GB2301789A - A method and apparatus for brazing a tool blank onto a shank - Google Patents

Abstract

Apparatus (1) for brazing a tool blank (2) to a shank (3) in concentric alignment comprises an indexing table (15) which is movable through six work stations (17). Six carriers (18) are located on the indexing table (15) for carrying an assembled tool blank (2), shank (3) and brazing medium (6) through the work stations (17). In the first work station (17a) a shank (3), a brazing medium (6) and tool blank (2) are assembled in the carrier (18). The indexing table indexes each carrier (18) through three second work stations (17b) where gas torches (19) raise the temperature of a joint (7) and the brazing medium (6) above a fusing temperature. The carriers (18) are then indexed into a third work station (17c) where an alignment mechanism (21) aligns the tool blank (2) and shank (3) prior to fusing and clamps the tool blank (2) and shank (3) together until fusing has taken place.

Description

"A method and apparatus for brazing a tool blank onto a shank" The present invention relates to a method and apparatus for brazing a tool blank onto a shank so that the tool blank and shank are substantially concentric, and further, the invention provides a tool blank and shank concentrically brazed together using the apparatus and method according to the invention.

In general, tool blanks, for example, blanks for cutting tools, grinding tools and the like are of a relatively hardened steel, and in many cases, are of tungsten carbide steel. Because of the relatively high cost of such steels and the fact that being hard they are relatively difficult to work, in general, only the working portion of a tool is manufactured from these materials. In general, the working portion, which is generally referred to as the tool blank is mounted on a shank which is engaged in the chuck of a machine tool.

The shank, in general, is of mild steel or other relatively low cost and easily worked metal. The steel used in the tool blanks, in general, is unsuitable for welding, and generally, it is necessary to braze the tool blank onto the shank. It will be appreciated that since most cutting and grinding tools operate by being rotated, it is essential that the shank and tool blank should be substantially concentric prior to machining of the tool blank, and in general, it is necessary for both to be concentric to within 0.2 mm. This, in general, can be difficult to achieve.

There is therefore a need for a method and apparatus for enabling a tool blank to be brazed onto a shank so that the tool blank and shank are substantially concentric.

The present invention is directed towards providing such a method and apparatus, and the invention also provides a brazed tool blank and shank manufactured according to the method and apparatus.

According to the invention there is provided apparatus for brazing a tool blank onto a shank so that the tool blank and the shank are substantially concentric, the apparatus comprising a main framework, and an indexing table movably mounted on the main framework and indexable through a plurality of work stations, wherein at a first one of the work stations the shank and tool blank are assembled and clamped with a brazing medium between the tool blank and shank to the table, at a second one of the work stations heat is applied to the assembly of the tool blank and shank and the brazing medium for heating the brazing medium joint between the tool blank and the shank, and at a third one of the work stations the tool blank and the shank are concentrically aligned with each other while the joint is hot and the brazing medium is molten, and the tool blank and the shank are maintained concentrically aligned in the third work station until the joint has fused, a plurality of carriers mounted on the indexing table for carrying the assembled tool blank and shank from work station to work station, each carrier comprising a carrier housing mounted on the indexing table, and a collet located in a bore in the carrier housing for securing the shank in the bore of the carrier housing so that the shank extends from the carrier housing in a generally upwardly direction for receiving the tool blank, the collet being movable axially in the bore in the carrier housing for releasing and clamping the shank in the carrier housing, a retaining means for lightly engaging the tool blank when supported on the shank for retaining the tool blank and the shank together, the retaining means being mounted on the indexing table and being movable from a disengaged position disengaged from the tool blank to an engaged position engaging the tool blank, an operating means for axially moving the collet in the bore of the carrier housing for releasing the shank therefrom, the operating means being mounted on the main framework and being located at the first work station, a locating spindle mounted in the carrier housing and extending into the collet for engaging a lower end of the shank within the collet and for locating the shank therein, and an engagement pin extending from and resiliently mounted in the locating spindle for engaging and locating the shank in the collet, the engagement pin being resiliently movable axially in the locating spindle for permitting limited axial movement of the shank in the collet as the collet is being axially moved in the bore of the carrier housing for clamping the shank therein.

The advantages of the invention are many. However, by virtue of the fact that the engagement pin which engages the shank and extends from the locating spindle is resiliently mounted in the locating spindle, limited axial movement of the shank in the collet is permitted while the collet is axially moving for clamping the shank. This limited axial movement minimises the risk of concentric misalignment of the shank in the collet.

