GB2242392A - Press - Google Patents

Abstract

A bench press has a ram slidable in spaced apart bearing portions 21, 22 of a headstock, and operable by a pivotable lever (13, Fig. 2) connected to the ram by link means 14, 16 operating in tension. The link means may comprise a sprocket and chain arrangement (Fig. 7) or a rack-and-pinion arrangement (Fig. 8). <IMAGE>

Description

PRESS This invention relates to a press and particularly to a hand-operated bench press suitable for light press work.

Hand-operated bench presses are frequently used to assemble components where the batch size or production rate is not sufficiently high to justify automation.

In the past manufacturers have used conventional fly presses for light press work. Such presses are relatively massive and require considerable strength and stamina from the operator to sustain a high production rate. A fly press is awkward and uncomfortable to use since the operating arm is a considerable distance from the workpiece, it is also difficult to operate when sitting.

Further disadvantages of fly presses are that they have a restricted stroke, have a fixed gear ratio, can generally only press vertically and have a maximum throat size; they are also very expensive and heavy.

As an alternative to the fly press manufacturers have sought to adapt toggle clamps for use in light press work.

Toggle clamps are quick release clamps usually employing an over centre mechanism for locking a workpiece to a support.

They are quite unsuitable for press work because the arrangement of levers and arms is not sufficiently strong and precise.

Toggle clamp mechanisms also have the disadvantages of fixed ratio and limited stroke.

The present invention provides an improved bench press which overcomes the aforementioned problems.

According to the invention there is provided a press having a frame, a headstock on the frame, a ram slidable in spaced apart bearing portions of the headstock, a shaft pivotable in the frame and having an operating handle attached to one end thereof and lever means attached to the other end thereof, link means being provided between said lever means and said ram. Arcuate movement of the operating handle thus causes the lever means to move the ram in the headstock bearings.

Preferably a return spring is provided for the operating handle; such a spring may for example be provided between the frame and the link means.

In one embodiment the lever means comprises a crank arm connected to the shaft by splines and/or a pinch bolt.

The link means preferably comprises a connecting rod freely pivoted at its ends to the lever arm and ram. In this arrangement the lever ratio of the arm changes as the operating handle is moved arcuately, and this variation may be used advantageously to achieve a desired press force/travel relationship.

Alternatively the lever means may comprise a sprocket or pulley, and the link means may include a chain or cable connection. Idler wheels may be provided. In this arrangement the force/travel relationship is constant as the operating handle is moved.

As a further alternative the lever means may comprise a pinion for engagement with a rack forming part of said link means.

Preferably the arcuate position of the lever means is adjustable with respect to the arcuate position of the handle; this arrangement ensures that the operating handle may be moved to a comfortable position for the operator. In addition the facility for handle adjustment allows the press to be placed in any desired orientation.

Further features of the invention will be apparent from the following description of a preferred embodiment shown by way of example only in the accompanying drawings in which: Fig 1 is a side elevation of a hand-operated press according to the invention.

Fig 2 is the front elevation of the press of Fig 1; Fig 3 is a plan view of the press of Fig 1; Fig 4 illustrates a stroke adjuster for the press of Fig 1; Fig 5 is an end elevation of a pivot bracket for use with the press of Fig 1; Fig 6 is a side elevation of the bracket of Fig 5; Fig 7 is an alternative operating arrangement for the press of Fig 1; and Fig 8 is another alternative operating arrangement for the press of Fig 1.

With reference te the drawings a frame 10, cast in a suitable metal, has a boss 11 extending on one side thereof.

A shaft 12 is journalled in the boss and carries an operating arm 13 on the outer end; the inner end of the shaft has a crank arm 14 attached thereto by a pinch bolt 15 as shown. The inner end of shaft 12 may be splined or otherwise adapted to hold the arm 14 in secure driving relationship.

A connecting rod 16 pivotally connects the crank arm 14 to a flange 19 of ram 17 journalled in the head of the frame; pivot pins 18 are retained by any conventional means such as circlips. The flange 19 may be connected to the ram by any suitable means.

As illustrated the ram 17 is journalled in spaced bearings partly constituted by the frame 10 and respective bearing caps 21 and 22. Other bearing arrangements for the ram are possible.

A return spring 23 acts between the connecting rod 16 and frame 10 as illustrated.

A workpiece table 24 is shown bolted to the frame 10; this is not an essential part of the invention but provides a convenient reaction member for some pressing operations.

A simple stroke adjuster is illustrated in Fig 4. An arm 25 connected to the top of the ram 17 has an aperture through which protrudes a threaded stud 26 fixed to the head of the frame. Movement of the ram causes the arm 25 to move up and down the stud as indicated by arrow 27. Nuts 28 and 29 provide travel stops thereby permitting the starting position and stroke of the ram to be simply set. Rotation of the crank arm 14 relative to the shaft 12 permits the starting position of the operating arm 13 to be adjusted to a comfortable position for the user.

