GB2344831A

GB2344831A - A method of manufacturing a tufting machine hook

Info

Publication number: GB2344831A
Application number: GB9823233A
Authority: GB
Inventors: Ian Beverley
Original assignee: COBBLE BLACKBURN Ltd
Current assignee: COBBLE BLACKBURN Ltd
Priority date: 1998-10-24
Filing date: 1998-10-24
Publication date: 2000-06-21
Also published as: GB9823233D0

Abstract

In a method of manufacturing an improved tufting hook in which separate hook and shank parts (30, 10) are held together and are then permanently secured together, for example by brazing, the hook part (30) and the shank part (10) comprise complementary formations, for example a mortice and a tenon to a form a dovetail type joint and shearable or deformable protrusions (21) may be provided on the formations which upon engagement are sheared or deformed to hold the hook (30) and shaft part (10) together in accurate alignment by frictional contact prior to the permanent securing operation.

Description

A METHOD OF MANUFACTURING AN IMPROVED TUFTING HOOK This invention relates to a method of manufacturing an improved tufting hook and more particularly to a method of manufacture of a tufting hook comprising at least two parts secured together. The invention also relates to an improved tufting hook formed by the method of the invention.

Tufting hooks are used in tufting machines for the production of tufted fabrics, for example carpets. Historically such hooks were formed in one piece from a material such as steel, however, latterly it has been found that the operative part of the hook is liable to excessive wear during use and, therefore, requires regular replacement. Accordingly it has now become customary to either form the operative part of the hook from a material which is less liable to wear or at least to provide an insert into the operative part of the hook of a material which has less liability to wear, thereby prolonging the working life of the hook. The material most commonly used to form the operative part of the hook, or the insert into the operative part of the hook, is tungsten carbide.

The present invention is concerne with the manufacture of tufting hooks where the operative part of the hook is formed as one part and the non-operative part of the hook is formed as a second part, the two parts being permanently attached together to form the finished tufting hook.

A problem arises in the manufacture of tufting hooks from separate parts attached together. The first problem which arises is that in conventional manufacturing methods, the operative and non-operative parts of the hook have to be held accurately in position, with a small gap therebetween, whilst the parts are secured together to ensure accurate alignment of the parts in the finished hook. It can be difficult to ensure that this happens in the manufacturing process and to achieve the required accuracy, necessitates the use of some form of holding device for each of the parts, necessarily increases the cost of the process.

Furthermore, because of the need for accurate alignment of the parts, the placement of the parts in a holding device and their accurate alignment can take some time and, therefore, can increase the time necessary to manufacture the tufting hooks according to the conventional process.

A second problem which arises is that, due to the nature and type of joint between the respective parts, the joint is susceptible to breakage when in use in a tufting machine.

It is accordingly an object of the present invention to provide a method of manufacture of a tufting hook, and an improved tufting hook, in which these problems are overcome or at least minimised.

Thus and in accordance with the first aspect of the present invention, therefore, there is provided a method of manufacturing a tufting hook comprising the steps of forming operative and non-operative parts of said hook respectively as separate parts, said operative and nonoperative parts having complementary engageable formations thereon, engaging the complementary formations on the operative and non operative parts together to attach the non-operative parts to the operative parts, the engaged complementary formations being capable of holding said parts together in accurate alignment and permanently securing said parts together to form a tufting hook.

With this method it is possible to manufacture a tufting hook in a simple a quick manner whilst ensuring the accuracy of alignment of the parts in the finished hook. Furthermore because of the use of complementary formations, which engage with each other and which are permanently secured together, the finished hook is less prone to breakage along the joint between the two parts.

Preferably the complementary formations are formed as respectively a mortice recess and a tenon projection on a respective one of the operative and non-operative parts. Most preferably the complementary formations are formed on respective ends of the operative and non-operative parts.

Preferably the mortice recess has at least one protrusion projecting from an inner surface thereof, which protrusion, upon engagement of the tenon projection with the mortice recess is deformed by, or at least partially sheared, whereby said deformed or partially sheared protrusion maintains engagement between the two parts by frictional contact with said mortice recess and an outer surface of said tenon projection. Most preferably multiple protrusions are provided spaced around the inner surface of the recess.

Preferably the operative and non-operative parts are permanently secured together by brazing. Alternatively any other forms of permanent securing can be used as desired or as appropriate.

The invention also provides an improved tufting hook comprising a non-operative shank part and an operative part permanently secured to each other, said operative and non-operative parts having complementary formations thereon which are engageable to hold said shank and hook parts together, prior to permanent securing.

Preferably the shank part is formed of a resilient metallic material most preferably comprising steel material. Preferably the hook part is formed of relatively hard wearing material such as a ceramic and most preferably is formed from tungsten carbide.

Preferably at least one of the formations is provided with at least one protrusion thereon which upon engagement of said formations is deformed or at least partially sheared and holds said formations together by frictional engagement therewith.