Indeed, it has been found that in virtually all cases, the shank is concentrically aligned with the collet when clamped therein.

Preferably, the locating spindle is adjustably mounted in the carrier housing for permitting the length to which the locating spindle extends into the collet to be adjusted for accommodating shanks of different length.

Advantageously, the collet is carried on a mounting member, the mounting member being spring urged relative to the carrier housing for urging the collet into a clamping position with the shank clamped therein.

Ideally, the operating means is engagable with the mounting member for moving the mounting member against the spring urging for axially moving the collet in the carrier housing for releasing the shank. Preferably, the operating means comprises an operating ram.

In one aspect of the invention a release means is located at the third work station for moving the retaining means to the disengaged position, and a subframework is located at the third work station for slidably carrying an alignment means which is slidable axially into engagement with the tool blank for locating the tool blank substantially concentrically aligned with the shank prior to fusing of the tool blank and the shank. Preferably, an alignment recess is provided in the alignment means, the alignment recess being engagable with the tool blank, the alignment recess being in concentric alignment with the collet in the carrier housings as each carrier is located in the third work station.

In one aspect of the invention a chuck is provided in the sub-framework for engaging and retaining the tool blank in axial alignment with the shank after the tool blank has been aligned with the shank by the alignment means.

Additionally, the invention provides a method for brazing a tool blank onto a shank so that the tool blank and shank are substantially concentric using the apparatus according to the invention, the method comprising the steps of moving the collet in the carrier housing for receiving the shank, inserting the shank into the collet, moving the collet in the carrier housing for clamping the shank in the carrier housing, placing the tool blank on the shank in reasonable alignment therewith with a brazing medium located between the tool blank and the shank, moving the retaining means into the engaged position for lightly engaging the tool blank for retaining the assembled tool blank and shank together, indexing the indexing table for moving the carrier from the first work station to the second work station for applying heat to the joint and the brazing medium between the tool blank and the shank, on the brazing medium being molten and the joint between the tool blank and the shank being heated and ready for fusing indexing the indexing table for moving the carrier from the second work station to the third work station, urging the alignment means into engagement with the tool blank for concentrically aligning the tool blank with the shank prior to fusing and operating the chuck in the sub-framework for retaining the tool blank in axial alignment with the shank until the tool blank and shank have fused together.

Preferably, the indexing table is indexed for moving the carrier from the third work station to the first work station, the collet being moved in the carrier housing for releasing the shank, and removing the fused tool blank and shank.

Further the invention provides a tool blank and a shank brazed together using the apparatus according to the invention with the tool blank and shank concentrically brazed together.

The invention also provides a tool blank and a shank brazed together using the method according to the invention with the tool blank and shank concentrically brazed together.

The invention further provides a tool blank and a shank brazed together using the method and apparatus according to the invention with the tool blank and shank concentrically brazed together.

The invention will be more clearly understood from the following description of a preferred embodiment thereof which is given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is an elevational view of a tool blank and shank according to the invention which have been brazed together using an apparatus and method according to the invention, Fig. 2 is an elevational view of apparatus according to the invention for brazing the tool blank and shank of Fig. 1, Fig. 3 is a plan view of the apparatus of Fig. 2, Fig. 4 is a sectional elevational view of a portion of the apparatus of Fig. 2 on the line IV IV of Fig. 3, Fig. 5 is a sectional elevational view of the portion of Fig. 4 of the apparatus of Fig. 2 on the line V-V of Fig. 3, Fig. 6 is a plan view on the line VI-VI of Fig. 4 of a detail of the portion of Fig. 4, Fig. 7 is a partly cross-sectional elevational view of a detail of the portion of Fig. 4 of the apparatus of Fig. 2, Fig. 8 is a plan view of the detail of Fig. 7 in the direction of the arrow VIII, Fig. 9 is a cross-sectional elevational view of another portion of the apparatus of Fig. 2, on the line IX-IX of Fig. 3, Fig. 10 is a cross-sectional plan view of a detail of the portion of Fig. 9 of the apparatus of Fig.

2 on the line X-X of Fig. 9, Fig. 11 is a plane view of another portion of the apparatus of Fig. 2, and Fig. 12 is an elevational view of the portion of Fig. 11 of the apparatus of Fig. 2 in the direction of the arrow XII of Fig. 11.

