CN1617781A - Fixtures - Google Patents

Abstract

The invention relates to a fixing arrangement for holding a cutting tooth on a cutter. The cutting tooth comprises a tool head and a shank. The shank is accommodated in a shank-receiving element of the cutter or a holder connected to said cutter. One or several bearing surfaces of the cutting tooth lies/lie on support surfaces of the cutter. The cutting tooth can be supported in a stable and reliable manner by inclining the support surfaces and the bearing surfaces in a peripheral direction and by providing the cutter with a shoulder which is arranged in the direction of the cutter in an offset position in relation to the bearing surfaces, said shoulder being associated with the cutting tooth at a distance therefrom.

Description

Fixtures

The invention relates to a fastening device for fastening a cutting tooth on a hollow drill bit, wherein the cutting tooth has a head and a shank mounted in a shank mounting seat of the hollow drill bit or a The hollow drill bit is connected to the tool rod mounting seat of the support, and the cutting teeth are abutted against the support surface of the hollow drill bit with one or more abutment surfaces.

Such a fixing device is known from EP04 39821A1. In this case, the hollow drill bits have milled pocket holes, into which a base component is welded in each case. This base member has a tapered shank mount. The shank of the cutter can be inserted into this shank mount. In order to form the conical connection, the tool holder is provided with a conical outer contour. In order to ensure the conical connection, a weight pin is used which connects the base component to the tool shank.

When put into use, especially when subjected to shock loads, the conical connection wears out. As a result, the cutting teeth are no longer fixed without play, resulting in severe continuous wear until the tool breaks.

The technical problem addressed by the invention is to create a fastening device of the type mentioned in the introduction, in which the cutting teeth are securely fastened to the hollow drill bit.

The above-mentioned technical problem is solved in such a way that the bearing surface and the fitting surface are positioned obliquely along the circumferential direction; The platform is arranged correspondingly to the cutting teeth while maintaining a space. The cutting forces generated during the cutting process can mostly be absorbed by the inclined bearing surface. This type of support can also cooperate with the spacer so that the shanks of the cutting teeth are substantially free of cutting forces. This reduces the risk of the tool being damaged. Furthermore, in the event of wear on the bearing surface of the hollow drill bit and/or on the contact surface of the cutter, the spacer also allows the cutter to settle.

According to a preferred design solution of the present invention, the tool holder mounting seat is formed at least partially into a boss surface formed by the boss facing the cutting teeth. For particularly stable mounting of the cutting teeth, provision is made for the hollow drill to provide two contact surfaces for each cutting tooth, and for the two contact surfaces to lie opposite each other. If the fixing device is designed such that the cutting tooth has a threaded section connected to the tool shank, a nut can be screwed on the threaded section, and the cutting tooth is preloaded by means of the nut through the abutment surface Pressing on the supporting surface, a pretensioning device can be formed by the tool rod, which can reliably bear even when subjected to impact tool loads, and the screw connection will not loosen.

The fastening device is advantageously designed such that the tool shank of the cutting tooth is completely surrounded on the peripheral side by the tool shank receptacle at least over a partial region of its longitudinal region extending in the axial direction of the hollow drill bit. Here too, the cutting teeth can thus be reliably prevented from shifting laterally. In this connection it can additionally be provided that the shank of the cutting tooth has at least one alignment recess which is arranged set back relative to the inner wall of the shank receptacle. The cutting teeth can thus be machined dimensionally accurately in the region of their shanks. Excess material can be carried over into the region of the calibration groove.

In a preferred refinement of the invention, the shank of the cutting tooth tapers conically in the direction of its free end at least over a part of its longitudinal length, while the shank receptacle likewise tapers at least partially It is designed to taper conically, and the outer section of the shank is smaller than the inner section of the shank mounting seat. This design achieves simplification of the work of fitting the cutting teeth into the shank mount. If it is provided that the cutting head of the cutting tooth has one or more radial grooves in its radially inwardly oriented region, pockets are formed on the cutting tooth. The stripped material can be collected into these pockets. The exfoliated material thus forms an anti-wear layer.