Preferably one of the complementary formations is formed as a mortice recess and the of the complementary formations is formed as a tenon projection whereby the connection between the shank and hook parts is of a type usually referred to as a"dovetail joint".

Most preferably the tenon projection extends from one end of the hook part and the mortice recess is disposed in one end of the shank part.

Preferably the tenon projection is generally L-shaped and forms essentially two substantially orthogonal arms, one arm of which is adapted to engage in the mortice recess and the other arm of which is adapted to be retained in position by a retaining lip provided on the shank part.

Most preferably, the mortice recess is provided with a pluraiity of protrusions therein spaced around the recess, all of which are adapted to be deformed or at least partially sheared upon engagement of the tenon projection with the recess. Still further at least one protrusion can be provided externally of said mortice recess and in a position such that said other arm of said tenon projection is capable of deforming or shearing said at least one portion of a protrusion upon engagement of the hook and shank parts together whereby said deformed or sheared protrusion assists in holding said other arm in position with the retaining lip by providing frictional contact therebetween.

An additional advantage of the use of shearable protrusions is that when the hook part and shank part are engaged together and held together securely by the frictional contact between the projection and the protrusions, a small gap suitable for brazing is provided between the complementary formations on the hook and shank and this provides a uniform gap into which the material used to permanently secure the hook and shank parts together can be introduced.

The invention will now be described further by way of example and with reference to the accompanying drawings of which: Fig. 1 shows a diagrammatic side view, not to scale, of one form of shank part according to the present invention; Fig. 2 shows a diagrammatic side view, not to scale, of one form of hook part according to the present invention, and Fig. 3 shows a diagrammatic side view, not to scale, of an assemble tufting hook formed from the hook and shank parts of Figs. 1 and 2.

Referring now to Fig. 1, there is shown one form of shank part 10 according to the present invention. The shank part 10 comprises a shank 11 of conventional form by which the tufting hook, once assemble, can be mounted directly onto the hook bar of a tufting machine or into a module, along with a number of similar hooks which is then attached to the hook bar of the machine. The other end of the shank part 10 is shaped so as to define a mortice recess 12, bearing surfaces 13,14 and a projecting retaining lip 16. Each of the bearing surfaces 13,14 and in each of the internal walls 17,18,19 of the mortice recess 12 is provided with at least one protrusion 21 therein.

Whilst in the embodiments described thus far, at least one protrusion 21 is provided on each of the bearing surfaces 13,14 and on the internal walls 17,18,19 of the mortice recess 12, it is not essential that all of the internal walls 17,18,19 of the mortice recess 12 and the bearing surfaces 13,14 have a protrusion 21 thereon. The only essential feature is that sufficient protrusions 21 are provided on the internal walls of the mortice recess 12 and the bearing surfaces 13,14 to provide sufficient frictional contact to hold the two parts of the hook together when the two parts are engaged in a manner to be described hereinafter.

Each protrusion 21 is formed as one piece with the remainder of the shank part 10.

Fig. 2 shows one form of hook part 30 according to the present invention. The hook part 30 comprises a tip and a generally L-shaped tenon projection 32 by which the hook part can be attached to the shank part 10. The tenon projection 32 comprises two substantially orthogonal arms 33,34. The hook part 30 is formed as one piece from a material which is hard wearing and preferably tungsten carbide is used.

In order to form the improved hook of the invention, as shown in Fig. 3 of the drawings, the tenon projection 32 on the hook part 30 is engaged with the mortice recess 12 and the retaining lip 16 of the shank part 10. In so doing, the protrusions 21 provided on the inner walls 17, 18,19 of the mortice recess and the bearing surfaces 13,14 are deformed or at least partially sheared by contact with the outer surfaces 36,37,38 of the tenon projection 32 such that deformed or sheared top surfaces of the protrusions 21 bear against the outer surface of the tenon projection 32 and provide frictional contact between the two parts 10, 30 of the hook. This frictional contact ensures that the shank part 10 and the hook part 30 are held securely together once the tenon projection 32 has been engaged with the mortice recess 12 and the retaining lip 16.

The deformed or partially sheared protrusions 21 also ensure that between the mortice recess 12 and the bearing surfaces 13,14, and the outer surface 36,37,38 of the tenon projection 32 there is a gap suitable for brazing. Once the hook part 30 and shank part 10 have been engaged, the parts can be permanently secured together by brazing or any other suitable form of permanent securing. The presence of the gap provided by the protrusions 21 assist in the securing of the two parts 10,30 together since it provides an area into which the brazing material can flow to provide a strong attachment. The presence of the protrusions 21 also ensures that the gap is substantially uniform in width along its length and renders the appearance of the finished hook more attractive.

