Workpiece Positioning Mechanism For A Punch Press

Abstract

A workpiece positioning mechanism for a punch press includes a holder assembly for a stylus and workpiece clamps carried on a transverse rail, which is carried on horizontal side rails secured to a template-support table adjacent the throat of a punch press. A pair of cables is secured to the ends of the transverse rail and is guided about pulleys disposed at the ends of the side rails whereby when a force is applied to one of the transverse rails, one of the cables acts to equalize the application of the force to the rail, thereby eliminating any tendency of the transverse rail to cock.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a workpiece positioning mechanism for a punch press for use with a template.

2. Prior Art

In U.S. Pat. No. 3,377,887 there is shown a punch press having a workpiece positioning mechanism that includes a holder assembly slidably mounted on a transverse rail, which in turn is carried by a pair of horizontal side rails. The holder assembly supports a pair of workpiece clamps and a stylus, the stylus being cooperative with various holes in a template for thereby positioning the workpiece in various positions between the punch and die means of the punch press. In such construction, as the holder assembly is moved away from the center of the transverse rail, and forces are applied to the holder assembly to shift the transverse rail along the side rails, there is a progressively greater tendency for the transverse rail to cock on the side rails. Not only is any such tendency to cock an inconvenience, but there is a tendency also for the workpiece to cock by a corresponding angle, thus producing a positioning error which becomes magnified as the size of the workpiece increases in the direction away from the transverse rail.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a pair of cables secured at the ends of the transverse rail and guided by a pulley system such that a force applied to the transverse rail at one end thereof to shift the same is equalized by being partially transferred by one of the cables to the opposite end of the transverse rail.

Accordingly, it is an object of the present invention to provide a workpiece positioning mechanism for a punch press wherein such mechanism is so constructed that the workpiece will not cock.

Another object of the present invention is to provide a workpiece positioning mechanism which will not bind when forces are applied when translational forces are applied non-centrally.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

ON THE DRAWING:

FIG. 1 is a perspective view of a punch press having a workpiece positioning mechanism provided in accordance with the principles of the present invention;

FIG. 2 is an enlarged perspective view of the workpiece positioning mechanism of FIG. 1;

FIG. 3 is a perspective diagrammatic view of the cable and pulley system forming part of the present invention; and

FIG. 4 is an enlarged cross-sectional view of a cable adjusting mechanism forming a part thereof.

AS SHOWN ON THE DRAWINGS

The principles of the present invention are particularly useful when embodied in a punch press 10 having a workpiece positioning mechanism such as shown in FIG. 1, generally indicated by the numeral 11. The illustrated punch press 10 is of the turret type, but the workpiece positioning mechanism 11 can also be utilized with single station presses. The workpiece positioning mechanism 11 includes a base 12 having a template-support table 13 illustrated as supporting an apertured template 14 which has apertures sized to snugly receive a stylus 15, thus defining the coordinates of holes or other formations to be formed by the punch press 10 in a workpiece 16.

As best seen in FIG. 2, the workpiece positioning mechanism 11 further includes a pair of horizontal side rails 16, 17 fixedly secured at their ends to the template-support table 13, the side rails 16,17 being spaced from each other and lying parallel to each other. A transverse rail 18 has a bearing assembly 19 at one end by which the rail 18 is slidably supported on the side rail 16, and has a bearing assembly 20 at the other end by which the transverse rail 18 is slidably supported on the side rail 17. In this embodiment, the transverse rail 18 has a stiffener portion 21, the side thereof nearer the punch press being hereinafter referred to as the leading face 22 of the transverse rail 18, an oppositely directed face being hereinafter referred to as the trailing face 23.

A holder assembly 24 is slidably carried on the transverse rail 18 and holds the stylus 15 at one side of the trailing face and also supports or holds workpeice clamps (not shown) at the other side of the leading face 22 for rendering the workpiece 16 comovable therewith.

A series of eight guide pulleys 25-32 are disposed at the ends of the side rails 16,17. The series or system of guide pulleys includes the pulleys 25-28, each of which is rotatable about an axis that is parallel to the transverse rail 18. The guide pulleys 29-32 are each rotatable about an axis which is below the rotational axes of the pulleys 25-28, and which is inclined to the length of the transverse rail 18. The pulleys 29,31 lie in a common vertical plane and the pulleys 30,32 lie in a second common plane which intersects the first mentioned common plane whereby each such lower pulley is directly aligned with a pulley disposed diagonally therefrom. The pulleys at each corner such as 25,29 are disposed one above the other such that their vertical tangents are substantially vertical, disregarding the depth of the pulley groove and the diameter of the cable.

