GB2046655A

GB2046655A - Workpiece Holding Device

Info

Publication number: GB2046655A
Application number: GB8011574A
Authority: GB
Original assignee: Haddon J A
Current assignee: Haddon J A
Priority date: 1979-04-06
Filing date: 1980-04-08
Publication date: 1980-11-19
Also published as: GB2046655B

Abstract

A pair of arms (37), (38) are pivotally mounted about a shaft (32) on a support 30. Flanges on one arm (37) may be rigidly held against flanges (33) of the support (30) by tightening a wing nut (34) on the shaft (32) which will cause the flanges on the one arm (37) to be held against a sleeve (39) carried by the shaft (32). The other arm (38) will still be free to rotate about the sleeve (39). The two arms are biased by a spring mounted about a shaft (44) to cause gripping flanges (41) at their ends to be pressed together, between which can be held a workpiece. A flexible arm (46) carrying a gripping device (47) or some other aid can be provided to hold parts which will be used in association with the workpiece. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to Workpiece Holding Devices This invention relates to workpiece holding devices and particularly, but not exclusively, to a device suitable for holding an electrical printed circuit board while components are being mounted on the board.

When mounting electrical components on a printed circuit board it is often necessary to work alternately on the two sides of the board, when components located on one side of the board have parts which pass through holes in the board and are secured on the opposite side thereof. In practice this means that a board being worked on must be repeatedly turned over as the work progresses. Since it may be undesirable to lay the board down on a flat surface, for fear of damaging components mounted on it, the board is usually supported in the hand while operations, such as soldering operations, are taking place. Not only is this inconvenient, but the necessity of supporting the board by hand detracts from the efficiency with which the operator can carry out the requirec operations on the board.Thus, in addition to supporting the board, the user may have to manipulate the component to be mounted on the board, a soldering iron, a solder dispenser and, in some cases, some form of heat shunting device.

This may lead to unsatisfactory results, such as imperfectly soldered joints.

The invention sets out to provide a workpiece holding device which is particularly suitable for supporting a board-like workpiece, such as a printed circuit board, during operations of the kind referred to above.

Accordingly this invention provides a workpiece holding device comprising a support, a first arm structure mounted on the support for pivotal movement relative thereto, retaining means for retaining the first arm structure in a required angular position with respect to the support, and a second arm structure mounted for pivotal movement with respect to the first arm structure against resilient biasing means which biases gripping flanges on the two arm structures towards one another.

Thus, in operation, a printed circuit board may be located between the gripping flanges so as to be supported by the device, leaving both of the operator's hands free to work on the board. The arm, structures and board may then be swung readily and quickly about the pivotal mounting on the support from a position where access is given to one side of the board to another position where access is given to the other side of the board.

Preferably the means for retaining the first arm structure in a required angular position is provided by frictional engagement between said first arm structure and the support. Alternatively or additionally, the retaining means may comprise releaseable clamping means between said first arm structure and the support. The releaseable clamping means may be used to adjust the frictional engagement or may be used positively to clamp the arm structure more firmly in a particular position when required.

In the preferred embodiment both arm structures are mounted about the same pivot but the second arm structure is freely movable, against the bias of the biasing means, relative to the support and first arm structure. Thus the two arm structures could be disposed about a rod carried by the support, the retaining means comprising a nut which may be tightened on the rod to cause the first arm structure only to be retained in a required angular position with respect to the support. Ideally, in this arrangement, the second arm structure is pivotally disposed about a sleeve surrounding the rod, the sleeve ends comprising abutments against which the first arm structure and support will be gripped as the nut is tightened. A shake resistant washer is advantageously provided in association with the nut, so that the nut will not tend to loosen inadvertently.

As an alternative construction the second arm structure may be pivotally supported directly by the first arm structure, in which case it is desirable for the pivot axes of the two arm structures to lie parallel to one another.

The biasing means ideally acts between the portions of the two arm structures lying on the opposite side of the pivot axis between the two arm structures to that occupied by the gripping flanges. Preferably, the biasing means comprises a compression spring held between the said portions of the two arm structures. It is also advantageous to include an adjustable stop for limiting the movement of the gripping flanges towards one another. This adjustable stop can be provided by a nut screwed onto a bolt passing through the said portions of the two arm structures and about which is mounted the compression spring.

