GB2211767A

GB2211767A - Method of and device for providing additional fixing locations on machine tables

Info

Publication number: GB2211767A
Application number: GB8723852A
Authority: GB
Inventors: Graham Nigel Clark
Original assignee: J A Clark & Co
Current assignee: J A Clark & Co
Priority date: 1987-10-10
Filing date: 1987-10-10
Publication date: 1989-07-12
Anticipated expiration: 2007-10-10
Also published as: GB2211767B; GB8723852D0

Abstract

For locating a workpiece and/or other item on a machine table typically of the kind having parallel inverted T-slots along the length of said table, an adaptor (10) of an H-shaped cross-section is formed with a longitudinally apertured crosspiece (14), and is located to the machine table by a conventional T-nut fixing so that the adaptor can extend transversely of the T-slots. The workplace is bolted to the adaptor(s) using T-nut fixings located underneath the crosspiece(s). The adaptor can have two in-line apertures in its crosspiece (14) or two parallel crosspieces. <IMAGE>

Description

Method of and Device for Providing Additional Fixing Locations on Machine Tables This invention relates to a method of providing additional fixing locations on a machine table and to a location adaptor for use in such method.

Typically, a machine table such as the table of a milling machine is provided with a series of parallel inverted-T slots running the length of the table. These slots are used to enable location and fixing of a workpiece and/or other item to the table, commonly by means of so called T-nuts located in the undercut region of the slot and tightened in position by a locking bolt, locking screw, screwthreaded locking pillar or the like which enables the fixing in position of a clamping plate or other clamping device or which in some instances forms part of such a clamping device.

Although the parallel inverted-T slots afford clamping sites for a workpiece or other item at any position along the length of the table, in the transverse, front-to-back direction clamping sites are restricted by the number of inverted-T slots provided in the table and by the spacing between them. The inability to fix a clamping device at any position in the transverse direction can prove disadvantageous, for example when small or irregularly shaped workpieces are to be located.

Moreover, machine tables are occasionally only provided with locating holes rather than inverted-T slots, and in this case the availability of clamping sites is even more restricted.

It is an object of this invention to provide a method of and device for locating a workpiece, tool or other item on a machine table, wherein disadvantageous restrictions on the positions of clamping sites are substantially avoided or at least minimised.

According to one aspect of the invention, there is provided a method of providing additional fixing locations for workpieces, clamps, fixtures or other items on a machine table according to which a location is effected through the intermediary of an adaptor which comprises a rigid elongate member which is generally of H-shaped transverse crosssection, apertured through its crosspiece over the major part of its length, and the said elongate member is located to the machine table by one or more conventional T-nut fixings and a workpiece, clamp, fixture and/or other item is fixed to the elongate member by one or more additional conventional T-nut fixings.

According to another aspect of the invention, there is provided a location adaptor for use in locating workpieces, clamps, fixtures and/or other items to a machine table by the aforesaid method, said adaptor comprising a rigid elongate member which is generally of H-shaped transverse cross-section, apertured through its crosspiece over the majority of its length.

The adaptor may be made of a metal such as steel or iron or of a lightweight alloy which affords rigidity with reduced weight or of a hard plastics material or of hard timber. In the case of a plastics or timber construction, the adaptor may be inexpensively produced for use a limited number of times before replacement.

The elongate member is preferably of symmetrical construction about median, longitudinally extending planes through its crosspiece, so as to present equal T-slots to view when seen from above and from below.

Further features of the method and device in accordance with the invention will be apparent from the following description, making reference to the accompanying drawings, in which: Figures 1 to 3 are respectively plan, side elevational and end elevational views of a location adaptor for use in the method in accordance with the invention; Figure 4 is an elevational view of a matching T-nut for use with the adaptor of Figures 1 to 3; Figures 5 and 6 show the assembly of the adaptor and T-nut with a locking bolt and with a clamp pillar respectively; Figures 7 and 8 are transverse cross-sectional views through the adaptor to show its method of use; and Figures 9 to 11 respectively show three possible modifications of the adaptor in somewhat diagrammatic manner.

Referring to Figures 1 to 3, the adaptor comprises a rigid elongate member 10, for example of suitable metal, alloy or hard plastics, generally of H-shaped transverse cross-section (Figure 3), and apertured at 12 through its crosspiece 14 over the entire length between two end regions 16. The adaptor presents equal T-slots 18, 20, to view, when seen from above and from below.

Figure 4 shows a matching T-nut with tongue or stem 16 and head 17.

Figure 5 shows the assembly of the adaptor 10 with a matching T-nut 26 and a matching fixing bolt 28, whilst Figure 6 shows the assembly of the adaptor 10 and T-nut 30 with a matching clamp pillar 32. Assembly is effected in this way in use, as illustrated in Figures 7 and 8.

Figure 7 shows the adaptor located and fixed in the inverted-T slot 22 of a machine table 24 by means of a conventional T-nut fixing, of which the T-nut is again referenced 26 and the locking bolt is referenced 28.

Figure 8 shows the manner in which the adaptor is utilised to locate and fix a workpiece or other item in position.

A conventional T-nut fixing, having T-nut 30 and a screwthreaded clamp pillar 32 is fixed to the adaptor. The clamp pillar 32 is utilised in a conventional manner to fix a clamping plate or like clamping device down on to the top of the workpiece or other item, thereby to clamp it relatively to the machine table via the adaptor fixing.

Clearly the additional T-nut fixing 30, 32 cannot be positioned at the same point along the length of the adaptor as the T-nut fixing 26, 28, but apart from this limitation, the clamping site for fixing 30, 32 may be anywhere along the adaptor length.

