GB1584445A

GB1584445A - Work holders

Info

Publication number: GB1584445A
Application number: GB18116/76A
Authority: GB
Original assignee: British Cast Iron Research Association; Bcira
Current assignee: British Cast Iron Research Association; Bcira
Priority date: 1977-06-30
Filing date: 1977-06-30
Publication date: 1981-02-11
Also published as: FR2429650B3; DE2826519A1; FR2429650A1

Description

(54) WORK HOLDERS (71) We, BCIRA, a British Company of Alvechurch, Birmingham B48 7QB, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a work holder for supporting and locating a workpiece of arbitrary or irregular shape while it is being subjected to some kind of treatment or action. For example metal castings, after removal from their moulds generally require to be cleaned by shot-blasting or wire brushing and then may have to be fettled with a hand-held tool to remove runners, feeders.

and flash. Small castings can be brought into engagement with a stand-mounted grinding wheel or a bandsaw. Larger castings, however, too heavy or awkward to be picked up by hand, have to be clamped on a bench or platform and engaged by hand-held tools, including, for example suspended flexibleshaft grinders, and so need to be held securely. Power-driven tilting and rotating stands are known for this purpose but are expensive, and the work-piece has to be clamped to the faceplate or mandrel of the stand before treatment and unclamped afterwards, steps which take time.

Regardless of whether or not a powerdriven stand is employed, the castings still have to be brought to the fettling station or booth on, for example, skid plates, wheeled pallets, a roller track or fork-lift trucks, and then have to be man-handled or lifted with a mechanical hoist to place them in the fettling jig.

The aim of the invention is to provide a new and simple way of rapidly and easily supporting and locating a workpiece of arbitrary or irregular shape during treatment. According to the invention a work holder for this purpose comprises a horizontal table through which protrudes a twodimensional array of mutually spaced-apart vertical rods, each rod being movable independently of the others in a vertical direction, means being provided for urging all the rods upwards into contact with a workpiece positioned over the table, and means further being provided for clamping each rod frictionally in the position it has then reached.

Thus, to locate a workpiece, virtually regardless of its shape, the workpiece is placed on or over the table and then the rods are all moved towards it until their tips, or at least their side surfaces, engage the workpiece, then the rods are all locked in position. The workpiece is thereby securely located in position for its subsequent treatment. At the end of the treatment the rods are retracted to a rest position or starting position to allow the workpiece to be removed.

Alternatively the rods may simply be urged upwards by springs.

The invention will now be further described by way of example with reference to the accompanying drawings, in which : Figure 1 is a diagrammatic section through an example of a work holder according to the invention, shown holding a casting ready for fettling; Figure 2 shows a detail, to a larger scale, of the holder on Figure 1; Figures 3A to 3G shows successive stages in the progress of a casting through the work holder of Figure 1; and Figure 4 is a perspective view of a work holder similar to that of Figure 1, shown engaging a workpiece mainly around its periphery.

The work holder illustrated in Figures 1, 2 and 3 has been designed primarily to hold large iron castings after they have been removed from their moulds and now require to be fettled. In a general iron foundry castings of all sorts of shapes and sizes may be produced in the same casting shop and so it is impracticable to provide special jigs for holding each type of casting and anyway the variations in dimensions and in the presence or absence of flash as between one casting and another nominally identical one make the use of close-fitting jigs and clamps impossible.

Accordingly we provide a table 1 having a horizontal upper surface 2 penetrated by an array of vertical rods 3. Each rod, in the example shown, forms the piston rod of a respective pneumatic cylinder 4, being secured to a piston 5, and is guided in a lower surface 6, as well as the upper surface 2, of the table 1. When a body such as the casting indicated at 7 is placed on the table (the rods at this stage being fully retracted) and then air is admitted to cylinders of at least those rods over which the body lies, the rods will rise to locate the body and possibly tilt it to a stable position as shown.