In order to obtain a higher cutting efficiency compared with known cutting teeth, it is provided that the end region of the cutting head ends on its circumferential side with a triangular-shaped convexly curved profile surface. In addition, it can be provided that a hard material element is inserted in a web arranged in a radially outer region of the cutter, which web extends axially of the hollow drill bit and protrudes from the A substantial part of the cutting tooth, and part of said hard material element protrude radially beyond said web. The hard material elements constitute alignment pins which keep the cutting teeth free to cut throughout the borehole.

In order to further increase the cutting efficiency, it can be provided that the cutting head of the cutting tooth has a top surface in its region facing away from the tool holder, into which a hard material insert (tungsten carbide insert) is inserted.

The invention will be explained in detail below with the aid of an exemplary embodiment shown in the drawings. In the attached picture:

Figure 1 shows a side view of a hollow drill bit;

Fig. 2 represents the perspective view of the hollow drill bit shown in Fig. 1;

Fig. 3 represents the vertical sectional view of described hollow drill bit;

Fig. 4 shows a partial schematic diagram in Fig. 3;

Figure 5 shows a perspective view of a cutting tooth;

Figure 6 shows a perspective rear view of the cutter shown in Figure 5;

FIG. 7 shows a cross-sectional view of the holder of the cutter shown in FIGS. 5 and 6. FIG.

1 and 2 show a hollow drill bit 10 which is produced in one piece from a casting. The hollow drill bit is annular and has a base body 11 . At its lower edge, the basic body has a fastening ring 19 designed in the form of a clip. On the base body 11 on the side facing away from the fastening ring 19 are formed circumferentially distributed fastening projections 21 . The fastening lugs 21 are here spaced apart from one another at the same distance, so that a spacing space 16 results. The base body 11 has webs 15 between the fastening lugs 21 . The webs each form a radially extending end face. All the end faces of the lintel 15 lie on a common plane. A bevel 18 extends from these end faces at an angle thereto. In this case, these bevels 18 face the inner space surrounded by the hollow drill 10 . The end face and the bevel 18 merge at their circumferential ends into the outlet surface 26 of the fastening cam 21 . These exit faces 26 project beyond the end face in the axial direction of the hollow drill. The outlet surfaces 26 each transition into a roof segment 25 which in turn transitions into a support surface 24 . Here, the bearing surface 24 is arranged at an angle to the horizontal. The two bearing surfaces 24 of the fastening cam 21 face each other and are part of the tool receptacle 20 . The tool holder 20 has, between two support surfaces 24, a tool holder 11 with an oval cross-section and an insertion channel 22.1. The insertion channel 22 . 1 opens into a through opening 12 . The through-opening 12 is formed in the base body 11 in the form of a window. The through opening 12 is designed here in such a way that it extends continuously outwards starting from the inner wall 17 . 1 of the main body 11 .

The arrangement and design of the insertion channel 22.1 and the through-opening 12 can also be seen in detail from FIGS. 2 and 4 . As can be seen from FIG. 2 , the cutting teeth 30 can be inserted into the tool holder 20 . The design of the cutting teeth 30 can be seen in FIGS. 5 to 7 . Accordingly, the cutting tooth 30 has a head 31 on which a shank 32 is formed. The cutter head 31 is equipped with a carbide insert 35 . The shank 32 has a threaded section 33 at its free end.

The cutting tooth 30 is inserted with its shank 32 into the insertion channel 12.1. In the assembled state, the cutting tooth 30 bears with a corresponding mating surface on the bearing surface 24 .

The threaded section 33 protrudes into the region of the through-opening 12 so that a nut 34 can be screwed onto it. The cutting tooth 30 can be clamped on the bearing surface 24 by means of the nut 34 . Since the shank of the cutting tooth 30 has a cross-sectional shape designed to match the contour of the insertion channel 22.1, it is fixed in a non-rotatable manner. As shown in FIG. 1 , the cutting tooth 30 has two profiled surfaces 36 , which merge without steps into the exit surfaces of the support section 25 .

For alignment of the hollow drill 10 , projections 13 are provided on the outer surface of the hollow drill upper base body 11 . They are equipped with wear-resistant elements 14 made of cemented carbide.

The base body 11 also has projections 17.2 in the region of the inner wall 17.1, which protrude into the interior of the hollow drill 10 and serve there to optimize the wear conditions.

