GB2129131A - Caliper gauge - Google Patents

Abstract

Measuring apparatus comprises a C-shaped caliper 1 carrying a fixed anvil 6 on one arm 3 and a movable anvil 7 on the other arm 4 so as to make measurements on a workpiece 5, the movable anvil 7 having a transducer 8 associated directly with it so as to produce an output corresponding to the distance between the anvils, and the caliper being supported in an upright orientation by support means 18 to 23 including resilient means 25, 26 that supports the weight of the caliper and allows it to move vertically to accommodate variations in the height of the workpiece. The caliper is of a one-piece or rigid composite construction and the anvils 6, 7 are such as to give point-to-point measurement, for example by using spherical anvils or cylindrical anvils. Stop means 32 limit the vertical movement of the caliper and support the caliper when not engaging the workpiece. <IMAGE>

Description

SPECIFICATION Caliper gauge This invention relates to apparatus suitable for measuring diameter.

Measuring apparatus according to the invention comprises a C-shaped caliper carrying a fixed anvil on one arm and a movable caliper on the other arm so as to make measurements on a workpiece received between the arms of the caliper, the movable anvil having a transducer associated directly with it so as to produce an output corresponding to the distance between the anvils, and the caliper being supported in an upright orientation by support means including resilient means that supports the weight of the caliper and allows it to move vertically to accommodate variations in the height of the workpiece.

Preferably, the caliper is of a one-piece or rigid composite construction so as to avoid movable joints that could introduce measuring errors. The anvil and associated transducer are the movable elements that make the measurement directly in the measuring plane.

Preferably, the anvils are such as to give pointto-point measurement, for example by using spherical anvils or cylindrical anvils on round section workpieces.

The resilient support means effectively allows a limited floating movement of the caliper so that it can be engaged with the workpiece in a convenient and sensitive manner for maximum accuracy.

Preferably, the caliper is made as narrow as possible so as to allow measurements in restricted locations, and means is provided to make measurements at predetermined axial locations.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows elevation of one embodiment of the invention suitable for measuring diameter, and Figure 2 shows a side elevation of an alternative embodiment of the invention suitable for measuring diameter.

The apparatus illustrated in Figure 1 comprises a C-shaped caliper 1 made from rigid plate material and supported in an upright manner with the cut-out 2 between the upper and lower arms 3, 4 of the caliper opening forwards to engage either side of a cylindrical workpiece 5.

A cylindrical anvil 6 is fixedly mounted on the upper arm 3 with its axis parallel to the plane of the caliper so that it forms a point contact with the workpiece.

A spherical anvil 7 is connected to the end of a transducer 8 that is mounted on the lower arm 4 so as to be vertically adjustable. The body of the transducer is cylindrical and is received as a close fit in a bore in the arm 4 and is clamped in position in the bore by a pair of plates 9, 10 that are located transversely of a transducer 8 in slots 11, 12 in the end of the arm 4 and are held in place by a clamping plate 13 and screw 14. Each of the plates 9, 10 is formed with an arcuate recess 1 5 at one end to engage the transducer body and a peg 16 at the other end to engage a hole 17 in the clamping plate 13. The screw 14 engages a threaded hole 18 between the two slots 11, 12 to clamp the plate 13 in place.

The caliper 1 is resiliently suspended from a sub-frame comprising a pair of brackets 18, 19 interconnected by a bar 20, and this sub-frame is supported on a rigid stand comprising a base 21 and vertical column 22 along which the brackets 18, 19 are slidably adjustable to vary the height of the caliper. A thumb screw 23 is provided in the upper bracket 1 8 and operates on a keyway 24 to clamp the bracket 18 at any desired height along column 22.

The caliper 1 is connected to the sub-frame 1 8-20 by a pair of leaf springs 25 and a pair of tension springs 26. The leaf springs 25 are connected one to the top and one to the bottom of the caliper by clamps 27 and screws 28, and each projects rearwards and is connected to a corresponding bracket 29 on the bar 20 by clamps 30 and screws 31.

The brackets 29 contain the rearward end of the caliper therebetween and each is provided with an adjustable stop 32 to limit resilient floating movement of the caliper. Each stop 32 comprises a screw and lock nut 33, the screw 32 passing through the bracket 29 and clamp 30 and co-operating at its end with a cut-away shoulder 34 on the caliper. A pair of plates 35 are connected to the intermediate portion of each leaf spring, one either side, so as to limit its resilience.

The tension springs 26 are connected to the caliper top and bottom through a lug 36 held by screws 28, and are secured at their outer ends to the brackets 1 8, 19 by screws 37. The tension of the springs 26 is adjusted by clamping the position of the brackets 18, 19 in the bar 20, this being facilitated by grub screw connections 38 therebetween. The tension is normally adjusted so that the caliper lightly engages the lower stop 32.

