GB2200070A - Shearing machine - Google Patents

Abstract

The invention provides a shearing machine for sheet materials incorporating a blade 4 relatively movable with respect to lateral die elements 8,9 so as to shear a portion of the material corresponding substantially to the width of the blade, the blade also coacting with a front die element (10, Fig. 3) in which at least one lateral die element is mounted on a carrier 13 which is movable at least in part laterally with respect to the general support structure 1 of the machine. Manually-operable means such as a turnbuckle device 18-20 ads between the carrier and the support structure for adjustment of the carrier and of the die element carried thereby, laterally with respect to the blade, to vary the cutting clearance to suit the material being cut. The carriers may be initially outwardly splayed by screw and nut devices 16, 17. The front die is held down on blocks 12 by springs within a block 22 and is positioned by dowels (23, Fig. 3). Carriers (25 Figs. 4 & 5), more rigid than carriers 8, 9, are adjustable at both ends by an arrangement of nuts and parallel levers (28-36). <IMAGE>

Description

Shearing Machine This invention relates to a shearing machine for sheet materials, and in particular for sheet metal. The machine is of the kind having a blade which is relatively movable with respect to two lateral die elements, so as to shear a portion of the material corresponding substantially to the width of the blade. Where the blade also coacts with a front end die element in order to slot the material, the slot being accommodated by a reduced part of the body of the#machine, so as to enable an indefinite length of material to be fed to the machine, such a machine is commonly referred to as a guillotine notcher.

It is well known in the art that the very small clearance provided between the respective side face of the blade and the die element at that side must be varied in accordance with the thickness of the sheet material to be sheared. With a front end die element this factor is not important, because there is no rear end die element provided.

Hitherto, it has been usual to provide for adjustment of the lateral die elements by, for example, loosening holding means for one or both of the die elements shifting them to a new position as required by the thickness of a new material to be sheared, and then tightening them again. In practice, it has been found that, within small limits, it is sufficient if only one of the die elements is so adjusted, and the blade then allowed to find its own slightly adjusted position centrally between the two lateral die elements.

There are two drawbacks in such a system of adjustment. A first is that, whilst the self-centering ability of the blade may be adequate for the cutting of relatively thin materials, of varied thickness, it is less successful or even inoperative on thicker material because the amount of lateral flexibility in the mounting of the blade could be unacceptable. A second and important drawback is the tedium of the method of changing the lateral clearance. This can easily be a suffiently serious impediment to comfortable working as to preclude an operator from adjusting the clearance when it should be done, or again, it could completely discourage use of the machine to its full potential.

It is #accordingly the object of the present invention to provide an improvement which enables substantially instantaneous lateral adjustment of the lateral die elements with respect to the blade, which need not possess any capability at all of lateral adjustment.

According to the present invention, at least one lateral die element, and preferably both die elements, is mounted on a carrier which is movable at least in part laterally with respect to the general support structure of the machine, and manually-operable means are provided to act between the carrier and the support structure for adjustment of the carrier, and thus also of the die element, laterally with respect to the blade.

In a preferred arrangement, the carrier is caused to adopt initially a rest position in which the respective die element is too widely spaced laterally from the blade, and the adjustment means are then operable to shift the carrier, against resilient loading, back towards the blade until the correct clearance is achieved. Advantageously, the resilient loading is provided by the bending resilience of the carrier itself.

Where two such carriers are provided, one for each lateral die element, the two carriers may initially adopt a slightly splayed position, and then both be forced inwardly to the desired position. However, for ease of manufacture, the machine is constructed so that, under non-constrained conditions, the two carriers are initially parallel, but can then be strained outwardly to a splayed condition, whereafter the adjustment means can be operated to bring the die elements into correct position. By way of example, the straining outwardly of the carriers, to a splayed condition, may be obtained providing threaded straining means on each carrier abutting a common fixed portion of the machine structure, e.g. a centre plate.

The adjustment means may comprise a respective threaded means for each carrier coacting with a fixed portion of the machine structure, e.g. a common centre plate, and the threaded means may be, for example, a respective turnbuckle on each carrier engaged into a threading of the centre plate or nut thereon.