There may be selector valves (not shown) to select the cylinders for only the rods over which the body lies, but if too many rods rise clear of the body and reach the upper limits of their travels they can be individually retracted by appropriate valves. For example it could be arranged that any rods which reach the upper limit of their travel, indicating that they have missed the body, are retracted automatically.

When the body 7 is in a stable position, supported by a substantial number of rods, clamps 8 are actuated to lock the rods in position. The means for actuating the clamps are shown in Figure 2. Between each pair of adjacent rods is an inflatable flexible tube 9 arranged in a casing 10 and engaging a pair of locking buttons 11. When air under pressure is admitted to the tube 9 it forces the buttons 11 against the adjacent rods 3 to hold the rods by friction in the positions they then occupy. The pneumatic pressure in the cylinders 4 can then be released.

On completion of the treatment, i.e. the fettling operation, the clamps 8 are released and the rods 3 are retracted, either by gravity or by the admission of air to the upper ends of the cylinders 4 (where these are double-acting). The casting 7 can then be removed.

To facilitate the treatment further the entire table 1 is vertically movable on fluidpressure rams 12. In the retracted position of the table its upper surface 2 is flush with the surface 13 of the surrounding floor, the rams being received in a pit 14 of appropriate dimensions. Thus a heavy casting only has to be brought onto the table 1 at floor level and all the usual means of transporting it such as roller tracks, fork-lift trucks and pallets, can be employed. Then when the casting is located and held by the rods 3 the rams 12 are energised to raise the table 1 and the casting 7 to a convenient height for working on. At the end of the operation the table is lowered again and the casting removed horizontally.

The sequence of operations described in the paragraph above is illustrated in Figures 3A to 3G. Also shown in those Figures is a booth 15 forming an enclosure that confines the dust created by the fettlirig process.

It will be seen that the lower part of the booth is open at the sides so that the castings can be freely brought to the table and removed from it but that when the table rises the table itself seals off the booth to restrict the escape of dust and noise. As shown in Figure 1 there are slots 16 in the upper surface 2 of the table, leading to ducts 17 to suck away the dust and polluted air. The surface 1 may also have balls or rollers (not shown) set in it to faciliatate the movement of the castings on and off the table.

It will be understood that the rams 4 could be hydraulic instead of pneumatic and indeed, within the scope of the invention, they could be replaced by springs.

Although the members 3 have been referred to as rods they could be hollow, i.e.

the form of tubes and the term 'rod' is in- tended to include this. Also the rods could be used to locate the body 7 by engagement of the sides rather than the tips of at least some of them. Figure 4 shows an irregularly shaped casting 71 located in such a manner on a table 11 having hollow rods 31. Those which are free to do so rise to their full extents around the casting and locate it securely, although at the cost of a certain amount of restriction on access to the casting.

WHAT WE CLAIM IS:- 1. A work holder for supporting and locating a workpiece of arbitrary or irregular shape during treatment comprising a horizontal table through which protrudes a twodimensional array of mutually spaced-apart vertical rods, each rod being movable independently of the others in a vertical direction, means being provided for urging all the rods upwards into contact with a workpiece positioned over the table and means further being provided for clamping each rod frictionally in the position it has then reached.

2. A work holder according to claim 1 in which the means for urging the rods upwards comprise fluid-pressure rams.

3. A work holder according to claim 2 in which the rods are themselves formed by piston rods of the rams, which are pneu matic.

4. A work holder according to claim 1 in which the means for urging the rods upwards comprise springs.

5. A work holder according to any one of claims 1 to 4 in which the clamping means are actuated by fluid pressure.

6. A work- holder according to claim 5 in which the clamping means comprise inflatable ffexiblC tubes which force clamping members laterally against the rods.