The upper cylindrical anvil 6 engages and rides up over a workpiece, assisted by its tapered nose, so that the caliper is floating. The transducer is then brought lightly into engagement with the underside of the workpiece to make a diameter measurement.

It will be appreciated that this arrangement can be readily inverted if desired by locating the transducer 1 8 on the upper arm and the cylindrical anvil 6 on the lower arm, and adjusting the tension springs 26 so that the caliper engages the upper stop 32. In both arrangements the transducer is protected from possible impact damage by engagement with the workpiece as the caliper is moved into position.

In operation, the workpiece is supported on a measuring table between centres or on Vee blocks so that its axis lies parallel to the surface of the measuring table. The height of the caliper is adjusted, and the caliper is engaged with the workpiece to make a diameter measurement, the plane of the caliper being perpendicular to the axis of the workpiece. Measurement can be made at different axial locations of the workpiece by moving the stand and caliper axially.

If diameter measurements are to be made at a predetermined distance from a shoulder or thrust face on the workpiece, a locating stud 39 projecting from the side face of the upper arm of the anvil can be engaged with said shoulder or thrust face to space the measuring plane of the anvils the required distance from it. This stud 39 is movable in a bore through the upper arm so as to project from either side face, thereby allowing the caliper to be spaced the required distance from both left and right hand thrust faces. A spring loaded detent 40 is provided to engage the stud 39 to hold it in both positions.

Apparatus as illustrated in Figure 1 would be suitable for measuring the diameter of crankshaft journals, the caliper 1 being made as narrow as possible to suit the journal width.

The transducer diameter, typically 5 mm is the main limiting factor in reducing the caliper width.

An alternative embodiment of the invention is illustrated in Figure 2 in which a different form of sub-frame is used to support the caliper. Instead of the assembly comprising brackets 18, 19, interconnecting bar 20 and brackets 29, a shaped plate 41 is employed having a cut-out 42 corresponding to the space between the brackets 29 in which the rear of the caliper is received. The leaf springs 25 are connected to the shoulders 43 either side of the cut-out 42. The tension springs 26 are connected to screws 44 projecting from the front of the plate 41. The tension of springs 26 could be adjusted by bending the screws, or additional tension adjustment means can be provided.

The plate 41 is supported on the vertical column 22 by a collar 45 connected to the centre of the plate and which is provided with a thumb screw 46.

Claims (13)

1. Measuring apparatus comprising a C-shaped caliper carrying a fixed anvil on one arm and a movable anvil on the other arm so as to make measurements on a workpiece received between the arms of the caliper, the movable anvil having a transducer associated directly with it so as to produce an output corresponding to the distance between the anvils, and the caliper being supported in an upright orientation by support means including resilient means that supports the weight of the caliper and allows it to move vertically to accommodate variations in the height of the workpiece.

2. Measuring apparatus as claimed~in claim 1 in which the caliper is of a rigid construction without movable joints.

3. Measuring apparatus as claimed in claim 2 in which the movable anvil and associated transducer are movable together relative to the caliper.

4. Measuring apparatus as claimed in claim 3 in which the support means comprises a frame assembly including adjustable stops means that limits said vertical movement of the caliper.

5. Measuring apparatus as claimed in claim 4 in which the resilient means is such that the caliper assumes a position in engagement with stop means ready for engagement with the workpiece so that engagement of said fixed anvil with the workpiece moves the caliper out of engagement with said stop means into a resiliently supported floating condition.

6. Measuring apparatus as claimed in claim 5 in which said stop means comprises lower stop means against which the caliper engages under its own weight, and in which the fixed anvil is the upper anvil that rides over the workpiece to lift the caliper into said resiliently supported floating condition.

7. Measuring apparatus as claimed in claim 5 in which said stop means comprises upper stop means against which the caliper engages under the action of said resilient means, and in which the fixed anvil is the lower anvil that rides beneath the workpiece to lower the caliper into said resiliently supported floating condition.

8. Measuring apparatus as claimed in any one of claims 4 to 7 in which the resilient means comprises a pair of leaf springs that are connected to said caliper to project rearwards therefrom at vertically spaced points and which are connected at their rear ends to a frame assembly.

9. Measuring apparatus as claimed in claim 8 in which the resilient means further comprises a pair of tension springs each connected between the caliper and the frame assembly to act against one another vertically.

10. Measuring apparatus as claimed in claim 8 or 9 in which the leaf springs are connected to the frame assembly through a pair of brackets between which the rear end of the caliper lies so as to be engaged by said stop means mounted on said brackets.

11. Measuring apparatus as claimed in any one of claims 4 to 10 in which the support means comprises said frame assembly and a rigid support member in which the frame assembly is vertically adjustably supported.

12. Measuring apparatus as claimed in any one of the preceding claims in which the anvils have curved abutment surfaces for engagement with the workpiece so as to give point contact.

13. Measuring apparatus substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying drawings.