An advantage of the just mentioned embodiment of the invention is that the carriers, when outwardly splayed to, say, a maximum clearance of the die elements likely to be required, the die elements do not present a negative rake- to the cutting action. It is possible to grind the die elements with sufficient rake, but experience has shown that grinding the die elements at right angles means that they can be made reversible, that is turned over as well as side to side reversibility, and thus double the time required between re-grinds. If the spacing of the carriers is correctly adjusted, the amount which the two upper surfaces of the die elements deviate from a true plane, at certain positions of splay, is not enough to cause damage to the material being cut.Advantageously, the carriers are made relatively elongate, so as to lessen any such deviation, and incidentally to provide sufficient flexibility of a fairly stiff member. t It is found in practice that mild steel can be used for carriers made in the form of an elongate plate.

Preferably, the carriers are in the form of plates which are secured rigidly in parallel position to the structure of the machine at one end, and are sprung to splayed condition by adjustment means located intermediately along their length, and relatively near to the point of fixture to the structure. Adjustment of splay, and then subsequently adjustment of inward movement to final position, are each independently obtainable for each carrier plate, This incidentally permits relatively broad-limits to be used on the basic structure.

According to a further aspect of the invention, there is provided an improvement relating to a front-end die element. Such a front-end die element cannot readily be rigidly mounted on the general structure of the machine and still permit sideways movement of the carriers, and in particular it must not lift, or move away from, the blade.

In accordance with this improvement, the front-end dieelement is secured against lifting movement and against movement towards and away from the blade, but is left free to move laterally with respect to both of the lateral die elements, so far as~ concerns small lateral movements within limits.

In a convenient arrangement, the #front-end die element is held in position by screws which pass through that die element, then with clearance through the respective carrier, and then into a common block disposed below the adjacent portion of the carrier. The adjacent portion of the carrier, and the block, are both counterbored in opposed manner to provide a housing for a compression spring which acts to thrust the block away from the adjacent portion of the carrier, and thus to draw the front-end die element firmly, but resiliently, into seating engagement onto the carrier. The holes in the adjacent portions of the carriers, through which said screws are passed are made with sufficient clearance, or one at least may be slotted. The screws are tightened until the block abuts the undersurface of the carriers, to prevent lift of the front-end die elements. Dowels may be provided on the carriers to locate the front-end die element against movement away from the blade.

In order that the nature of the invention may be readily ascertained, two embodiments of guillotine notcher in accordance therewith are hereinafter particularly described with reference to the accompanying drawings.

In the drawings: Figure 1 is a partial front elevation of one embodiment of the invention; Figure 2 is a partial side elevation of the embodiment of Figure 1; Figure 3 is a partial plan view of the embodiment of Figure 1, viewed at "A" in Figures 1 and 2.

Figure 4 is a partial front elevation of a second embodiment of the invention; and Figure 5 is a partial side elevation of the embodiment of Figure 4.

The Figures of the drawings show only those portions of the machines which are relevant to the invention, the remainder being conventional or well within the ordinary skill of a man skilled in the art of constructing metal shearing machines.

Referring to Figures 1 and 2, the machine has a rigid vertical structural plate 1 which is welded to a pair of feet 2, only one of which is visible. The central plate 1 carries, at a point not visible in these drawings, a horizontal pivot for a pair of parallel arms 3 to the front end of which a cutter blade 4 is secured by metal screws 5. A pair of substantially upright link arms 6 are coupled at their lower end to the arms 3 and to the blade 4 by a transverse bolt 7. The upper end of the arms 6, not visible, is connected by a transverse bolt to a simple lever pivoted on the central plate 1. The action is well known, in that raising and lowering the simple lever, i.e. the usual operating handle for the machine, raises and lowers the blade 4.