Referring to the drawings there is illustrated apparatus according to the invention indicated generally by the reference numeral 1 for brazing a tool blank 2 of tungsten carbide onto a shank 3 of mild steel of a grinding tool blank 4. In this embodiment of the invention the grinding tool blank 4 is ready for machining to form a grinding tool (not shown) for removing burs, and is typically referred to as a deburring tool. Such grinding tools and the method of forming a cutting surface onto the tool blank 2 will be well known to those skilled in the art, and since the forming of the cutting surface on the grinding tool blank 4 does not form part of the invention, no further descriptions of the machining of the surface of the tool blank 2 will be given. The tool blank 2 is of circular cross-section and tapers towards a tip 5.The shank 3 is of constant circular transverse crosssection, and is concentrically brazed to the tool blank 2. It is essential that the tool blank 2 and shank 3 should be concentric to within 0.2 mm of off-set. A brazing medium 6 is located between the joint 7 between the tool blank 2 and shank 3 for brazing the blank 2 and shank 3 together.

Returning now to the apparatus 1, the apparatus 1 comprises a main framework 10 having an upstanding pedestal 11 and a transversely extending frame 12 which extends outwardly of and around the pedestal 3. An indexing table 15 is carried on a main support housing 16 which is rotatably mounted in the direction of the arrow A in the pedestal 11 about a vertical axis for indexing the table 15 through a plurality of work stations through which assembled tool blanks 2 and shanks 3 which are carried on the indexing table 15 pass for brazing the tool blank 2 and shank 3 concentrically together. Six carriers 18 are rigidly mounted on the indexing table 15, and are equi-spaced at 600 intervals circumferentially around the indexing table 15 for carrying the tool blanks 2 and shanks 3 sequentially through the respective work stations 17.

In this embodiment of the invention six work stations 17 are provided, a first work station 17a is provided for loading shanks 3 into the respective carriers 18 and assembling the tool blank 2 onto the shank 3 with the brazing medium 6 located in the joint 7 between the blank 2 and shank 3. Three second work stations 17b are provided around the frame 12, and at each second work station 17b a gas torch 19 is located and mounted on the frame 12 for directing a flame onto the joint 7 between the tool blank 2 and the shank 3 and also onto the brazing medium 6 for heating the joint 7 and for raising the temperature of the brazing medium 6 to a temperature at which it becomes molten.Each of the second work stations 17b apply sufficient heat to the joint 7 and the brazing medium 6 so that by the time each carrier 18 is leaving the last of the three second work stations 17b, the joint 7 is at a temperature ready for fusing and the brazing medium 6 is molten. A third work station 17c is located after the third of the second work stations 17b, at which a sub-framework 20 is mounted on the frame 12 and carries an alignment mechanism which will be described below with reference to Fig. 9 for concentrically aligning the tool blank 2 with the shank 3 prior to fusing of the tool blank 2 and the shank 3. A fourth work station 17d located after the third work station 17c is provided with a blower mechanism (not shown) for blowing cold air at the tool blank 2 and shank 3 for cooling the tool blank 2 and shank 3 prior to being removed from the carrier 18.

Turning now to the carriers 18, and referring in particular to Figs. 4 to 8, each carrier 18 comprises a carrier housing 25 of steel which is secured to the indexing table 15 by three screws 26. A central bore 27 extending through each carrier housing 25 slidably carries a collet 28 for securely retaining and clamping a shank 3 therein. The collet 28 of each carrier 18 is carried on a mounting member 29 which is located in a chamber 30 within the carrier housing 25. The collets 28 are threaded at 31 and engage correspondingly threaded bores 32 through the respective mounting members 29. A closure plate 34 located within the carrier housing 25 closes the chamber 30 for retaining the mounting member 29 therein. Three screws 35 secure the closure plates 34 in the respective carrier housings 25.Four compression springs 37 located within the chamber 30 act between the carrier housing 25 and the mounting member 29 for urging the mounting member 29, and in turn, the collet 28 downwardly for clamping a shank 3 within the collet 28.

