GB2056069A

GB2056069A - Measuring taper and other angles

Info

Publication number: GB2056069A
Application number: GB8021530A
Authority: GB
Original assignee: Coventry City Council
Current assignee: Coventry City Council
Priority date: 1979-07-03
Filing date: 1980-07-01
Publication date: 1981-03-11
Also published as: GB2056069B

Abstract

Method of and apparatus for measuring or checking taper angles or angles of inclination comprises at least two contact elements or edges (10, 20) on axially adjustable members (1, 2), which edges are brought into contact with the surface (30) of a taper bore (3) at corresponding points of contact along the surface (30), the taper angle being determined by the tangent or cotangent relationship between the distances (L) and T. The contact edges (10, 20) may be set or formed a fixed distance (L) apart for checking a particular angle of taper or inclination. A member or members providing the contact elements may be of plate or bar or other form as in Fig. 6 for example. <IMAGE>

Description

SPECIFICATION Taper or like measurement The object of this invention is to provide an improved method of and apparatus or device for the measurement or checking of a taper angle or angles or an angle or angles of other inclination and which offers considerable practical advantages as regards simplicity and convenience of use over the known procedure of using balls or rollers of known diameter often in conjunction with gauge blocks.

According to one aspect of the invention the method of measuring or checking a taper angle or angles or an angle or angles of other inclination is characterised by providing at least two contact elements located in relatively stepped formation and bringing them both into contact with a taper or inclined surface at corresponding points of contact along said surface and determining or checking the angle of such taper or inclination from or by the appropriate trigonometrical relationship between the distance apart of said contact elements as measured or pre-set in the direction of their contact application and a predetermined distance by which they are stepped relative to one another at right angles to said distance apart.

According to a further aspect of the invention apparatus or a device for measuring or checking a taper angle or angles or an angle or angles of other inclination is characterised by means providing at least two contact elements located in relatively stepped formation or capable of being adjusted or set to such formation and adapted to be brought both into contact with a taper or inclined surface at corresponding points of contact along said surface whereby the angle of such taper or inclination can be determined or checked from or by the appropriate trigonometrical relationship between the distance apart of said contact elements as measured or pre-set in the direction of their contact application and a predetermined distance by which they are stepped relative to one another at right angles to said distance apart.

In practice and particularly for enabling taper angles to be readily measured or checked, the construction and arrangement of apparatus or a device for such purpose may be as follows, reference being had to the accompanying drawings in which: FIGURE 1 is an axial plane section of the device in use in measuring or checking an internal taper angle of a bore, FIGURE 2 is a similar view showing the apparatus in use in measuring the angle of an external taper or conical form, FIGURE 3 is a detail axial plane section showing a locking screw arrangement, FIGURE 4 is a detail view on an enlarged scale showing a refinement, FIGURE 5 is a detail view showing the device used for measuring inclination, e.g. of a dovetail formation, FIGURE 6 is a side elevation of a developed form of the device, and FIGURES 7 and 8 show an alternative form of the device for measuring the relative inclination of surfaces.

Referring to FIGURE 1, the device consists of two concentric and relatively slidable rigid tubular members of which the inner tube 1 is an accurate fit within the outer tube 2 and both tubes are preferably of the same known wall thickness, (e.g.

1 mm).

The leading peripheral edges of the tubes 1, 2 provide contact elements 10, 20 for contact with the wall 30 of a taper bore 3 in the manner shown.

On application of the device in the direction of the arrow A required contact is obtained by relative axial movement or adjustment of the tubes until full contact of both elements or edges 10, 20 is fully obtained with the wall 30 of the taper bore 3 at the smallest possibie diameter in each case and which then automatically results in alignment of the axis of the tubes 1, 2 with that of the taper bore 3. Thus there is not need for actual reference to the axis of the bore 3 or other datum face.

The tubes 1, 2 are then locked against relative axial movement such as by a locking screw 4 as shown in FIGURE 3 in which the screw 4 is threaded through a ring 5 about the outer tube 2 and passes through a hole 24 in the latter for clamping contact with the inner tube 1. Other suitable means may be employed for locking or retaining the tubes 1, 2 in the adjusted condition including friction means.

On withdrawal of the locked device, the axial distance L which the inner tube 1 protrudes beyond the leading end of the outer tube 2, is measured and together with the known wall thickness T of the outer tube 2 enables the tangent of half the taper angle to be readily calculated apd thus the value of the whole or included taper angle ()itself. Thus: 0 T Thn---- 2 L Cotangent calculation may be followed if desired.

Referring to FIGURE 2 a similar but converse procedure is followed in the measurement or checking of external taper or conical forms where axial alignment is first obtained by full contact of the leading inner peripheral edges 11, 22 of the tubes 1, 2 with the external taper or conical part 6 to be measured or checked and by appropriate axial adjustment of the tubes 1,2. After locking the tubes 1, 2 against axial movement they are withdrawn from the part 6 and the axial distance L by which the outer tube 2 extends beyond the inner tube 1 is measured where again the tangent of half of the taper angle and the included taper angle O itself can be calculated from the axial or linear distance L and the known wail thickness T of the inner tube 1.

