GB2214861A

GB2214861A - Routing bit

Info

Publication number: GB2214861A
Application number: GB8802725A
Authority: GB
Inventors: Robert Henry Williams; Jean Marie Gray
Original assignee: ROTO RAKE MANUFACTURING Ltd
Current assignee: ROTO RAKE MANUFACTURING Ltd
Priority date: 1988-02-06
Filing date: 1988-02-06
Publication date: 1989-09-13
Also published as: GB8802725D0

Abstract

A routing bit for attachment to a rotation means such as a hammer drill comprises a cylindrical shaft (10), a hexagonal shank portion (12) and a screw-thread portion (14). A plurality of cutting or abrasive members (18) in the form of generally rectangular cutting or abrasive material is provided at one end of the shank (10), and each is pressed into a respective longitudinally-extending slot (16) provided in the shaft (10). The cutting or abrasive members (18) are toothed, notched, crenulated or undulating, which makes more effective use of, for example, a reciprocating motion imparted to the bit by a hammer drill when removing mortar from joints between bricks. <IMAGE>

Description

DESCRIPTION ROUTING BIT The present invention relates to routing bits, and in particular, but not exclusively, to routing bits for releasable connection to a hammer drill.

Before pointing brickwork (i.e. replacing mortar which has become unsound) it is first of all necessary to remove loose and damaged mortar from between the bricks, otherwise fresh mortar will adhere to unsound mortar and this will shorten the life of the fresh mortar.

One way of removing unsound mortar is to use a hammer drill to which a routing bit is releasably connected. The combination of the rotational and reciprocal movement of the routing head induced by the hammer drill removes the loose mortar. A router for attachment to a hammer drill is described in co-pending United Kingdom Patent Application No.

86 25299.

It is an object of the present invention to provide a routing bit which removes unsound mortar more effectively, thereby improving the efficiency of the removal of mortar.

In accordance with the present invention, a routing bit comprises a shaft for releasable connection to a rotation means, and a plurality of cutting or abrasive members extending from the shaft, the cutting or abrasive members being toothed, notched, crenulated or undulating.

A routing bit with such cutting or abrasive members makes more effective use of the reciprical motion imparted by a hammer drill, thus resitting in more rapid renovl of mortar.

In a preferred embodiment, the routing bit comprises a plurality of cutting members projecting radially outwardly of the shaft. In one embodiment, the cutting members may be in the form of inserts which are pressed into longitudinally-extending grooves in the shaft. The inserts may be held in the grooves by additional fixing means, such as, for example, welding or brazing.

The present invention also provides a routing bit comprising a shaft adapted to be releasably connectable to rotation means, a plurality of slots in the shaft extending substantially parallel to the longitudinal axis of the shaft, and a respective cutting or abrasive member secured in each of the slots and projecting beyond the shaft, the cutting or abrasive members being toothed, notched, crenulated or undulating.

The invention also includes a routing bit as previously mentioned when fitted to a rotation means.

In particular, the invention includes such a routing bit when fitted to a drill, or to some other rotation means, such as that described in co-pending U.K. Patent Application No. 86 25299.

By way of example only, a specific embodiment of the present invention will now be described, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of an embodiment of routing bit in accordance with the present invention; Fig. 2 is a view in the direction of arrows II-II in Fig. 1; Fig. 3 is a side elevation of one of the cutting inserts of Fig. 1; Fig. 4 is a view in the direction of arrow IU of Fig. 3; and Fig. 5 is an end view of the cutting insert of Fig. 3, looking in the direction of arrow V.

The routing bit comprises a cylindrical shaft 10, a hexagonal shank portion 12 and a screw thread portion 14. By using a spanner on the hexagonal shank portion 12, the screw thread portion 14 may be screwed into the head of a hammer drill (not illustrated) or into some other rotatable device, such as described in co-pending application No.

86 25299, thereby releasably securing the router bit to the hammer drill or other device.

The cylindrical portion 10 is provided with three longitudinal slits 16, equally angularly spaced around the circumference of the cylindrical portion and extending parallel to the longitudinal axis thereof, and each of which is about two thirds of the length of the cylindrical portion 10. Each slit 16 is provided with a cutting insert 18, illustrated in more detail in Figs. 3 to 5.