To provide a shearing action, the cutting edge 4a of the blade 4 has to co-operate at each side with a respective die element, and also at its front end with a die element. In this example, the lateral die elements, best seen in Figures 1 and 3, are denoted by reference numerals 8,9 and the front element is 10. Each of the lateral die elements is secured rigidly, by screws 11 on a respective block 12 welded at the upper end of a respective carrier plate 13. Each plate 13 is rigidly secured, at its lower end, e.g. welded, to a respective block 14, and the plates 13 and blocks 14 are secured rigidly to the central plate 1 by means of bolts 15. In their non-constrained condition, the plates 13, 13 are parallel.To cause the plates 13, 13 to assume a slightly outwardly splayed condition, each plate 13 is provided with a screw 16 threaded through it and having the head of the screw abutting the central plate 1. A lock nut 17 is provided on each screw. By suitable adjustment of the screw 16 with a spanner, the plates 13, 13 can be caused to assume a splayed condition in which their respective lateral die elements 8, 9 are spaced to a greater extent than is proper for them to coact with the blade 4.

To enable the die elements 8, 9 to be precisely adjusted inwardly towards the blade 4, according to the thickness of the material which is to be cut, each plate 13 has a manually-operable turnbuckle 18 which is passed with clearance through a collar 19 and is threaded into a nut 20 welded on the central plate 1. By tightening the respective turnbuckles 18, 18 which have a domed end face on the collars 19 to reduce friction during movement of the plates 13, 13, the latter and thus also the face of the blade 4.

Referring now to Figure 3, there is shown a detail of the front-end die element 10. This is held, by screws 21, on the blocks 12 of the two plates 13, 13, but can slide laterally within small limits with respect to said blocks. The screws 21, 21 holding the front-end die element 10 are each engaged through clearance holes in the blocks 12, 12 and are then threaded into a common block 22. The blocks 12, 12 and the block 22 are each counterbored to form a housing to receive a small compression spring which thrusts the block 22 downwardly and thus draws the front-end die element 10 firmly onto the upper face of the two blocks 12, 12. Dowels 23 serve to locate the die element 10 against movement away from the blade.

The embodiment of the invention illustrated in Figures 4 and 5 is generally similar to that of Figures 1 to 3 and like parts have given the same numbers in Figures 4 and 5 as they have in Figures 1 to 3.

A number of significant changes are incorporated in this second embodiment, however, as follows.

Firstly, the carriers 25,26, as can best be seen in Figure 4, are wider than those of the arrangement of Figures 1 to 3, and it has been found that they do not need to be initially splayed outwards. This is because, with this embodiment, they are stiffer than with the first embodiment and with little more than sufficient clearance for any material suitable for a machine of the kind described there is adequate spring it the carriers themselves for them to be adjusted inwards and to return as required. For this reason, the threaded straining means illustrated by the arrangement 16 and 17 of the first embodiment is not needed and has been omitted.

Secondly, it has been found that, in certain operational circumstances, for example, where the die is of considerable length, the single turnbuckle arrangement of the first embodiment for each plate did not fully ensure the maintenance of perfect parallelism of the two lateral die elements in the manner essential for the satisfactory operation of a machine of this type. The secnd embodiment, therefore, has an opening and closing arrangement for the die elements which is positive with respect to both ends of the die elements.

Referring to Figures 4 and 5, it will be seen that, in essence, the provision is for each die element 27 to be held at both ends instead of in the centre only. In general terms, the implication of doing this is that the two points of control on each carrier need to be linked to ensure equal movement at both ends, whilst each, in practice, needs to be provided with means for individual adjustment at initial setting up to enable manufacture with reasonable tolerance to occur.

In detail, the arrangement comprises four special nuts three of which 28, 29, 30 being seen operated by four linked levers three of which 31, 32, 33 being seen clamped around turning portions of the nuts, thereby enabling them to be set in any position on the nuts and secured thereto by four screws three of which 34, 35, 36, being seen. The four levers connected by two limbs one of which, 38, being seen. At the inner end 37 of the die, the nuts engage a threaded stud 39, which is anchored securely in the body of the machine and thereby ensures that the resilience of the carriers necessary for their adjustment does not permit them to move as a single unit when in operation.

The corresponding threaded element 40 at the other end of the die is free to float, thereby preventing any danger of introducing a position where alignment of the die with the body of the machine is being held at more than one point.

In practice, right-hand threads are used on the right-hand ends of the studs 39, 40 and left-hand threads on the left-hand ends. Although, as an alternative, all threads could be right-handed, thereby saving on production costs of the machine, the use of left and right-hand threads leads to simpler and more efficient acutation, particularly from the operator's point of view.