As will be appreciated from the foregoing, the use of two co-axial tubes 1 , 2 of the same wall thickness enables both internal and external taper angles to be readily measured but, more particularly where only internal taper angles are to be measured, the inner member 1 may consist of a solid pin or rod. In the case of a pin or rod the leading end can be recessed to receive and accommodate an external taper part.

It is also desirable to make the outer tube 2 and the inner tube or member 1 identical in length to facilitate measurement of the axial displacement especially in the case of external taper or conical angle measurement shown in FIGURE 2.

In a refinement shown in FIGURE 4 the leading ends of the tubes 1,2 are rounded in a semicircular and identical manner at 101 and 202 respectively to provide in effect cylindrical contact with the wall 30 of a taper bare 3 (or with an external taper or conical part 6), the procedure as regards measuring the relative axial displacement of the tubes 1, 2 and calculation of the taper angle o being the same as that already described. The relationship of the axial or linear distance L and tube wall thickness T to the centres of semicircular curvature of the leading ends 101,202 being indicated in FIGURE 4.

As shown in FIGURE 5 the device may again be used in the same manner for measuring or checking the inclination of one surface S relative to another S 1 such as the measuring or checking of internal or external dovetail formations, e.g. of slideways. Here again automatic location of the device is obtained on full contact of the edges 10, 20 with the surfaces S, S1.

For checking purposes the displacement of the tubes 1, 2 may be pre-set to provide a gauge whereby indication of correct taper angle is given by full seating of the leading edges 10,20; 11, 22 or 101, 202 with the taper bore 3 or formation 6 being checked. On such contact relative rocking movement of the device should not be possible.

Particularly for checking a large volume of components having a taper bore or formation or other surface inclination the gauge may be produced in one piece from the solid by suitable machining to provide the contact elements or edges 10, 20 or 1 22 and clearance opening at the leading end for external taper work.

However, for most purposes, the use of accurately produced tubes 1, 2 or outer tube and inner pin meets most requirements. Thus a set of inter-fitting tubes from 6 mm to 24 mm outside diameter each with a wall thickness of 1 mm and selected as required would cater for a wide range of taper angle measurement. However, it is to be understood that these figures are given by way of practical example only and may be varied according to requirements.

In addition to the advantages of ease and convenience of use, the compact nature of the device invariably enables a component or part to be measured or checked for taper bore angle or angle of other inclination when in situ, e.g. in a machine tool so that removal of the component is not necessary. Measurement or checking of the machining of a workpiece is thus greatly facilitated.

Referring to FIGURE 6 a development form of the device or gauge is shown in which the inner member or pin 61 and the outer tubular member or body 62 are each provided with a head 610, 620 respectively providing contact edges 611, 622 shown in contact with the wall 30 of a taper.

bore 3. The contact edges 611,622 may be radiussed both to a uniform extent.

The rear head 620 is of greater diameter than the leading head 610 by a radial distance corresponding to the predetermined or fixed stepped distance T whilst the head 64 is shown recessed at 621 to accommodate the head 610 when retracted therein.

The outer tubular member or body 62 is also shown conveniently receiving a clamping screw 4 for locking the members 61, 62 after adjustment or after pre-setting the device for taper checking purposes.

For taper bore measurement or checking the heads 610 and 620 are of round cross section but they may be of square, rectangular or other form, e.g. for engagement with flat taper or inclined surfaces.

In this or any other of the embodiments of the invention herein described the contact edges may be rounded to a part cylindrical form or to any other suitable uniform curvature.

It will be appreciated that apparatus or devices embodying the invention may be developed in various ways beyond the basic arrangements described above and, for example, the outer tube 2 and inner tube 1 or pin may be adjustable for relative axial movement by screw means such as micrometer screw mechanism whereby their relative axial displacement can be readily and accurately read off in determining the distance L.

In further developments relative displacement of the tubes 1,2 or outer tube and inner pin may be arranged to operate a dial indicator or clock gauge or digital readout means or the like.

In an electrical or electronic indicating system the tubes 1,2 may be insulated relative to one another so as to serve as a transducer or variable capacitor in such a system. Insulated contact with metal taper or inclined surfaces would be necessary at the leading edges 10, 20 and 11, 22.

Thus the tubes 1, 2 may be mainly of electrically non-conductive material carrying electrically conductive parts in circuit with the indicating system.

In a further development two or more outer concentric tubes about an inner tube or pin may be employed, e.g. for measuring taper bores or formations of considerable length, i.e. in ascertaining uniformity of the taper angle or measuring required variation of taper angle.

Whereas the use of concentric tubular members or at least one tubular member and an inner pin is convenient in practice for the measurement of taper bores or formations or other inclination and at the same time automatically obtaining the required axial or similar alignment, other arrangements of relatively movable members may be employed for providing contact elements or edges in a similar manner to that already described. Thus in FIGURE 7 the device consists of a pair of bars or plates 51, 52 which are relatively slidable and provide contact elements 100, 200 at their leading edges, the thickness T of at least one bar 52 or preferably both bars 51, 52 being of a known value so that the angle of inclination can be calculated in the manner already described from the known thickness T and measurement of the linear displacement L.