Each cutting insert comprises an elongate, generally rectangular portion of tungsten carbide or other cutting or abrasive material. The upper edge 20 of each insert is provided with three arcuate recesses 22 which leave upstanding teeth portions 24 therebetween. A continuous cutting edge of four straight portions and three curved portions is thereby formed along the top edge 20 of each insert 18. As best seen in Fig. 5, the two lower edges 26,28 of each insert are chamfered to aid the insertion of the inserts into the corresponding slits 16 in the cylindrical portion of the router bit.

It can also be seen that the leading corner 30 of each insert is mitred and that the upper surface of each cutting insert is sloped (Fig. 5).

In use, each insert 18 is pressed into its respective slit 16, thereby securely attaching the inserts to the cylindrical portion 10. It can be seen in Fig. 1 that the ends of the cutting inserts project approximately 2mm beyond the free end of the cylindrical portion 10. It may also be necessary, or desirable, to secure the cutting inserts additionally, by, for example, welding or brazing the inserts into the respective slits 16. The routing bit is then ready for securing to a hammer drill by screwing the threaded portion 14 into a complementarily threaded receiving portion (not illustrated) in the hammer drill. This is aided by the provision of the hexagonal shank portion 12 which permits the use of a spanner.

The use of toothed, recessed, crenulated or other like undulating form for the cutting insert enables the routing bit to remove mortar more efficiently, since full use is made of the reciprocating motion imparted to the routing bit by the hammer drill.

It should be appreciated that the invention is not restricted to a router bit having a plurality of cutting members with recessed portions, but is equally applicable to such a routing head whose cutting members are provided with projections, which would, of course, define recesses therebetween.

The invention is not restricted to the details of the foregoing embodiment.

Claims

1. A routing bit comprising a shaft for releasable connection to a rotation means, and a plurality of cutting or abrasive members extending from the shaft, the cutting or abrasive members being toothed, notched, crenulated or undulating.

2. A routing bit as claimed in claim 1, comprising a plurality of cutting or abrasive members projecting radially outwardly of the shaft.

3. A routing bit as claimed in claim 1 or claim 2, wherein the cutting or abrasive members comprise inserts located in longitudinally-extending grooves in the shaft.

4. A routing bit as claimed in claim 3, wherein the inserts are pressed into the longitudinallyextending grooves.

5. A routing bit as claimed in claim 3 or claim 4, comprising additional fixing means.

6. A routing bit as claimed in claim 5, wherein the additional fixing means comprises welding or brazing.

7. A routing bit as claimed in any of claims 1 to 6, comprising means for releasably securing the bit to rotating means.

8. A routing bit as claimed in claim 7, comprising a screw-threaded portion.

9. A routing bit comprising a shaft adapted to be releasably connectible to rotation means, a plurality of slots in the shaft extending substantially parallel to the longitudinal axis of the shaft, and a respective cutting or abrasive member secured in each of the slots and projecting beyond the shaft, the cutting or abrasive members being toothed, notched, crenulated or undulating.

10. A routing bit as claimed in claim 9, wherein the cutting or abrasive members are pressed into their respective slots.

11. A routing bit as claimed in claim 10, comprising additional fixing means.

12. A routing bit as claimed in claim 11, wherein the additional fixing means comprises welding or brazing.

13. A routing bit as claimed in any of claims 10 to 12, comprising a screw-threaded portion for releasable connection to rotation means.

14. A routing bit as claimed in any of the preceding claims, wherein the cutting or abrasive members are generally rectangular.

15. A routing bit as claimed in claim 14, wherein the cutting or abrasive members are provided with a mitred corner.

16. A routing bit as claimed in any of the preceding claims, wherein the upper part cutting or abrasive surface of each cutting or abrasive member is sloped.

17. A routing bit substantially as herein described, with reference to, and as illustrated in, the accompanying drawings.

18. A rotation means when fitted with a routing bit as claimed in any of the preceding claims.