Moreover, the adaptor itself may be fixed to the machine table 24 at any point along the length of the inverted-T slot 22 in the table, and said adaptor may extend at any chosen angle or orientation relative to the length of said inverted-T slot.

In connection with the above-described adaptor, the following points should be understood: - the width of the through-slot or aperture > 12 (Figure 1) is sufficient for the slot to receive the tongue of the T-nut; - the width of the crosspiece 14, i.e. the width of the groove in the top of the H-shaped cross-section, is sufficient both to accept the width of the T-nut and provide sufficient clearance for a socket spanner to be used on the fixing bolt; and - the depth of the afore-mentioned groove above the crosspiece 14 is sufficient in use to accommodate the T-nut or the bolt head without protrusion thereof.

The adaptor therefore enables a clamping site for a workpiece, clamp, fixture, or other item to be located at almost any point in the area of the machine table, both in the longitudinal direction of the table and transversely thereto.

Clearly, if desired, the adaptor may be fixed to the machine table by more than one T-nut fixing 26, 28 and the workpiece or other item may be fixed to the adaptor by more than one T-nut fixing 30, 32. Moreover, more than one adaptor may be employed to provide suitable clamping sites for the workpiece or other item (such as an upstanding guide plate or stop plate) to be located to the table.

In many instances the workpiece or other item to be located will be disposed to the side of the adaptor or adaptors, so as to be clamped down into direct engagement with the machine table. In some instances, however, it may be desired to clamp the workpiece down on top of the adaptor, whereby the latter also serves the purpose of spacing the workpiece above the machine table, for example to provide free space beneath the workpiece enabling it to be worked right through to its undersurface.

It will also be appreciated that, in the case of a machine table having locating holes rather than inverted-T slots, the adaptor in accordance with the#invention affords much greater freedom for location of clamping sites both in the longitudinal direction and the transverse direction of the machine table. This may be especially advantageous in the case of a pressing machine, for example, in providing greater freedom for location of one of the press tools.

Figure 9 shows a modification of the adaptor 10 in which it is provided with a lateral extension 40 affording a laterally open T-slot 42. The T-slot 42 enables conventional T-nut fixings to be employed for the fixing in position of guide plates or stop plates, for example.

Figure 10 shows an adaptor 10A of increased length, wherein, in order to maintain rigidity, two elongate apertures 12A, 12B through the crosspiece are spaced by a central bridge 44.

Figure 11 shows a further modification in which the adaptor 10B comprises a double-H section, with dual apertured crosspieces 14A, 14B. If desired, one apertured crosspiece may be employed for fixing the adaptor to the machine table, and the other for fixing the workpiece or other item to the adaptor.

Obviously, the modifications of Figures 9 to 11 can be incorporated in the adaptor in combination, if desired.

Referring back to Figures 1 to 4, on which dimensions are indicated by reference letters, as an exemplary guide to approximate dimensions, the following table is applicable.

Differently sized machine tables will take differently sized adaptors, T-nuts, etc., and the dimensions given are for two typical cases. All dimensions are in millimetres.

T-nut sizes are designated conventionally.

T-Nut Size M6 x 8.0 M30 x 36.0 E 13 54 L1 180 800 L2 160 720 A 8 36 B 15 60 C 7 1 30 D 6 30 T 20 90 W 27 120 H 10 44 K 6 | 22 ~ M 6 ' 30 F 7.6 35.6 Various modifications of the above-described method and device are possible within the scope of the invention hereinbefore defined.

Claims

1. A method of providing additional fixing locations for workpieces, clamps, fixtures or other items on a machine table according to which a location is effected through the intermediary of an adaptor which comprises a rigid elongate member which is generally of H-shaped transverse crosssection, apertured through its crosspiece over the major part of its length, and the said elongate member is located to the machine table by one or more conventional T-nut fixings and a workpiece, clamp, fixture and/or other item is fixed to the elongate member by one or more additional conventional T-nut fixings.

2. A location adaptor for use in locating workpieces, clamps, fixtures and/or other items to a machine table by the method according to claim 1, said adaptor comprising a rigid elongate member which is generally of H-shaped transverse cross-section, apertured through its crosspiece over the majority of its length.

3. An adaptor according to claim 2, made of steel or iron or a rigid lightweight alloy.

4. An adaptor according to claim 2, made of timber or plastics material.

5. An adaptor according to claim 2 or claim 3 or claim 4, wherein the H-shaped cross-section is of symmetrical construction about median, longitudinally extending planes through the crosspiece of the elongate member, so as to present equal T-slots to view when seen from above and below.

6. An adaptor according to any of claims 2 to 5, in which the crosspiece is apertured at two or more longitudinally extending portions of the elongate member.

7. An adaptor according to any of claim 2 to 6, wherein the elongate member has a double-H cross-section, with coplanar apertured crosspieces.

8. An adaptor according to any of claims 2 to 7, wherein the elongate member has a lateral extension to the side of the H-shaped cross-section, the lateral extension having an undercut recess defining a laterally open I-slot.

9. A method of providing additional fixing locations for workpieces and/or other items on a machine table, substantially as hereinbefore described with reference to Figures 5 to 8 of the accompanying drawings.

10. A location adaptor for a machine table, substantially as hereinbefore described with reference to Figures 1 to 4 and Figures 9 to 11 of the accompanying drawings.

11. A machine table having a workpiece and/or other item located and secured in position thereon by the method of claim 1 or claim 9, using the adaptor of any one of claims 2 to 8 or claim 10.