It is preferred that the two arm structures should be cranked away from the gripping flanges to provide a free space between the arm structures beyond the gripping flanges to receive possible projecting parts of the workpiece being held by the device.

The device may advantageously include one or more elongated adjustable arms, each secured at one end to the support or one of the arm structures, and carrying a tool or tool holder, such as a crocodile clip or other adjustable gripping member, at its free end. Each arm is ideally formed by stiff yet flexible material which will retain the attitude into which it is bent.

The invention may be performed in various ways and two preferred embodiments thereof will now be described with reference to the accompanying drawing, in which: Figure 1 illustrates one preferred form of workpiece holding device according to the invention; Figure 2 is a view of an alternative and preferred form of workpiece holding device of the invention; and Figure 3 is a vertical cross-section of the device as shown in Figure 2.

The device shown in Figure 1 has a support 10 in the form of a U-shaped bracket 1 1 mounted on legs 12 by which it may be secured to a workbench. As an alternative to providing mounting legs 12 the flanges 13 of the bracket 1 1 could be made longer so that the base of the bracket itself could be secured to the workbench.

The flanges 13 provide pivotal mounting points for an arm structure 14 whose flanges 1 5 are held against the flanges 13 by respective bolts 16 and wing nuts 17. Thus the arm structure 14 may be pivoted about the bolts 16 to a desired attitude relative to the support 10 and held there by tightening the wing nuts 17.

A second arm structure 18 is mounted adjacent the first arm structure 14 by means of cooperating lugs 19 held together by pivot pins 20. Beyond this pivot each arm structure extends as a cranked portion 21 terminating in a gripping flange 22 within which may be held a workpiece which is to be operated on. The flanges 22 are biased into a closed position by a compression spring 23 acting on the portions 24 of the arm structures 14 and 18 to the other side of the pivot points 20. The spring 23 is positioned about a bolt 25 which passes through the two portions 24 and is secured by a wing nut 26. Tightening of the wing nut 26 can create a minimum gap between the flanges 22 if desired.

In use the wing nut 26 is set in the required position and then the gap between the flanges 22 is increased by pressing together the portions 24 so that a workpiece can be positioned between the flanges 22 and can be gripped there when the portions 24 are released. If it is desired to turn the workpiece over or place it in some other attitude the wing nuts 17 can be slackened so that the arm structure 14 may be pivoted about the bolt 16 and then secured in the desired new position by tightening up the wing nuts 17. The shape of the cranked portions 21 and the areas cut away in the same region provides space for parts of the workpiece which may project and also provides access to areas on the workpiece other than those positioned beyond the flanges 22, if required.

The preferred form of workpiece holding device shown in Figures 2 and 3 has a support 30 which may be attached to a workbench by means of screws passing through holes 31 on the base of the support. A bolt 32 passes through the two flanges 33 on the support 30 and is held there by a wing nut 34. In between the flanges 33 are positioned lugs 35, 36 of two arm structures 37, 38, the lugs 35 being mounted directly onto the bolt 32 whilst the lugs 36 are mounted about a sleeve 39 which is carried by the bolt 32. When the wing nut 34 is tightened the lugs 35 will be gripped between the flanges 33 and the ends of the sleeve 39 whilst the lugs will still be free to rotate about the sleeve 39. A shake resistant washer 40 is provided to minimise the possibility of inadvertent loosening of the arm structure 37 with respect to the support 30 when the wing nut 34 has been tightened.

To one side of the pivot formed by the bolt 32 the arm structures 37 and 38 converge to form gripping flanges 41 which will grip a workpiece, To the other side of the pivot formed by the bolt 32 portions 42 of the arm structures 37, 38 are biased apart by a compression spring 43 mounted about a bolt 44 which is engaged by a wing nut 45. Again tightening of the wing nut 45 can create a desired minimum gap between the flanges 41.

