GB2323051A - Articulared diamond or like dressing tool arrangement - Google Patents

Abstract

In an articulated diamond tool arrangement for forming, dressing or trueing a grinding wheel (15) having a formed periphery (150), the or each diamond tool (14) is radially carried by the head (11) of a shaft journalled in a bearing support and operable for movement along a path (P) corresponding to, and spaced from, the profile of the grinding wheel peripheral form (150). Angular movement of the shaft (10) in the bearing support effects articulation of the diamond tool (14) and so enables it to be presented substantially normal to, and in contact with, the profile of the peripheral form (150) during or throughout a forming or like operation. For a robust and stable arrangement the head (11) is close to or against the bearing support (12). More than one such tool (14) can be carried by the head (11).

Description

Title: Articulated diamond or like tool arrangement This invention has reference to the forming, dressing or trueing of grinding wheels having a formed periphery which may be of annular single or multi-ribbed formation.

Diamond or like tools for the above forming or like purpose usually consist of a cylindrical holder having a central tip of diamond or other very hard material at an operative end of the holder, or the tool may consist of a rotary disc having a multiplicity of diamonds or diamond particles or similar material set around its periphery.

In order to follow the profile of a grinding wheel form the diamond or like tool (or more than one such tool) is or are mounted for articulated movement so as to follow a required path about and in contact with the form.

Hitherto current articulated diamond tool arrangements provide the centre of the radius of the diamond tip on the centre line of articulation and usually it is necessary to follow exacting and time consuming setting procedure to ensure that such location of the diamond tip is precisely correct. Currently and widely used articulation arrangements for such procedure are of the "swan neck" arm construction as shown in prior art Figures A to D of the accompanying drawings, reference being also made to Figure E.

Thus in Figure A a shaft 1 journalled in bearing support 2 has an eccentric swan neck arm 3 extending in an offset axially parallel manner from an end or head of the shaft 1. The outer or free end part of the arm 3 carries a holder 40 of a diamond tool 4 at right angles to the arm 3 so as to extend radially from it for location of the diamond tip 44 on the axis 0 of articulation of the shaft 1. The diamond tip 44 is also positioned vertically under the centre of rotation of the grinding wheel 5 (Figure B) so that, together with the axial location, an offset slender arm 3 is necessary to accommodate the grinding wheel periphery 50. The arm 3 may also have to accommodate equipment such as a coolant nozzle 6 as shown in Figure B.

The slender arm 3 lacks rigidity and this disadvantage is aggravated where a longer arm 3 is necessary as also shown in Figure B, to accommodate a larger wheel 5 and the nozzle 6.

Diamond wear is a consideration and often two diamond tools 4 are employed as shown in Figure C, i.e. for roughing and finish forming of a grinding wheel which requirement further aggravates the problem.

Referring at this point to Figure E the use of a rotary disc diamond tool 7 can be advantageous having regard to the nature of a grinding wheel. Thus grinding wheels are of relatively soft material but become apparently hard when rotated at high speed for an effective grinding action. By rotating the diamond disc 7 in a sympathetic or matching direction and at a peripheral speed approaching that of the grinding wheel 5 the latter then becomes, in effect, of a soft condition to the peripheral diamond or diamond particles 70 of the disc 7 so that diamond wear is greatly reduced.

However, the mounting of a motor driven diamond disc 7 on a swan neck arm 3 (Figure D) creates further problems as regards stability and accommodating grinding wheel diameter, the coolant nozzle 6 and any other equipment. Furthermore, the arrangement often necessitates outer bearing support 8 for the swan neck arm 3. As well as such complexity the arrangement takes up work table grinding area thus reducing the capacity of the grinding machine. This is despite the fact that the actual articulating mechanism including the shaft 1 and bearing 2 is positioned outside the normal grinding area.

The object of the invention is to provide an improved articulated arrangement of one or more diamond or like tools which is of robust and compact construction, which is readily set up and operated and which is also of minimum hindrance in the grinding area of a grinding machine. This and other practical advantages and features of the invention will be apparent from the following description.

In accordance with this invention an articulated diamond or like tool arrangement for forming, dressing or trueing a grinding wheel having a formed periphery is characterised by a shaftjoumalled in bearing support structure and which are together operable for movement along a path corresponding to and spaced from the profile of the peripheral form of the grinding wheel, a concentric end part or head of the shaft carrying at least one diamond or like tool for angular movement with the shaft whereby articulation of the tool so provided enables it to be presented substantially normal to and in contact with the profile of the peripheral form during or throughout a forming or like operation on the latter by the tool.

In order to ensure a robust and stable arrangement the said end part or head of the shaft is preferably closely adjacent to or against the bearing support structure.

The said end part or head of the shaft may carry a radially directed forming or like tool consisting of a holder having a diamond or like tip, or more than one such tool, and/or a rotary disc diamond tool having a multiplicity of diamonds or diamond particles set around its periphery.

In practical examples of an articulated diamond tool arrangement according to the invention reference is made to the further accompanying drawings in which: Figure 1 is an axial view of the arrangement showing the path of travel of the diamond tool about and in contact with a grinding wheel peripheral form; Figure 2 is a side elevation; Figure 3 is a detail view showing radial distance measurement; Figures 4 and5 each show a method of probe measurement of radial distance; Figures 6 and7 are respectively a side elevation and an axial view of a development of the arrangement and, Figures 8 and 9 are similar views of a further development.

Like or associated parts are referred to throughout all the drawings by the same or similar reference numerals.