The workpiece positioning mechanism 11 further includes a pair of cables 33,34. The cable 33 is secured at one end to the leading face 22 of the transverse rail 18 and extends horizontally, parallel to the side rail 17 to the pulley 26 which directs it downwardly to the pulley 30 which directs it diagonally to the pulley 32 which directs it upwardly to the pulley 28 which directs it horizontally parallel to the side rail 16 to the trailing face 23 of the transverse rail 18. Similarly, the cable 34 is secured at one end to the trailing face 23 of the transverse rail 18 near the bearing 20 and extends horizontally to the pulleys 25, 29, then diagonally to the pulleys 31,27 in intersecting relation to the cable 33, then horizontally to the leading face 22 of the transverse rail 18 adjacent to the bearing 19. The intersecting portions of the cables 33,34 lie beneath the template-support table and thus do not interfere with the template 14 or the workpiece 16. Thus the template-support table lies vertically between the upper horizontal tangent of the pulleys 25-28 and the lower horizontal tangent of the pulleys 29-32.

As best shown in FIG. 4, there is provided cable adjusting means 35 for adjusting the angle between the transverse rail 18 and the horizontal side rails 16,17. For this purpose, an end of the cable 33 is provided with a stud 36 that has a threaded portion that projects through an opening 37 in the leading face 22 in the transverse rail 18. A flanged bushing 38 surrounds the stud 36 and projects into the aperture 37, and a pair of nuts 39,40, when tightened, clamp the transverse rail 18 and the bushing 38 therebetween, thus positively holding in an adjustable manner the end of the cable 33. As explained before, the other end of the cable 33 is securely anchored at the opposite end of the transverse rail 18. At such opposite end, the cable 34 is provided with cable adjusting means the same as the means 35 just described, while its other end, as shown in FIG. 4 is likewise provided with a stud 41 which is threaded into a threaded aperture 42 in the transverse rail 18, being securely locked in place by a nut 43. The structure 41-43 is the same as that used to anchor the other end of the cable 33.

When the holder 24 is moved to the right and pulled toward the viewer, there is a tendency for the end of the transverse rail 18 having the bearing 20 to move toward the viewer while the opposite end having the bearing 19 tends to remain stationary. However, the equalizing structure provided by the cables and pulley system not only tneds to move the nearer end of the rail 18 toward the viewer, but also applies a tension to the end of the cable 33 which is nearer the bearing 20, and thus to pull that end of the cable toward the viewer. Since the opposite end of the cable 33 is fastened to the trailing edge of the transverse rail 18 near the bearing 19, there is thus also a corresponding force to pull that end of the transverse rail 18 toward the viewer, thus avoiding any tendency to cock the rail 18 and hence the workpiece and avoiding any tendency for sticking to occur at either of the bearings 19,20. The present structure enables the length of the bearings 19,20 to be held to a minimum, namely that needed for support, and not for providing prevention of cocking. When the holder 24 is moved away from the viewer the cable 34 becomes tensioned to move the opposite end away from the viewer. When the holder 24 is at the remote end of the transverse rail 18 tension is, of course, applied to the ends of the cables 33,34 which are nearer the bearing 19 to produce a similar result. The cables 33,34 are taut and their effective length is adjusted by the cable adjusting means 35, one for each cable, so that not only tautness is maintained but so that their effective lengths are adjusted to insure that the transverse rail 18 is exactly perpendicular to side rails 16,17.

Although various minor modifications may be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon, all such embodiments as reasonably and properly come within the scope of my contribution to the art.

Claims

I claim as my invention:

1. A workpiece positioning mechanism for a punch press, comprising:

a. a pair of parallel spaced-apart horizontal side rails arranged to be fixedly secured to the punch press;

b. a transverse rail slidably supported at its ends on said side rails, and having oppositely directed elongated trailing and leading faces, the leading face being closer to the punch press;

c. a holder assembly slidably supported on said transverse rail;

d. a series of guide pulleys disposed at the ends of said side rails; and

e. a pair of cables respectively secured at one end thereof to an end of said transverse rail and extending from its trailing face to one of said guide pulleys at one end of said side rail and thence to another of said guide pulleys at the opposite end of the other side rail, each of said cables being secured at its other end to the other end of said transverse rail at the leading face thereof.

2. A workpiece positioning mechanism according to claim 1 in which said guide pulleys at one end of one of said side rails comprises a first pulley rotatable about an axis parallel to said transverse rail, and a second pulley rotatable about a horizontal axis below and inclined to said transverse rail.

3. A workpiece positioning mechanism according to claim 1 including a fixed template-support table to which said side rails and guide pulleys are secured, said table overlying the intersecting portions of said cables disposed between said side rails.

4. A workpiece positioning mechanism according to claim 1 including a fixed template-support table, a first of said guide pulleys at one end of one of said side rails having an upper horizontal tangent lying above said table and a second of said guide pulleys adjacent to said first guide pulley having a lower horizontal tangent lying below said table.

5. A workpiece positioning mechanism according to claim 1 including means at an end of each of said cables for adjusting the effective length thereof whereby the angle between said transverse rail and said side rails may be adjusted.

6. A workpiece positioning mechanism according to claim 5 in which said adjusting means comprises a stud on the end of the cable projecting through an opening in said transverse rail, a flanged bushing in said opening surrounding said stud, and a pair of nuts on said stud for clamping said bushing and said transverse rail therebetween.