 6 (in a direction out of the paper as shown in Figure 1) can be cut to leave a leading edge which is at some chosen angle to the side edge of the sheet material being cut. In a typical case this leading edge would either be at 900 to the side edge or at +450 or -450 from that right-angle position. The specification of my co-pending application describes an arragement for accurately setting the angle of cut.

Figures 2 and 3 show the form of stop means used to arrest the leading end of a cut sheet at the desired distance from the cutting edges 3 and 6 so that after the next cutting operation a sheet of precisely the required dimension will be produced.

Downstream of the cutting edges 3 and 6 the sheet material rests on the table T (shown dotted in Figure 1 and shown in part on an enlarged scale in Figures 2 and 3). The Table T is somewhat wider than the maximum width of strip material which can be cut on the machine and has two well-defined edges 10, the lefthand one of which can be seen in Figures 2 and 3. A carriage 11 (only one of which is shown in Figure 2) engages each edge 10 of the Table T, the two carriages being interlinked by a guide bar 12 which extends at an angle of 450 from edge to edge of the table. Each carriage can move towards and away from the cutting edges 3, 6 in the directions of the arrows A shown in Figure 2 so that the position of the guide bar 12 across the Table T is-adjustable also. Each carriage can be locked in its adjusted position by means of knurled screws 13.

Slidably mounted on the guide bar 12 is a support member 14 which can be clamped by means of screws 1 5 in any position along the guide bar 12 and, thus, by virtue of the inclined disposition of the guide bar 12 over the Table Tat a desired distance from the left-hand side edge 10.

The support member 14 includes a side block 16 depending from the underside of the support member 14 and contacting the table T and a block 17 attached to the underside of a peg 18 which is slidably contained in a groove 19 in the support member 14 (peg not shown in Figure 2).

It is one face of the block 16 and one face of the block 17 which together define the stop means to arrest the advance of the leading edge of a cut sheet being fed through the gap between the cutting edges 3 and 6.

Figure 2 shows the stop means set for arresting the advance of a sheet W having first side edge 20 and a leading edge 21 at 450 thereto. The member 14 is moved along the guide bar 12 (in the direction of the arrow B) until the face 1 6a of the side block 16 is accurately lined up with the path of movement of side edge 20 of the workpiece and the block 17 is located somewhere in the limb 1 9a of the groove 1 9 so that face 1 7a of block 1 7 bears against one side of the guide bar 12 and face 1 7c is positioned to engage the leading edge 21 of the sheet W when the latter reaches its desired position for the next cropping operation.It will be appreciated that provided the block 17 is located somewhere in the limb 1 9a it will not be critical in stopping the apex 22 of the sheet W in the desired position, this position being set by the carriages 11 along the side edges 10 of the Table T.

In an automated cropping machine the sheet material would be fed through the cutting edges by means of powered rollers on the upstream side of the cutting edges and power supply to such drive rollers can be terminated on a signal from a sensor 23 mounted on the support member 14. This sensor can be of any convenient type (e.g.

photoelectric, magnetic or capacitive) and feeds its sensing signal via a cable 24 to control the drive rollers. By turning off the drive rollers when the apex 22 is passing the sensor 23 the slight overrun of those rollers can be employed to gently bring the leading edge 21 of the sheet W into contact with face 17c of the block 1 7.

When the leading edge 21 makes an angle of 1350 with the side edge 20, the peg 18 is moved into the far end of the limb 1 9a of the slot 1 9 so that face 1 7d of block 17 abuts a surface 23 on the member 14 and the face 1 7b of the block 17 is positioned to engage the leading edge 21 and again arrest the advance of the sheet W in the correct position.

To arrest the leading end of a sheet W when this is square to the edge 20, the corner of the block 17 closest to the cutting edges 3 and 6 (i.e.

the corner between faces 1 7b and 1 7c) can be ground away (as shown dotted) to give a new face 1 7e. The slot 19 can be provided with an intermediate portion between limbs 1 9a and 1 9b to receive the peg 18 when this face 1 7e is to be used as the stop for the leading edge of a sheet W.

Figure 3 shows a sectional view through the peg 18 and the block 17 and shows a spring 25 which is used to lock the peg 18 in an adjusted position along the groove 1 9. To alter the positiori of the peg, downward pressure can be applied to a knob 26 of the peg 18 to compress the spring 25 slightly and release the peg for free movement in the groove.

Moving the peg 18 into the limb 1 9b takes the block 1 7 out of the path of the sheet W for its removal from the table Tfollowing a cutting operation.

Claims (7)

1. A cropping machine comprising a frame having first and second relatively movable cutting edges which cooperate to cut sheet material, fed thereto, in a cutting plane, a table on which sheet material being cut rests prior to cutting and adjustable stop means on the table to arrest the leading end of the sheet material at the required position downstream of the cutting plane to give the desired length of cut material, characterised in that the stop means includes spaced-apart first and second faces, the first face being adapted to engage a side adge adjacent to its intersection with the leading edge of a sheet resting on the table and the second face being adapted to engage the leading edge of the said sheet.

2. A cropping machine as claimed in claim 1, in which the first and second faces depend from a support member which is movable along and across the table.

3. A cropping machine as claimed in claim 2, in which the support member is slidably mounted upon a guide bar which extends across the table from side to side and is inclined to the direction of advance of sheet material over the table.

4. A cropping machine as claimed in claim 3, in which the guide bar is disposed at an angle of 450 to the direction of advance of sheet material over the table.

5. A cropping machine as claimed in any preceding claim, in which a support member is provided for the first and second faces, the second face is formed on a member movable in a slot in the support member, said movable member having at least one other face which is usable as the said second face when there is a different angle between the side and leading edges of a sheet being cut on the table.

6. A cropping machine as claimed in any preceding claim, in which the stop means also includes a transducer for sensing when the leading edge of the sheet material is close to at least one of the first and second faces forming the stop means, the transducer thereby being usable to inhibit further advance of the sheet material towards the stop means when that material is almost in its desired position and allow the natural overrun of the drive means to move the material precisely into its final position.

7. A cropping machine substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.