In use the wing nut 34 is loosened so that the attitude of the arm structure 37 can be chosen whereupon the wing nut 34 is tightened to hold the arm structure 37 in this attitude with respect to the support 30. The portions 42 may then be pressed together against the bias of the spring 43 to create a gap between the flanges 41 for receipt of a workpiece, such as a printed circuit board whereupon the portions 42 will be released. If it is desired to alter the attitude of the workpiece the wing nut 34 is loosened so that the combined arm structures 37 and 38 may be rotated about a pivot formed by the bolt 32 to a new attitude whereupon the wing nut 34 will be tightened again.

A further useful feature provided by the device shown in Figures 2 and 3 is the provision of one or more flexible arms 46 which are secured at one end to the portion 42 of the arm structure 38 and at the other end carrying a crocodile clip 47 or some other form of gripping device. Alternatively each flexible arm 46 could be attached to flanges on the support 30. If they are mounted in this way then they will not move as the attitude of the arm structures 37, 38 is altered. The crocodile clip 47 can be used to hold components or tools adjacent the workpiece thus freeing the operator's hands for other purposes. The arms 46 may comprise a number of links pivotally connected together, or may comprise a single arm of stiff but flexible material of any known kind which will remain in the shape to which it is bent. Alternatively, for example, the arm 46 could have a magnifying glass, an illumination device or some other form of aid mounted on its end.

It will be appreciated that the device shown in Figures 2 and 3 could be modified to extend the parts leading to the gripping flanges 41 and to form an open space in those portions much assign the manner of the device of Figure 1.

It will be appreciated that the shake resistant washers 40 also provide a gap between the lugs 35 of the arm structure 37 and the support flanges 33 so that there will be no frictional resistance therebetween when the attitude of the arm 37 is altered.

Claims

1. A workpiece holding device comprising a support, a first arm structure mounted on the support for pivotal movement relative thereto, retaining means for retaining the first arm structure in a required angular position with respect to the support, a second arm structure mounted for pivotal movement with respect to the first arm structure against resilient biasing means which biases gripping flanges on the two arm structures towards one another.

2. A device according to claim 1, wherein the retaining means is provided by frictional engagement between said first arm structure and the support.

3. A device according to claim 1 or claim 2, wherein the retaining means comprises releaseable clamping means between said first arm structure and the support.

4. A device according to any one of claims 1 to 3, wherein both arm structures are mounted about the same pivot but the second arm structure is freely movable, against the bias of the biasing means, relative to the support and first arm structure.

5. A device according to claim 4, wherein the two arm structures are disposed about a rod carried by the support and the retaining means is a nut which may be tightened on the rod to cause the first arm structure only to be retained in a required angular position with respect to the support.

6. A device according to claim 5, wherein the second arm structure is pivotally disposed about a sleeve surrounding the rod, the sleeve ends comprising abutments against which the first arm structure and support will be gripped at the nut is tightened.

7. A device according to claim 5 or claim 6, wherein a shake resistant washer is provided in association with the nut.

8. A device according to any one of claims 1 to 3, wherein the second arm structure is pivotally supported directly by the first arm structure.

9. A device according to claim 8, wherein the pivot axes of the two arm structures lie parallel to one another.

10. A device according to any one of claims 1 to 9, wherein the biasing means acts between the portions of the two arm structures lying on the opposite side of the pivot axis between the two arm structures to that occupied by the gripping flanges.

11. A device according to claim 10, wherein the biasing means comprises a compression spring held between the said portions of the two arm structures.

12. A device according to any one of claims 1 to 11 including an adjustable stop for limiting the movement of the gripping flanges towards one another.

13. A device according to claims 11 and 12, wherein the adjustable stop comprises a nut screwed onto a bolt passing through the said portions of the two arm structures and about which is mounted the compression spring.

14. A device according to any one of claims 1 to 13, wherein the two arm structures are cranked away from the gripping flanges to provide a free space between the arm structures beyond the gripping flanges.

15. A device according to any one of claims 1 to 14, including one or more elongated adjustable arms, each secured at one end to the support or one of the arm structures, and carrying a tool or tool holder at its free end.

16. A device according to claim 15, wherein the tool holder is a crocodile clip or other adjustable gripping member.

17. A device according to claim 15 or claim 1 6, wherein each arm is formed by stiff yet flexible material which will retain the attitude into which it is bent.

18. A workpiece holding device substantially as herein described with reference to the accompanying drawings.