FI124141B - A method of making a drill bit - Google Patents

Description

METHOD FOR MANUFACTURING RING BLADE

The invention relates to a method of producing a hollow drill device for producing a sleeve-like annular ring 5 for inserting and locking a central drill bit for drilling in the center of a hole; surfaces communicating with the ring blade 10 A drill device with a central blade and a ring blade of the type described above, e.g. Finnish Patent Publication FI-115661. In this solution, the annular blade is made of a blank by turning and the shapes of the hem are made by milling. After machining, the blade is hardened.

15 In the manufacturing method described above, the design of the skirt portion is limited by the ability of the machining process to produce sharp angles and small radii of curvature. When hardening is done on a finished workpiece, the impact surfaces of the skirt become hard on all sides and, consequently, they wear down the contact surfaces that make the center blade impact. No more than one hole is drilled, while the same center bit is used to make dozens of holes. Thus, the hard surface of the Ren-20 gaster blade does not require maximum hardness. As a result of the annealing of an asymmetrical mass center of the blade, deformation, such as an oval to the sleeve-like piece, easily occurs.

In the example of US 5,388,484, two ring blades are cut by laser cutting

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ς 25 offset from the center of each of the cylindrical preforms to give each blade a twist

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^ Thanks to the cutting line, the blade teeth. The central portion of the blank is a cylindrical portion of sintered blade material. The sintered cylindrical section is laser cut, whereby the o annular ring has sintered toothed teeth. The consumption of smelting matrix is exactly the same whether each blade is sintered in the mold individually or in combination with a release cut.

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To eliminate the above-described drawbacks, a new manufacturing method has been developed, characterized in that two ring blades are first made from one blank with a common hem portion, preferably to the final dimensions, and the resulting piece is separated into two annular blades by cutting the portion

The advantage of the method is the saving of raw materials and the saving of machining, which can be utilized even in a part that has already been turned from the blank. It is especially useful if the piece is made from a blank that is shaped by rolling close to the dimensions. The advantage of tempering is the symmetrical shape of the piece, which avoids the effect of mass concentrates on tempering. When the blades are separated from the body by a shape cut, e.g., a laser cut, a release effect is produced on the cutting surface, which reduces the hardness of the surface. A reduction in the hardness of the counter surface is even desirable in the annular blade and has the advantage of extending the life of the central blade. Separation cutting by laser cutting or the like does not limit the shape of the cutting line.

In the following, the invention will be explained in more detail with reference to the accompanying drawing, in which Figure 1 shows two annular blades formed simultaneously from a blank.

Figure 2 is a side view of a central blade and a ring blade mounted on its neck.

Fig. 1 shows a part formed from a preform formed by rolling a sleeve blank and having two similar ring blades 1a and Ib which can be separated by a shape cut, as indicated by line 2. The piece is quenched when its shape has been completed before 20 shapes. The piece is symmetrical with respect to the transverse axis and does not change its shape during tempering. Dimensional changes also remain small. The raw material of the blank is conserved when the shape cut results in a significantly shorter length of the skirt portion 8 than the combined beads of the two ring blades. The grooves 7 are for attaching the ground shoe to the outer surface of the ring blade. Blade pins are later attached to holes 4.

To allow the ring blades to be detached by twisting after the cut, the small areas 3 are cut out and are intended to be punctured so that there is enough clearance to unscrew the ring blades. Current methods for performing post-quenching are laser cutting, incineration, high-pressure water cutting, and plasma cutting. Of these, slightly heat-generating cutting methods, such as laser cutting, burning, and plasma cutting, are the most suitable, whereby the hardness of the cut surface is slightly reduced due to the emission effect. Of course, watercutting also suits the purpose.

Fig. 2 shows both ring blade 1 and center blade 6. The ring blade skirt portion 8 includes a 5 3 rotation-transmitting surface 11, shock-transmitting surfaces 9 and 10, and a potential tire blade extraction surface 12, respectively. impact transfer surface.

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Claims (7)

A method for making a drill bit drill device to produce a sleeve-like annular blade (1) for insertion and locking into a central drill bit (6), the annular front surface having a blade stud (5) and an outer groove (7). at the rear of the body, the skirt portion (S) having surfaces (9-12) imparting impact and / or rotational movement from the central blade (6) to the annular ring (1), wherein the two manufactured annular blades (1) initially have a common blank; separating the skirt portion (8) common to each ring blade (1) and said blank into two ring blades (1a, Ib) by cutting the blank along said skirt portion (8) to form two detachable ring blades (1) comprising rotation of its skirt portion (8) and impact transmission surfaces. Method according to Claim 1, characterized in that the contour cutting line (2) is selected such that the skirt portions (8) of the annular blades become of the desired shape, preferably similar to each other. Method according to Claim 1, characterized in that the piece is quenched 20 prior to forming. Method according to Claim 1, characterized in that the shape cutting is performed by laser cutting, water cutting or the like by a small amount of heating of the annular blade 2. A method according to claim 1, characterized in that the blank of the piece to be cut is first formed by rolling in order to save the raw material. The method according to claim 1, characterized in that the blank CO ^ 30 of the blank is quenched as a symmetrical sleeve, o N-o ^ 7. The method according to claim 1, characterized in that such as a heat-producing cutting method.