It will be appreciated that a number of important advantages are obtained using the manufacturing method of the invention and further advantages are obtained in the finished hook. Firstly, the use of the deformable or shearable protrusion 21 means that during manufacturing it is not necessary for the hook and shank parts 10,30 to be held in position while they are being permanently secured using any external holding device. This is necessary in prior art methods since it is necessary to hold the pieces adjacent to each other, with a small gap therebetween, whereby the permanent securing can take place. The holding device is also necessary in prior art methods to ensure accurate and consistent alignment of the parts of the hook whilst they are being secured and, therefore, it can be quite time consuming to set the parts in the holding device in such accurate alignment. This difficulty is clearly obviated in the method of the present invention since the frictiona ! contact with the sheared protrusions keeps the hook and shank parts in the desired position relative to each other while permanent securing takes place. The lack of requirement for an external holding device clearly reduces the cost of the manufacturing process and also the time involved in carrying out the process as described above. In the finished hook, an important advantage is gained from the use of a"dovetail"type joint.

Such a joint imparts considerably greater strength to the finished hook because the joint between the two parts is less susceptible to breakage.

In the prior art hooks which are formed according to prior art methods, the ends of the hook part are simply held adjacent to each other with no engagement and are then secured by suitable permanent securing which will quite clearly lead to a much weaker joint between the two parts.

It is, of course, to be understood that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only.

Claims

CLAIMS 1. A method of manufacturing a tufting hook comprising the steps of forming operative and non-operative parts of said hook respectively as separate parts, said operative and non-operative parts having complementary engageable formations thereon, engaging the complementary formations on the operative and non operative parts together to attach the non-operative parts to the operative parts, the engaged complementary formations being capable of holding said parts together in accurate alignment and permanently securing said parts together to form a tufting hook.
2. A method according to Claim 1, wherein the complementary formations are formed as respectively a mortice recess and a tenon projection on a respective one of the operative and non-operative parts.
3. A method according to Claim 1 or Claim 2, wherein the complementary formations are formed on respective ends of the operative and non-operative parts.
4. A method according to Claim 2 or Claim 3, when dependent on Claim 2, wherein the mortice recess has at least one protrusion projecting from an inner surface thereof, which protrusion, upon engagement of the tenon projection with the mortice recess is detormed by, or at least partially sheared, whereby said deformed or pa,-tjally sheared protrusion maintains engagement between the two parts by frictional contact with said mortice recess and an outer surface of said tenon projection.
5. A method according to Claim 4, wherein multiple protrusions are provided spaced around the inner surface of the recess.
6. A method according to any one of Claims 1 to 5, wherein the operative and non-operative parts are permanently secured together by brazing.
7. An improved tufting hook comprising a non-operative shank part and an operative part permanently secured together, said operative and non-operative parts having complementary formations thereon which are engagement to hold said shank and hook parts together, prior to permanent securing.
8. An improved tufting hook according to Claim 7, wherein the shank part is formed of a resilient metallic material.
9. An improved tufting hook according to Claim 8, wherein the resilient metallic material comprises steel.
10. An improved tufting hook according to any one of Claims 7 to 13, wherein the hook part is formed of relatively hard wearing material.
11. An improved tufting hook according to Claim 10, wherein the hard wearing material comprises a ceramic material.
12. An irr. proved tufting hook according to Claim 10, wherein the hard wearing material comprises Tungsten carbide.
13. An improved tufting hook according to any one of Claims 7 to 13, wherein at least one of the formations is provided with at least one protrusion thereon which upon engagement of said formations is deformed or at least partially sheared and hold said formations together by frictional engagement therewith.
14. An improved tufting hook according to any one of Claims 7 to 13, wherein one of the complementary formations is formed as a mortice recess and the other of the complementary formations is formed as a tenon projection whereby the connection to the shank and hook parts is of the type usually referred to as a"dovetail joint".
15. An improved tufting hook according to Claim 14, wherein the tenon projection extends from one end of the hook part and the mortice recess is disposed in one end of the shank part.
16. An improved tufting hook according to Claim 14 or Claim 15, wherein the tenon projection is generally L-shaped and forms two essentially substantially orthogonal arms, one arm of which is adapted to engage in the mortice recess and the other arm of which is adapted to be retained in position by a retaining lip provided on the shank part.
17. An improved tufting hook according to any one of Claims 14 to 16, wherein the mortice recess is provided with a plurality of protrusions therein spaced around the recess, all of which are adapted to be deformed or at least partially sheared upon engagement of the tenon projection with the recess.
18. An improved tufting hook according to any one of Claims 7 to 17, wherein at least one protrusion is provided externally of the mortice recess and in a position such that said other arm of said tenon projection is capable of deforming or shearing said at least one portion of the protrusion upon engagement of the hook and shank parts together whereby said deformed or sheared protrusion assists in holding said other arm in position with the retaining lip by providing frictional contact therebetween.
19. A method according to Claim 1, substantially as hereinbefore described with reference to the drawings.
20. An improved tufting hook according to Claim 7, substantially as hereinbefore described with reference to the accompanying drawings.