Referring to Figures 1 and 2 a shaft 10 is journalled in a support bearing 12 and carries at its operative concentric end or head 11 a radially directed diamond tool 14, the cylindrical holder 140 of which is received in a radial bore or socket 114 in the head 11. The holder 140 protrudes from the head 11 for a suitable distance so as to present the diamond tip 144 to the peripheral form 150 of the grinding wheel 15 i.e. at a radial distance R from the axis OO of the shaft 10 and head 11.

This arrangement has the immediate advantage that it no longer requires the diamond tip 144 to be on the axis OO of the shaft 10 and entirely dispenses with the use of a swan neck arm.

As a result the arrangement can be much more robust and accurate particularly where, as shown, the head 11 is positioned closely adjacent to or against the bearing 12.

As will also be evident the arrangement is of compact form for convenient mounting of the support bearing 12 in position of use with little or no hindrance to the grinding area of a grinding machine. Furthermore the projection ofthe holder 140 and diamond tip 144 from the shaft head 11 provides adequate and unrestricted clearance for accommodating virtually any size or diameter of grinding wheel together with associated equipment such as a coolant nozzle 16 (or nozzles).

Referring again to Figure 1 the diamond tip 144 follows a part circular path about and against the rounded crest C of the profile of the grinding wheel form 150 and a straight line path along and against each of the flanks F. A corresponding path P of travel of the shaft 10 and bearing 12 at the radial distance R from the form 150 together with articulated or angular movement ofthe shaft 10 in the bearing 12 is effected to constantly present the diamond tip 144 at right angles, or substantially so, to the surface ofthe form 150 at all points around the latter and as the grinding wheel 15 rotates.

No articulation of the shaft 10 takes place when the diamond tip 144 rounds the crest C of the form 150 but articulation is necessary as the tip 144 proceeds along each flank F and as the support bearing 12 is fed towards the axis of rotation of the grinding wheel 15. The angle which the axis of the tip 144 and holder 140 assumes in relation to the direction of feed on such articulation is the angle of attack û.

Suitable feed mechanism such as coordinated screw operated slides respectively operating in linear directions towards the grinding wheel axis and also parallel with said axis effect required resultant movement of the diamond tip 144 along a flank F. The extent of the linear feed movement towards the grinding wheel axis is determined by the radial distance R times the cosine of the angle û and of the parallel movement by the distance R times the sine of the angle û.

Such operation of the feed mechanism and articulation of the shaft 10 can be readily carried out by suitable control means such as CNC control where the required form 150 is programmed in along with the known radial distance R. In fact CNC control can readily ensure that the diamond is presented "normal" to the profile of the form and in consequence diamond tip shape and/or radius become unimportant within practical limits. However some inclination of the tool from the direct radial direction may be adopted as necessary.

One method of measuring the radial distance R is shown in Figure 3 where the protrusion x of the diamond tip 144 from the periphery of the shaft head 11 is measured and also the diameter D of the head 11 (usually known). From such dimensions the radial distance R is simply determined as follows: R=D+x 2 In another method shown in Figure 4 a movable probe 19 is employed operating in conjunction with a CNC control. The spherical head 190 of the probe 19 is moved against the periphery of the shaft head 11 (of known diameter D) and then against the extremity of the diamond tip 144 to determine x. As before: R=D+x 2 By this method the probe 19 can be operated automatically from time to time for upgrading the dimension x and so take into account diamond tip wear.

In a development of the method shown in Figure 5 and where the diameter d of the probe head 190 is also known, the diamond tip 144 is first contacted at one side of the head 11, the latter rotated through 1800, and the tip again contacted at the other side so that the probe measures the distance Y. From this: R=Y- d 2 Here again protrusion x of the diamond tip 144 can be upgraded to allow for tip wear.

The robust construction of the articulated arrangement described above with reference to Figures 1 and 2 can be adapted and modified to carry a diamond disc 17 and/or one or more diamond tip holders 140.

Thus referring firstly to Figures 6 and 7 a rotary diamond disc 17 is carried at the end of the head 11 by a bracket 117 for rotation at right angles to the axis OO of the shaft 10. By articulation of the shaft 10 and feed of the support bearing 12 in the manner already described, the disc can be caused to follow the flanks F and crest C of the grinding wheel form 150 as indicated in Figure 7.

In Figure 6 the head 11 is also shown carrying a radially directed diamond tip holder 140 in the same manner as before for articulated presentation and operation either alternatively, or in conjunction with, the diamond disc 17.

In the development shown in Figures 8 and 9 a plurality of diamond tip holders 140 are carried by the head 11 e.g. in an equi-spaced arrangement such as the four holders 140 and tips 144 having their radial axes at right angles to one another. Each tip 144 can be brought into forming or dressing contact with the grinding wheel form 150 as and when required such as by means of a fixed slide stop. Once again a robust articulated forming arrangement is provided having a more versatile mode of operation.

It is to be understood that various other modifications may be made to the articulated diamond or like tool arrangement within the scope of the invention herein defined.

Claims (1)

1. An articulated diamond or like tool arrangement for forming, dressing or trueing a grinding wheel having a formed periphery is characterised by a shaft journalled in bearing support structure and which are together operable for movement along a path corresponding to and spaced from the profile of the peripheral form of the grinding wheel, a concentric end part or head of the shaft carrying at least one diamond or like tool for angular movement with the shaft whereby articulation of the tool so provided enables it to be presented substantially normal to and in contact with the profile of the peripheral form during or throughout a forming or like operation on the latter by the tool.