The device in this form can be used for measuring the inclination of one surface S relative to the other S1 by causing one bar 51 to lie flat against one surface S1 and effecting contact of the leading edges 1 00, 200 with the other surface S, those surfaces of the bar 51 between the surface S1 and the upper bar 52 being accurately parallel. Here again, means, such as screw or friction means, should be provided for locking or retaining the bars 51, 52 together after linear adjustment and which may also serve to retain the bars as an assembly in firm sliding contact with one another. A pre-set or solid form of such an arrangement may be provided as a checking gauge.

It will be also appreciated that the device of FIGURE 6 is capable of use in measuring obtuse angles of relative inclination as per FIGURE 8 in which a locking screw 40 is shown and a spacing shim 55.

Claims

1. Method of measuring or checking a taper angle or angles or angle or angles of other inclination characterised by providing at least two contact elements located in relatively stepped formation and bringing them both into contact with a taper or inclined surface at corresponding points of contact along said surface and determining or checking the angle of such taper or inclination from or by the appropriate trigonometrical relationship between the distance (L) apart of said contact elements as measured or pre-set in the direction (A) of their contact application and a predetermined distance (T) by which they are stepped relative to one another at right angles to said distance (L) apart.

2. Apparatus or a device for measuring or checking a taper angle or angles or an angle or angles of other inclination characterised by means providing at least two contact element located in relatively stepped formation or capable of being adjusted or set to such formation and adapted to be brought both into contact with a taper or inclined surface at corresponding points of contact along said surface whereby the angle of such taper or inclination can be determined or checked from or by the appropriate trigonometrical relationship between the distance (L) apart of said contact elements as measured or pre-set in the direction (A) of their contact application and a predetermined distance (T) by which they are stepped relative to one another at right angles to said distance (L) apart.

3. Apparatus or a device according to claim 2 wherein the contact elements are provided by relatively stepped edges of a member or of an assembly of two or more members.

4. Apparatus or a device according to claim 3 wherein the members of a said assembly thereof are capable of relative linear movement for setting or adjusting the contact elements a said distance (L) apart in the direction (A) of contact application.

5. Apparatus or a device according to claim 4 wherein the members of a said assembly are relatively slidable.

6. Apparatus or a device according to claim 4 or 5 wherein means is provided for releasably retaining the members of a said assembly in a relative linear position to which they are adjusted or set.

7. Apparatus or a device according to any of claims 4 to 6 wherein the members of a said assembly thereof comprise an inner member and at least one outer tubular member thereabout.

8. Apparatus or a device according to claim 7 wherein the inner member is tubular or at least hollow adjacent that end thereof provided with a said contact element or edge.

9. Apparatus or a device according to claim 7 or 8 wherein two or more outer concentric tubular members are provided about the inner member for increased range of taper or inclination angle measurement or checking or for simultaneously measuring or checking variation in the angle of taper or inclination.

10. Apparatus or a device according to claim 3 wherein the distance (L) apart and stepped relationship (T) of the contact elements or edges are fixed for measuring or checking a particular taper angle or angle of inclination.

11. Apparatus or a device according to claim 10 wherein the contact elements or edges of fixed distance (L) apart and stepped relationship (T) are provided by a suitably formed member.

1 2. Apparatus or a device according to any of claims 3 to 11 wherein the member or each member of an assembly thereof is of round cross section especially for measuring or checking taper bores or external conical formations and also for measuring or checking acute angle relative inclination.

13. Apparatus or a device according to claim 4 or to any of the preceding claims appendant thereto wherein the members of a said assembly thereof are of equal lenoth from the contact elements or edges thereof.

14. Apparatus or a device according to any of claims 2 to 12 wherein the contact elements or edges are of rounded form.

1 5. Apparatus or a device according to claim 3 or to any of the preceding claims appendant thereto wherein the member, or each member of a said assembly thereof, is provided with a head on which the contact element or edge is provided.

16. Apparatus or a device according to any of claims 3 to 6 wherein the member, or each member of a said assembly thereof, is of bar or plate form.

17. Apparatus or a device according to claim 4 or to any of the preceding claims appendant thereto wherein the relatively movable members of a said assembly thereof are arranged for screw operation for such movement such as by micrometer screw means.

18. Apparatus or a device according to claim 4 or to any of the preceding claims appendant thereto wherein the relatively movable members of a said assembly thereof are arranged to actuate indicator means as a dial indicator gauge.

19. Apparatus or a device according to claim 4 or to any of the preceding claims appendant thereto wherein at least co-operating parts of the relatively movable members of a said assembly thereof are electrically insulated from one another so as to serve as a transducer or a variable capacitor in an electrical or electronic measurement or checking indicating system.

20. Method of measuring or checking a taper angle or angles or an angle or angles of other inclination substantially as herein described with reference to the accompanying drawings.

21. Apparatus or a device for measuring or checking a taper angle or angles or an angle or angles of other inclination substantially as herein described with reference to any of the several embodiments thereof shown in the accompanying drawings.