7. A work holder according to any one of claims 1 to 6 in which the table is itself

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. a horizontal upper surface 2 penetrated by an array of vertical rods 3. Each rod, in the example shown, forms the piston rod of a respective pneumatic cylinder 4, being secured to a piston 5, and is guided in a lower surface 6, as well as the upper surface 2, of the table 1. When a body such as the casting indicated at 7 is placed on the table (the rods at this stage being fully retracted) and then air is admitted to cylinders of at least those rods over which the body lies, the rods will rise to locate the body and possibly tilt it to a stable position as shown. There may be selector valves (not shown) to select the cylinders for only the rods over which the body lies, but if too many rods rise clear of the body and reach the upper limits of their travels they can be individually retracted by appropriate valves. For example it could be arranged that any rods which reach the upper limit of their travel, indicating that they have missed the body, are retracted automatically. When the body 7 is in a stable position, supported by a substantial number of rods, clamps 8 are actuated to lock the rods in position. The means for actuating the clamps are shown in Figure 2. Between each pair of adjacent rods is an inflatable flexible tube 9 arranged in a casing 10 and engaging a pair of locking buttons 11. When air under pressure is admitted to the tube 9 it forces the buttons 11 against the adjacent rods 3 to hold the rods by friction in the positions they then occupy. The pneumatic pressure in the cylinders 4 can then be released. On completion of the treatment, i.e. the fettling operation, the clamps 8 are released and the rods 3 are retracted, either by gravity or by the admission of air to the upper ends of the cylinders 4 (where these are double-acting). The casting 7 can then be removed. To facilitate the treatment further the entire table 1 is vertically movable on fluidpressure rams 12. In the retracted position of the table its upper surface 2 is flush with the surface 13 of the surrounding floor, the rams being received in a pit 14 of appropriate dimensions. Thus a heavy casting only has to be brought onto the table 1 at floor level and all the usual means of transporting it such as roller tracks, fork-lift trucks and pallets, can be employed. Then when the casting is located and held by the rods 3 the rams 12 are energised to raise the table 1 and the casting 7 to a convenient height for working on. At the end of the operation the table is lowered again and the casting removed horizontally. The sequence of operations described in the paragraph above is illustrated in Figures 3A to 3G. Also shown in those Figures is a booth 15 forming an enclosure that confines the dust created by the fettlirig process. It will be seen that the lower part of the booth is open at the sides so that the castings can be freely brought to the table and removed from it but that when the table rises the table itself seals off the booth to restrict the escape of dust and noise. As shown in Figure 1 there are slots 16 in the upper surface 2 of the table, leading to ducts 17 to suck away the dust and polluted air. The surface 1 may also have balls or rollers (not shown) set in it to faciliatate the movement of the castings on and off the table. It will be understood that the rams 4 could be hydraulic instead of pneumatic and indeed, within the scope of the invention, they could be replaced by springs. Although the members 3 have been referred to as rods they could be hollow, i.e. the form of tubes and the term 'rod' is in- tended to include this. Also the rods could be used to locate the body 7 by engagement of the sides rather than the tips of at least some of them. Figure 4 shows an irregularly shaped casting 71 located in such a manner on a table 11 having hollow rods 31. Those which are free to do so rise to their full extents around the casting and locate it securely, although at the cost of a certain amount of restriction on access to the casting. WHAT WE CLAIM IS:-

1. A work holder for supporting and locating a workpiece of arbitrary or irregular shape during treatment comprising a horizontal table through which protrudes a twodimensional array of mutually spaced-apart vertical rods, each rod being movable independently of the others in a vertical direction, means being provided for urging all the rods upwards into contact with a workpiece positioned over the table and means further being provided for clamping each rod frictionally in the position it has then reached.

movable vertically between a lower loading position and an upper working position.

8. A work holder according to claim 7 in which, in its working position, the table substantially closes off a chamber enclosing a region above the table that is to receive the workpiece, whereas in its loading position there is open access at the sides of the table for the horizontal introduction and removal of the workpiece.

9. A work holder according to claim 1 or claim 2 in which the table incorporates balls or rollers that facilitate horizontal movement across it for loading and unloading.

10. A work holder for supporting and locating a workpiece of arbitrary or irregular shape during treatment, substantially as described with reference to Figures 1 to 3 of the accompanying drawings.