An additional adjustable stop is illustrated comprising a bolt 31 threaded in the frame and lock nut 32; such a stop may operate on the crank arm 14 where it is inconvenient to provide the stop illustrated in Fig 4.

Other stops may be provided in the frame to act on the lever arrangement at any convenient position.

In use the press is operated by arcuate movement of the operating handle 13 so moving the connecting rod downward against the effect of the return spring 23. It is relatively simple and inexpensive to extend the ram to a desired length or to substitute a ram of different length.

The lever ratio of the press may be changed by substituting the crank arm 14, or alternatively the crank arm could have a plurality of holes therein adapted to receive the pivot pin of the connecting rod.

The return spring may be anchored on any convenient part of the operating linkage, and may be other than a tension spring; a tension spring is however preferred for ease of fitting and force adjustment.

The frame may be fixed through holes in the base to a bench for vertical press work but it suitable for fixing at any desired angle to enable pressing operations to be carried out in the most convenient way. The facility for adjusting the position of the handle 13 relative to the crank arm 14 ensures comfortable operation whatever the orientation of the ram.

The press frame may be pivoted in the bracket 34 illustrated in Figs 5 and 6. In use the boss 11 is machined to suit the bore of the bracket 34, the frame being held in any desired orientation by a pinch bolt 35. The shape of the frame may be adapted to allow free pivoting, for example by casting an arcuate form to the bottom rear portion of the frame as illustrated by dotted line 36 of Fig 1.

As an alternative to the connecting rod linkage, the shaft 12 and ram 17 could be connected by a chain and sprocket linkage as schematically shown in Fig 7, the lever ratio being adjusted by substituting the drive sprocket for one of an alternative size. In Fig 7 the chain is represented by the dotted line 37 and is driven by sprocket 38; an idler sprockets 39 is also shown. In the arrangement illustrated the chain is attached to the connecting rod at both ends thereof to give positive retraction of the ram on reverse movement of the operating handle. Other arrangements of chain and sprocket are possible and the shape of the frame may be changed to suit any particular advantageous arrangement.

Fig 8 illustrates another arrangement in which a pinion 41 is attached to the shaft 12, the connecting rod 42 being formed with rack teeth as shown. An idler 43 maintains the rack and pinion in engagement for the limited angular movement of the connecting rod.

The arrangements illustrated herein are schematic and may be varied to suit the particular lever ratio and stroke desired.

Claims (10)

1. A press having a frame, a headstock on the frame, a ram slidable in spaced apart bearing portions of the headstock, a shaft pivotable in the frame and having an operating handle attached to one end thereof and lever means attached to the other end thereof, link means being provided between said lever means and said ram such that arcuate movement of the operating handle causes the lever means to move the ram in said bearing portions.

2. A press according to claim 1 wherein a return spring is provided for the operating handle.

3. A press according to claim 2 wherein said spring acts between the frame and the link means.

4. A press according to any preceding claim wherein said lever means comprises an arm connected to the shaft by splines.

5. A press according to any of claims 1-3 wherein said lever means comprises an arm connected to the shaft by a pinch bolt.

6. A press according to any preceding claim wherein link means comprises a connecting rod freely pivoted at its ends to the lever arm and ram.

7. A press according to any of claims 1-3 wherein said lever means comprises a sprocket and the link means includes a chain.

8. A press according to any of claims 1-3 wherein said lever means comprises a pulley and the link means include a cable.

9. A press according to any preceding claim wherein the arcuate position of the lever means is adjustable with respect to the arcuate position of the handle.

10. A press substantially as described herein with reference to the accompanying drawings.

10. A press substantially as described herein with reference to the accompanying drawings.

Amendments to the claims have been filed as follows

1. A press having a frame, a headstock on the frame, a ram slidable in spaced apart bearing portions of the headstock, a shaft pivotable in the frame and having an operating handle attached to one end thereof and lever means attached to the other end thereof, link means being provided between said lever means and said ram such that arcuate movement of the operating handle causes the lever means to move the ram in said bearing portions, said link means being connected to said ram between said bearing portions.

2. A press according to claim 1 wherein a return spring is provided for the operating handle.

3. A press according to claim 2 wherein said spring acts between the frame and the link means.

4. A press according to any preceding claim wherein said lever means comprises an arm connected to the shaft by splines.

5. A press according to any of claims 1-3 wherein said lever means comprises an arm connected to the shaft by a pinch bolt.

6. A press according to any preceding claim wherein link means comprises a connecting rod freely pivoted at its ends to the lever arm and ram.

7. A press according to any of claims 1-3 wherein said lever means comprises a sprocket and the link means includes a chain.

8. A press according to any of claims 1-3 wherein said lever means comprises a pulley and the link means include a cable.

9. A press according to any preceding claim wherein the arcuate position of the lever means is adjustable with respect to the arcuate position of the handle.