Method for making drill-chuck jaw with hard-metal inserts

Abstract

A drill-chuck jaw is made by first forming an elongated metal body with a toothed back face and a planar front face and thereafter laser-welding an insert to the body on the face. After machining the body but before laser-welding the inserts to it, the body is heat-treated and surface hardened. After the heat-treating and surface-hardening step and before the laser-welding step, the body in tampered.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to drill-chuck jaw. More particularly this invention concern method making such a jaw equipped with one or more hard-metal inserts.

BACKGROUND OF THE INVENTION

[0002] A standard drill chuck has a body centered on and rotatable about an axis and formed with a plurality of axially extending angled guides angularly spaced about the axis. Respective jaws in these guides can be moved between a forward holding position in which they grip a workpiece and a rear releasing position. Teeth on back edges of the jaws mesh with a threaded ring that is rotated relative to the chuck body to advance and retract the jaws. Alternately the guides are formed in a sleeve that rotates relative to the chuck body and the teeth on the jaws mesh with a screwthread on the body for similar action.

[0003] Even though the jaws are made of steel, they are typically used to grip tools of similar hardness. Thus it is known to provide special hard-metal, e.g. carbide, inserts in the gripping faces of the jaw to reduce wear of the jaws and thereby prolong the life of the drill or lathe carrying the chuck.

[0004] Such inserts must be mounted very, very solidly on the chuck jaws. Once installed they must be able to withstand considerable lateral forces as the chuck applies torque to the tool, and they must hold even when the entire tool gets fairly hot as in common machining.

[0005] In commonly owned U.S. Pat. No. 6,427,555 we disclose such a jaw-making method comprising the steps of forming an elongated metal body with a toothed back face and a front face, machining a longitudinally extending groove having sides and a floor in the front face, forming on each of the groove sides a pair of inwardly projecting and longitudinally spaced bumps with the bumps on one of the groove sides transversely aligned with the bumps on the other of the groove sides, fitting into the groove between the pairs of retaining bumps a hard-metal insert, and bonding the insert to the body in the groove.

[0006] While this procedure produces a very strong jaw with a very solidly mounted insert, it is quite difficult and complex. Machining the groove and providing the holding bumps adds two steps to the manufacturing process. Furthermore once the insert is thus mounted it is standard to subject the entire jaw, with insert, to various heat-treating steps that in fact reduce the hardness of the insert and/or jaw. Furthermore the presence of solder or adhesive between the insert and the body face it is mounted to, normally the floor of the groove, requires that the insert be machined after attachment of the inserts to guarantee perfect positioning of the insert faces.

OBJECTS OF THE INVENTION

[0007] It is therefore an object of the present invention to provide an improved method of making a drill-chuck jaw.

[0008] Another object is the provision of such an improved method of making a drill-chuck jaw which overcomes the above-given disadvantages, that is which is relatively simple and which produces a very strong and hard jaw.

SUMMARY OF THE INVENTION

[0009] According to the invention a drill-chuck jaw is made by first forming an elongated metal body with a toothed back face and a planar front face and thereafter laser-welding an insert to the body on the face. More particularly, after machining the body but before laser-welding the inserts to it, the body is heat-treated and surface hardened.

[0010] Thus with this method it is normally only necessary to form a simple planar face on the jaw. This is a relatively easy procedure completed quickly and very accurately by milling. By not using solder or an adhesive between the insert and the face, positioning will be perfect so that no subsequent machining of the jaw will be necessary. What is more the laser welding operation is so accurate and quick that it introduces no meaningful stresses into the workpiece, so once the insert is lager-welded in place, the workpiece is finished.

[0011] According to the invention, after the heat-treating and surface-hardening step and before the laser-welding step, the body is tampered. Thus this step is also completed before the insert or inserts are laser-welded in place.

[0012] In accordance with another feature of the invention, before the heat-treating and surface-hardening step a longitudinally extending centering formation in formed on the face. Thereafter but before the laser-welding step, the insert is fitted to the formation.

BRIEF DESCRIPTION OF THE DRAWING

[0013] The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

[0014] FIGS. 1 and 2 are side views of a drill-chuck jaw according to the invention;

[0015] FIG. 3 is a section taken along line III-III of FIG. 2;

[0016] FIG. 4 is a side view of another jaw;

[0017] FIG. 5 is a section taken along line V-V of FIG. 4;

[0018] FIG. 6 is a side view of yet another jaw;

[0019] FIG. 7 is a section taken along line VII-VIl of FIG. 5;

[0020] FIGS. 8 and 9 are views like FIG. 7 of further chucks in accordance with the invention; and

[0021] FIG. 10 is a block diagram illustrating the method of this invention.

SPECIFIC DESCRIPTION

[0022] As seen in FIG. 1 through 3 and 10, a drill-chuck jaw 1 according to the invention is made by first machining a cylindrical steel body or pin so that one side has at one end a row of teeth 2 extending parallel to a center axis 4 of the pin, and then machining at the opposite end, and here on the opposite side, a planar face 3 extending at a small acute angle across the axis 4. Then the workpiece is heat treated to reduce internal stresses. Subsequently it is surface hardened.

[0023] Thereafter hard-metal inserts 5 are positioned on the face 3 and secured thereto by laser-welds 8. Thus the various treatments are all completed before these inserts 5 are installed. The laser-welding does not create any significant stresses in the steel of the jaw 1, so that once the inserts 5 are mounted, the jaw is complete.

[0024] FIGS. 4 and 5 show how the face 3 is formed with a central longitudinally extending rib 6 that is fitted to a groove 7 in the jaw 5a. The interfit of the formations 6 and 7 ensures perfect positionign of the inserts 5, making welding them easier.

[0025] In FIGS. 6 and 7 the face 3 is formed with a square-section rib 6b and the jaw 5b has a square-section groove 7b complementary to it. FIG. 8 shows a semicircular-section rib 6c and a complementary groove 7c.

[0026] In FIG. 9 the face is formed with a square-section groove 6d into which the entire insert 5 is set.

Claims

1. A method of making a drill-chuck jaw comprising the steps of sequentially; forming an elongated metal body with a toothed back face and a planar front face; and laser-welding an insert to the body on the face.

2. A method of making a drill-chuck jaw comprising the steps of sequentially: forming an elongated metal body with a toothed back face and a planar front face; heat-treating and surface hardening the body; and laser-welding an insert to the body on the face.

3. The jaw-making method defined in claim 2, further comprising after the heat-treating and surface-hardening step and before the laser-welding step the step of tampering the body.

4. The jaw-making method defined in claim 2, further comprising before the heat-treating and surface-hardening step the steps of forming a longitudinally extending centering formation on the face, and thereafter but before the laser-welding step; fitting the insert to the formation.