Each collet 28 is tapered at 38 and downward axial movement of the collet 28 in the bore 27 causes the tapered portion 38 of the collet 28 to co-operate with a correspondingly tapered portion 39 of the bore 27 for causing the collet 28 to clamp the shank 3 within the carrier housing 25. Two abutment pins 40 secured to and extending from each mounting member 29 extend through corresponding bores 41 in the closure plate 34 of each carrier housing 25. An operating means provided by an operating pneumatic ram 42, which is mounted on the frame 12 adjacent the first work station 17a beneath the indexing table 15 carries a thrust ring 43 for engaging the abutment pins 40 for urging the mounting member 29 upwardly against the spring urging action of the compression springs 37.The upward movement of the mounting member 29 causes the collet 28 to move axially upwardly in the bore 27 for releasing the shank 3 for facilitating placement and removal of a shank 3 in and from the collet 28. An opening 44 in the indexing table 15 beneath each carrier 18 accommodates the thrust ring 43 of the ram 42 as the respective carriers 18 are located in the first work station 17a. A foot pedal 24 at the base of the pedestal 11 is operable by an operator working at the first work station 17a for operating the ram 42.

A locating spindle 36 is mounted in the closure plate 34 of each carrier housing 25 and extends into the collet 28 for locating the shank 3 axially in the collet 28. The locating spindles 36 are axially threaded at 47 and engage respective threaded bores 51 in the closure plates 34 for facilitating adjustment of the distance the locating spindles 36 extends into the respective collets 28. Each locating spindle 36 is accessible from beneath the indexing table 15 through the opening 44 for adjustment thereof. An engagement pin 54 extends axially outwardly from each locating spindle 36 for engaging the shank 3.A compression spring 58 which acts between the engagement pin 54 and the locating spindle 36 resilient biases each engagement pin 58 axially outwardly of the corresponding locating spindle 36 for permitting limited axial movement of the shank 3 in the collet 28 as the collet 28 is being axially moved downwardly in the bore 27 in the carrier housing 25 during clamping of the shank 3 in the carrier housing 25. This limited downward movement of the shank 3 which is accommodated by the engagement pin 58 avoids any danger of the shank 3 being misaligned in the carrier housing 25 during clamping therein by the collet 28. A head 59 on each engagement pin 58 retains the engagement pins 58 within the corresponding locating spindle 36.

Centralising rings 55 are secured to the indexing table 15 and extend around the respective carrier housings 25 for centralising and aligning the carrier housings 25 on the indexing table 1S with the alignment mechanism 21, which is located at the third work station 17c as will be described below. Screws 56 secure each centralising ring 55 to the indexing table 15. Four adjusting grub screws 57 are equi-spaced at 900 intervals around each centralising ring 55 for engaging the corresponding carrier housing 25. A small clearance is provided between the respective carrier housings 25 and the screws 26 which secure the carrier housing 25 to the indexing table 15 for accommodating lateral movement of the respective carrier housings 25 within their corresponding centralising rings 55.

Accordingly, the position of each carrier housing 25 may be adjusted by the grub screws 57 in the centralising rings 55. The grub screws 57 also facilitate in retaining the carrier housings 25 in the respective aligned positions. On each carrier housing 25 being located in the desired aligned position, the screws 26 are then tightened, thereby further securing the carrier housings 25 to the indexing table 15.

A retaining means for lightly engaging the tool blank 2 for retaining the tool blank 2 assembled to a shank 3 with the brazing medium 6 located in the joint 7 between the tool blank 2 and the shank 3 comprises a retaining member 45 which is pivotally mounted on a mounting block 46 adjacent each carrier housing 25.

Each retaining member 45 comprises a retaining arm 48 which is carried on a carrier arm 49. The carrier arms 49 extend radially from respective pivot shafts 50 which are pivotally carried in the mounting blocks 46.

A nob 52 on each pivot shaft 50 is provided for pivoting the pivot shaft 50 and in turn the retaining arm 48 between an engaged position illustrated in Fig.

4 with the retaining arm 48 lightly engaging the tool blank 2 and a disengaged position illustrated in Fig. 5 disengaged from the tool blank 2. A counterweight 53 extends from the pivot shaft 50 for retaining the retaining arm 48 in either the engaged or disengaged positions. The position of the retaining arm 48 along the carrier arm 49 is adjustable for accommodating shanks 3 and tool blanks 2 of differing lengths.

The gas torches 19 at the three second stations 17b are conventional gas torches which direct a jet of gas/air mixture for flaming the joints 7, and accordingly, a further description of the gas torches 19 will not be given here.