Should additional outward thrust be desired in for the carriers to enhance their natural resilience, wave spring washers or disc springs may be provided on the studs 39, 40.

As can be seen the best in Figure 4, the control levers are normally set approximately opposed to one another for all clearance values by virtue of the left and right-hand threading arrangement, and can be moved together to open and close respectively the die elements.

The pitch of the threads of the studs 39,40 has been chosen to provide a satisfactory correlation between the arc through which the levers may comfortably be turned by an operator and the amount of die movement required with the kind of machine illustrated. This latter is normally no more than 10% of the thickness of the material being cut, 5% being the usual commercial average. Stops on a convenient part of the machine are fitted to prevent any operator closing the die to a point where the blade cannot enter the die without fouling its edges.

Thirdly, it is to be observed that the die carriers have been amended so as to incorporate cut-away portions 41 beneath the dies and their mountings. The purpose of this arrangement is to provide a method of securing the dies whereby they can be adjusted independently of the carriers to take up grinding losses. In addition, the arrangement provides means whereby any small misalignment between the line of the dies and the body of the machine can be corrected. Again, the arrangement provides an additional escape route for the scrap removed by the blade from the workpiece.

Fourthly, with the second embodiment, a simpler mounting of the block of the die elements is provided in that there is no requirement or need to counterbore the carriers in addition to the blocks. This is because, with the second embodiment, there is room for the block to be made thick enough to accept the full length of the urging spring of the kind illustrated in Figure 1, by itself. This particular feature is of importance in relation to the manufacturing costs of the machine.

It is, of course, to be pointed out that, within the scope of the invention, embodiments differing from those illustrated can be successfully provided. Thus, it is possible for sideways adjustment of the lateral die elements to be provided for in different ways to those illustrated hereinabove. For example, the technique used for making minor adjustments described hereinabove with regard to the second embodiment could be elaborated to such an extent that it could take the place of the play mountings of the embodiments of the invention illustrated.

Such an arrangement would, of course, include means for maintaining parallel movement of the die pieces and blocks.

Claims (8)

1 A shearing machine for sheet materials incorporating a blade relatively movable with respect to lateral die elements so as to shear a portion of the material corresponding substantially to the width of the blade, the blade also coacting with a front-end die element in which at least one lateral die element is mounted on a carrier which is movable at least in part laterally with respect to the general support structure of the machine; and manually operable means provided to act between the carrier and the support structure for adjustment of the carrier and of the die element carried thereby, laterally with respect to the blade.

2 A shearing machine as claimed in claim 1 in which both lateral die elements are mounted on carriers for movement at least partially laterally with respect to the general support structure of the machine, manually operable means being provided to act between the carriers and the support structures for adjustment of the carriers and the die elements supported thereon, laterally with respect to the blade.

3 A shearing machine as claimed in any one of claims 1 and 2 wherein the carrier is caused to adopt initially a rest position in which the die element carried thereby is too widely spaced laterally from the blade and the adjustment means are then operable to shift the carrier, against the resilient loading, laterally towards the blade until correct clearance is achieved.

4 A shea#ring machine as claimed in any one of the preceding claims in which the carrier element in which the or each carrying element is. laterally outwardly resiliently urged, whereby the resilient loading thereon is provided.

5 A shearing machine as claimed in claim 4 wherein spring means are provided between the two carriers to provide or add to the outward urging thereof.

6 A shearing machine as claimed in any one of the preceding claims in which the carriers are linked to the frame of the machine passing therebetween beyond each die element, and by means of interlinked levers mounted on nuts rotating on studs secured to the frame, movement of the carriers to their correct operating position against the outward urging of the carriers is achieved.

7 A shearing machine as claimed in any one of the preceding claims in which the front-end die element is secured against lifting movement and against movement towards and away from the blade, and is free and unrestrained with respect to lateral movement relative thereto of the die elements within small movement limits.

8 A shearing machine substantially as shown and as hereinbefore described with reference to Figures 1, 2 and 3, or 4 and 5 of the accompanying drawings.