Clamping:
To restrain the workpiece completely a clamping device is required in addition to locating device and jigs and fixtures. A clamping device holds the workpiece securely in a jig or fixture against the forces applied over it during on operation. Clamping device should be incorporated into the fixture, proper clamp in a fixture directly influence the accuracy and quality of the work done and production cycle time. Basic requirement of a good clamping device are listed below :
(a) It should rigidly hold the workpiece.
(b) The workpiece being clamped should not be damaged due to application of clamping pressure by the clamping unit.
(c) The clamping pressure should be enough to over come the operating pressure applied on the workpiece as both pressure act on the workpiece in opposite directions.
(d) Clamping device should be capable to be unaffected by the vibrations generated during an operation.
(e) It should also be user friendly, like its clamping and releasing should be easy and less time consuming. Its maintenance should also be easy.
(f) Clamping pressure should be directed towards the support surfaces or support points to prevent undesired lifting of workpiece from its supports.
(g) Clamping faces should be hardened by proper treatments to minimize their wearing out.
(h) To handle the workpieces made of fragile material the faces of clamping unit should be equipped with fibre pads to avoid any damage to workpiece.
Different Types of Clamps:
Different variety of clamps used with jigs and fixtures are classified into different categories are discussed here.
Strap Clamp:
This is also called edge clamp. This type clamping is done with the help of a lever pressure acting as a strap on the workpiece. Different types of strap clamps are discussed below.
Heel Clamp:
The simple form of a heel clamp is shown in Figure 4.9. Rotation of the clamp in clockwise direction is prevented and it is allowed in anticlockwise direction. For releasing the workpiece the clamping nut is unscrewed. The free movement in anticlockwise direction takes place before un-securing the nut to release the workpiece.
Bridge Clamp:
The bridge clamp is illustrated in Figure 4.10. It applies more clamping pressure as compared to heel clamp. The clamping pressure experienced by the workpiece depends on the distances „x‟ and „y‟ marked in the Figure 4.10. To release the workpiece the nut named as clamping nut is unscrewed. The spring lifts the lever to release the workpiece.
Edge Clamp or Side Clamp:
A side clamp is also known as edge clamp. In this case the surface to be machined is always clamped above the clamping device. This clamping device is recommended for fixed length workpiece. The clamping device is illustrated in Figure 4.11. Releasing and clamping of the workpiece can be accomplished by unscrewing and screwing of the clamping nut respectively.
Screw Clamp:
The screw clamp is illustrated in Figure 4.12. It is also known as clamp screw. This clamping apply pressure directly on the side faces of the workpiece. There is a floating pad at their end to serve the following purposes :
(a) It prevents displacement of workpiece and slip.
(b) It prevents denting of clamping area of workpiece.
(c) The available cushion prevents deflection of screw.
In addition to the above there are some disadvantages associated with this method. The clamping pressure largely depends on the workpiece, it varies from one workpiece to other. It is more time consuming and more efforts are required.
Latch Clamp:
Latch clamps are used to clamp the workpiece, the clamping system is normally locked with the help of a latch provided. To unload the workpiece the tail end of the latch is pushed that causes the leaf to swung open, so releasing the workpiece. Here time consumed in loading and unloading is very less as no screw is tightened but clamping pressure is not so high as in other clamping devices. Life of this type of clamping device is small.
Equalizing Clamps:
Equalizing clamp is illustrated in Figure 4.13. It is recommended to apply equal pressure on the two faces of the work. The pressure applied can be varied by tightened or loosening the screw provided for the purpose.
Published by Ravindra.K(Mechanical Engineering)
To restrain the workpiece completely a clamping device is required in addition to locating device and jigs and fixtures. A clamping device holds the workpiece securely in a jig or fixture against the forces applied over it during on operation. Clamping device should be incorporated into the fixture, proper clamp in a fixture directly influence the accuracy and quality of the work done and production cycle time. Basic requirement of a good clamping device are listed below :
(a) It should rigidly hold the workpiece.
(b) The workpiece being clamped should not be damaged due to application of clamping pressure by the clamping unit.
(c) The clamping pressure should be enough to over come the operating pressure applied on the workpiece as both pressure act on the workpiece in opposite directions.
(d) Clamping device should be capable to be unaffected by the vibrations generated during an operation.
(e) It should also be user friendly, like its clamping and releasing should be easy and less time consuming. Its maintenance should also be easy.
(f) Clamping pressure should be directed towards the support surfaces or support points to prevent undesired lifting of workpiece from its supports.
(g) Clamping faces should be hardened by proper treatments to minimize their wearing out.
(h) To handle the workpieces made of fragile material the faces of clamping unit should be equipped with fibre pads to avoid any damage to workpiece.
Different Types of Clamps:
Different variety of clamps used with jigs and fixtures are classified into different categories are discussed here.
Strap Clamp:
This is also called edge clamp. This type clamping is done with the help of a lever pressure acting as a strap on the workpiece. Different types of strap clamps are discussed below.
Heel Clamp:
The simple form of a heel clamp is shown in Figure 4.9. Rotation of the clamp in clockwise direction is prevented and it is allowed in anticlockwise direction. For releasing the workpiece the clamping nut is unscrewed. The free movement in anticlockwise direction takes place before un-securing the nut to release the workpiece.
Bridge Clamp:
The bridge clamp is illustrated in Figure 4.10. It applies more clamping pressure as compared to heel clamp. The clamping pressure experienced by the workpiece depends on the distances „x‟ and „y‟ marked in the Figure 4.10. To release the workpiece the nut named as clamping nut is unscrewed. The spring lifts the lever to release the workpiece.
Edge Clamp or Side Clamp:
A side clamp is also known as edge clamp. In this case the surface to be machined is always clamped above the clamping device. This clamping device is recommended for fixed length workpiece. The clamping device is illustrated in Figure 4.11. Releasing and clamping of the workpiece can be accomplished by unscrewing and screwing of the clamping nut respectively.
Screw Clamp:
The screw clamp is illustrated in Figure 4.12. It is also known as clamp screw. This clamping apply pressure directly on the side faces of the workpiece. There is a floating pad at their end to serve the following purposes :
(a) It prevents displacement of workpiece and slip.
(b) It prevents denting of clamping area of workpiece.
(c) The available cushion prevents deflection of screw.
In addition to the above there are some disadvantages associated with this method. The clamping pressure largely depends on the workpiece, it varies from one workpiece to other. It is more time consuming and more efforts are required.
Latch Clamp:
Latch clamps are used to clamp the workpiece, the clamping system is normally locked with the help of a latch provided. To unload the workpiece the tail end of the latch is pushed that causes the leaf to swung open, so releasing the workpiece. Here time consumed in loading and unloading is very less as no screw is tightened but clamping pressure is not so high as in other clamping devices. Life of this type of clamping device is small.
Equalizing Clamps:
Equalizing clamp is illustrated in Figure 4.13. It is recommended to apply equal pressure on the two faces of the work. The pressure applied can be varied by tightened or loosening the screw provided for the purpose.
Published by Ravindra.K(Mechanical Engineering)
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