Turning now to the third work station 17c, the aligning mechanism 21 which is housed in the sub-framework 20 will now be described with reference to Figs. 2, 3, 9 and 10. A support member 60 mounted on and extending upwardly from the frame 12 carries the sub-framework 20. The sub-framework 20 comprises a pair of spaced apart plate members 61 which are secured together by four tie bars 63 which clamp the plate member 61 onto a transverse member 65 extending sidewardly from the support member 60 towards the centre of and above the indexing table 15. A chuck 67 for engaging the tool blank 2 when aligned with the shank 3 is carried on a shaft 68 which is slidable vertically through a linear bearing 69 located in the plate members 61 and the transverse member 65.In this embodiment of the invention the chuck 67 is an eight jaw chuck having eight jaws 70 which engage around the outer periphery of the tool blank 2. A means for moving the chuck 67 downwardly into engagement with the tool blank 2 which is carried in a carrier 18 within the third work station 17c comprises a pneumatic ram 71 which is carried on a carrier framework 72. The carrier framework 72 is secured to and extends upwardly from the transverse member 65. Four guide rods 73 extending upwardly from a carrier plate 74 which is secured to the chuck 67 extend through linear bearings 75 in the plate members 61 for guiding the movement of the chuck 67 and the shaft 68 so that the chuck 67 slides axially upwardly and downwardly relative to a central axis 76 defined by the bores 27 of the carrier housing 25 when each carrier 18 is in the third work station 17c.

The alignment mechanism 21 comprises an alignment means for aligning the tool blank 2 with the shank 3 prior to engagement of the tool blank 2 in the chuck 67, and the alignment means comprises an alignment spindle 77 which is slidably mounted within the shaft 68 and also within the chuck 67 and is co-axial with the shaft 68 and the chuck 67. An alignment recess 78 is formed in the lower end of the alignment spindle 77 for engaging the tip 5 of the tool blank 2 for aligning the tool blank 2 with the shank 3.The alignment recess 78 is in concentric alignment with the axis 76 of the bore 27 of the carrier housing 25 when a carrier 18 is located in the third work station 17c, and the alignment recess 78 is so shaped as to urge the tool blank 2 into concentricity with the axis 76 extending through the bore 27 of the carrier housing 25, so that the tool blank 2 is in full concentric alignment with the shank 3. A compression spring 79 acting between the shaft 68 and the alignment spindle 77 resiliently mounts the alignment spindle 77 in the shaft 68 for facilitating further downward movement of the chuck 67 and shaft 68 after the alignment spindle 77 has come into engagement with the tool blank 2. A pin 80 extending through the alignment spindle 77 is engagable in a slot 81 extending transversely through the shaft 68 for retaining the alignment spindle 77 within the shaft 68.

A chuck operating means (not shown) for operating the chuck 67 for bringing the jaws 70 of the chuck 67 into engagement with the tool blank 2 after the tool blank 2 has been aligned with the shaft shank 3 by the alignment spindle 77 is provided but not illustrated.

Any suitable chuck operating means for operating such an eight jaw chuck which will be well known to those skilled in the art may be used.

Downward travel of the chuck 67 and shaft 68 is controlled by adjusting the screws 82 carried on an arm 84 extending transversely from the shaft 68.

A release means for pivoting the retaining member 45 into the disengaged position away from the tool blank 2 comprises a pneumatic ram 83 which is carried on an arm 84 extending from the support member 60. The ram 83 is operated as each carrier 18 has moved into the third station 17c for pivoting the retaining member 45 into the disengaged position for providing access to the tool blank 2 by the chuck 67 and the alignment spindle 77 for alignment of the tool blank 2 and the shank 3.

Referring now to Figs. 11 and 12, in order to counteract any back-lash in the indexing table 15, and for ensuring that each time the indexing table 15 stops, the carrier 18 which is located in the third work station 17c is properly aligned with the alignment mechanism 21, a locating member 85 is provided for taking up any back-lash that may exist in the indexing table 15. The locating member 85 is pivotally connected by a pivot pin 86 to the frame 12. A carrier arm 92 mounted on the frame 12 carries the pivot pin 86. A pneumatic ram 87 pivotally mounted on the carrier arm 92 by a pivot pin 93 pivots the locating member 85 about the pivot pin 86 for engagement with any one of six abutment dowels 88 extending downwardly from and beneath the indexing table 15.The action of the locating member 85 on the adjacent abutment dowel 88 after the indexing table 15 has indexed into an indexed position urges the indexing table in the direction of the arrow B and thus takes up any backlash which may be present in the indexing table 50, and thereby ensures accurate alignment of the alignment mechanism 21 with the carrier 18 which is located in the third work station 17c.

Referring now to Fig. 5, to avoid any danger of the action of the operating ram 42 on the abutment pins 40 causing distortion of the indexing table 15 a roller 89 rotatably carried on a roller carrier 90 is engagable with a track 91 mounted on the indexing table 15 adjacent each carrier housing 25. The roller carrier 90 is secured to the frame 12 adjacent the first station 17a.

In use, with the carrier housings 25 of each carrier 18 properly aligned with the alignment mechanism 21 of the third work station 17c the apparatus 1 is ready for use. Alignment of the carrier housings 25 with the alignment mechanism 21 is carried out by sequentially passing the carriers 18 through the third work station 17c, and when the indexing table 15 is in each indexed position and retained therein by the locating member 85, the carrier housing 25 is laterally adjusted within the centralising ring 55, as already described so that the axis 76 defined by the bore 27 through the carrier housing 25 is concentrically aligned with the alignment recess 78 in the alignment spindle 77.

Each time a carrier 18 passes through the first work station 17a a fused tool blank 2 and shaft 3 is removed from the carrier housing 2 and a new shank 3 is engaged in the collet 28 of the carrier housing 25. The brazing medium 6 is placed on top of the shank 3 and the tool blank 2 in rough alignment with the shank 3 is placed on top of the brazing medium. The retaining member 45 is pivoted by the nob 52 into the engaged position for lightly engaging the tip 5 of the tool blank 2 and retaining the assembly of the shank 3, the brazing medium 5 and the tool blank 2 in position. As the indexing table 15 indexes the carriers 18 in the direction of the arrow A through the three second work stations 17b the joint 7 between the tool blank 2 and shank 3 is heated for fusing and the brazing medium 6 is heated until it is molted. On each carrier 18 passing into the third work station 17c the ram 83 pivots the retaining member 45 into the disengaged position and the ram 71 urges the chuck 67 and alignment spindle 77 downwardly until the alignment recess 78 in the alignment spindle 77 engages the tip 5 of the tool blank 2 for concentrically aligning the tool blank 2 with the shank 3. On the tool blank 2 being aligned with the shank 3, the chuck 67 is operated so that the jaws 70 clamp onto the tool blank 2 thereby retaining the tool blank 2 in concentric alignment with shank 3. The tool blank 2 and shank 3 are retained in concentric alignment by the chuck 67 until the temperature of the tool blank 2, shank 3 and brazing medium 5 drop below the fusing temperature so that the tool blank 2 and shank 3 are fused together in concentric alignment.The jaws 70 of the chuck 67 are operated to disengage the tool blank 2 and the chuck 67 and alignment spindle 77 are raised by the ram 71 to clear the tool blank 2. The indexing table 15 then indexes to the next indexing position and the carrier 18 with the fused tool blank 2 and shank 3 is moved into the fourth work station 17d where the cooling air from the blower (not shown) cools the tool blank 2 and shank 3 prior to removal when the carrier 18 is moved again into the first station 17a.

It will be readily apparent to those skilled in the art that the apparatus and method may be used for brazing a tool blank of any type and shape to a shank of any type and shape with the tool blank and shank substantially concentrically aligned. It will also be appreciated that while it is desirable it is not essential that three second stations for heating the tool blank and shank may be provided. Indeed, in certain cases, it is envisaged that only one or two of the second work stations may be operational, where sufficient heat could be provided by two second work stations. In such cases, it is envisaged that the second work station nearest the third work station would normally be operational to minimise cooling of the tool blank and shank between the last of the three second work stations and the third work station.

Claims (16)

1. Apparatus for brazing a tool blank onto a shank so that the tool blank and the shank are substantially concentric, the apparatus comprising a main framework, and an indexing table movably mounted on the main framework and indexable through a plurality of work stations, wherein at a first one of the work stations the shank and tool blank are assembled and clamped with a brazing medium between the tool blank and shank to the table, at a second one of the work stations heat is applied to the assembly of the tool blank and shank and the brazing medium for heating the brazing medium joint between the tool blank and the shank, and at a third one of the work stations the tool blank and the shank are concentrically aligned with each other while the joint is hot and the brazing medium is molten, and the tool blank and the shank are maintained concentrically aligned in the third work station until the joint has fused, a plurality of carriers mounted on the indexing table for carrying the assembled tool blank and shank from work station to work station, each carrier comprising a carrier housing mounted on the indexing table, and a collet located in a bore in the carrier housing for securing the shank in the bore of the carrier housing so that the shank extends from the carrier housing in a generally upwardly direction for receiving the tool blank, the collet being movable axially in the bore in the carrier housing for releasing and clamping the shank in the carrier housing, a retaining means for lightly engaging the tool blank when supported on the shank for retaining the tool blank and the shank together, the retaining means being mounted on the indexing table and being movable from a disengaged position disengaged from the tool blank to an engaged position engaging the tool blank, an operating means for axially moving the collet in the bore of the carrier housing for releasing the shank therefrom, the operating means being mounted on the main framework and being located at the first work station, a locating spindle mounted in the carrier housing and extending into the collet for engaging a lower end of the shank within the collet and for locating the shank therein, and an engagement pin extending from and resiliently mounted in the locating spindle for engaging and locating the shank in the collet, the engagement pin being resiliently movable axially in the locating spindle for permitting limited axial movement of the shank in the collet as the collet is being axially moved in the bore of the carrier housing for clamping the shank therein.

2. Apparatus as claimed in Claim 1 in which the locating spindle is adjustably mounted in the carrier housing for permitting the length to which the locating spindle extends into the collet to be adjusted for accommodating shanks of different length.

3. Apparatus as claimed in Claim 1 or 2 in which the collet is carried on a mounting member, the mounting member being spring urged relative to the carrier housing for urging the collet into a clamping position with the shank clamped therein.

4. Apparatus as claimed in Claim 3 in which the operating means is engagable with the mounting member for moving the mounting member against the spring urging for axially moving the collet in the carrier housing for releasing the shank.

5. Apparatus as claimed in any preceding claim in which the operating means comprises an operating ram.

6. Apparatus as claimed in any preceding claim in which a release means is located at the third work station for moving the retaining means to the disengaged position, and a sub-framework is located at the third work station for slidably carrying an alignment means which is slidable axially into engagement with the tool blank for locating the tool blank substantially concentrically aligned with the shank prior to fusing of the tool blank and the shank.

7. Apparatus as claimed in Claim 6 in which an alignment recess is provided in the alignment means, the alignment recess being engagable with the tool blank, the alignment recess being in concentric alignment with the collet in the carrier housings as each carrier is located in the third work station.

8. Apparatus as claimed in Claim 6 or 7 in which a chuck is provided in the sub-framework for engaging and retaining the tool blank in axial alignment with the shank after the tool blank has been aligned with the shank by the alignment means.

9. Apparatus substantially as described herein with reference to and as illustrated in the accompanying drawings.

10. A method for brazing a tool blank onto a shank so that the tool blank and shank are substantially concentric using the apparatus as claimed in any preceding claim, the method comprising the steps of moving the collet in the carrier housing for receiving the shank, inserting the shank into the collet, moving the collet in the carrier housing for clamping the shank in the carrier housing, placing the tool blank on the shank in reasonable alignment therewith with a brazing medium located between the tool blank and the shank, moving the retaining means into the engaged position for lightly engaging the tool blank for retaining the assembled tool blank and shank together, indexing the indexing table for moving the carrier from the first work station to the second work station for applying heat to the joint and the brazing medium between the tool blank and the shank, on the brazing medium being molten and the joint between the tool blank and the shank being heated and ready for fusing indexing the indexing table for moving the carrier from the second work station to the third work station, urging the alignment means into engagement with the tool blank for concentrically aligning the tool blank with the shank prior to fusing and operating the chuck in the sub-framework for retaining the tool blank in axial alignment with the shank until the tool blank and shank have fused together.

11. A method as claimed in Claim 10 in which the indexing table is indexed for moving the carrier from the third work station to the first work station, the collet being moved in the carrier housing for releasing the shank, and removing the fused tool blank and shank.

12. A method for brazing a tool blank onto a shank, the method being substantially as described herein with reference to and as illustrated in the accompanying drawings.

13. A tool blank and shank brazed together using the apparatus as claimed in any of Claims 1 to 9 with the tool blank and shank concentrically brazed together.

14. A tool blank and shank brazed together using the method as claimed in any of Claims 10 to 12 with the tool blank and shank concentrically brazed together.

15. A tool blank and shank brazed together using the method as claimed in any of Claims 10 to 12 and the apparatus as claimed in any of Claims 1 to 9 with the tool blank and shank concentrically brazed together.

16. A tool blank and shank substantially as described herein with reference to and as illustrated in the accompanying drawings.