5 to 7 show the design of the cutting teeth 30 in detail. The cutting tooth 30 has a cutting head 31 on which a cutting shank 32 is formed by a round transition. One end of the cutter bar 32 facing away from the cutter head 31 extends into a threaded section 33 . The cutter head 31 has an upper top surface 31.1 in which a carbide insert 35 is accommodated. In order to form a mounting seat for a carbide insert designed as a cylindrical pin, a web 37.1, 37.2 is located at the front and rear, starting from the top surface 31.1.

It can be seen from FIG. 5 that the top surface 31.1 merges in the region of the inner side of the cutting tooth 30 into a steeply concave arched wall 38.2, which is subdivided in the longitudinal direction by two ribs 38 and a web 37.1. The ribs 38 and the webs 37.1 form recesses 38.1 which serve as pockets for receiving the stripped material. On the rear side, the top surface (as shown in FIG. 6 ) transitions into a wall 38 . 3 extending parallel to the axis of rotation of the core drill 10 . This wall 38.3 has a web 37.2. The lintel 37.2 is equipped with a hard material element 39.3. This hard material element protrudes beyond said web 37.2. The walls 38 . 2 and 38 . 3 merge into one another on the sides of the cutting tooth 30 by means of the profiled surface 36 . The shaping surface 36 is of triangular design and is convexly curved.

The blade 32 is connected to a base portion 39 of the blade 31 . The cross section of the cutter bar 32 is designed to be oval, as shown in FIG. 7 . The knife shaft 32 is provided with alignment grooves 32.1 on both longitudinal sides. On the side of the rod 32 there is provided a chamfer 32.2 which also serves for alignment. Four dimensionally precise shaft regions can thus be forged between the calibration recess 31.1 and the chamfer 32.2. They prevent the shank from jamming when the shank is loaded into the shank mount 22 .

Claims (12)

1. one kind is used for going up the fixedly fastening devices of cutting teeth (30) at a hollow boring bit (10), wherein, described cutting teeth (30) has a cutter head (31) and a knife bar (32), this knife bar (32) be installed in the knife bar mount pad (22) of described hollow boring bit (10) or with a bearing that this hollow boring bit (10) is connected on the knife bar mount pad in, and described cutting teeth (30) abuts on the bearing surface (24) of described hollow boring bit (10) with one or more binding faces (39.1), it is characterized by: described bearing surface (24) and binding face (39.1) are along location, peripheral, oblique ground, and described hollow boring bit (10) has along the axial boss of arranging corresponding to described binding face (39.1) (27) of this hollow boring bit (10), and this boss is provided with accordingly with described cutting teeth (30) under the situation that maintains a clearance space (27.1).

2. according to the described fastening devices of claim 1, it is characterized by: described knife bar mount pad (22) partly is formed in the boss face that faces described cutting teeth (30) that is made of described boss (27) at least.

3. according to claim 1 or 2 described fastening devicess, it is characterized by: described hollow boring bit (10) provides two binding faces (39.1) for each cutting teeth (30), and these two binding faces (39.1) are opposite each other.

4. according to each described fastening devices in the claim 1 to 3, it is characterized by: described cutting teeth (30) has a thread segment (33) that is connected with described knife bar (32), a nut (34) can be tightened onto on this thread segment (33), described cutting teeth is pressed on the described bearing surface (24) by described binding face (39.1) in advance tightly by this nut (34).

5. according to each described fastening devices in the claim 1 to 4, it is characterized by: the knife bar (32) of described cutting teeth (30) is surrounded by described knife bar mount pad (22) fully at its part zone avris last week along the axially extended longitudinal region of hollow boring bit at least.

6. according to the described fastening devices of claim 5, it is characterized by: the knife bar (32) of described cutting teeth (30) has at least one and is set to the alignment receptacle (32.1) of moving behind the inwall with respect to described knife bar mount pad (22).

7. according to each described fastening devices in the claim 1 to 6, it is characterized by: the knife bar (32) of described cutting teeth (30) at least on the part of its longitudinal length towards its free-ended direction taper be tapered, and described knife bar mount pad (22) subregion contraction at least similarly, and the outer cross section of described knife bar (32) is less than the interior cross section of described knife bar mount pad (22) with being designed to taper.

8. according to each described fastening devices in the claim 1 to 7, it is characterized by: the cutter head (31) of described cutting teeth (30) radially has one or more radial grooves (38.1) at it in the zone of interior orientation.

9. according to each described fastening devices in the claim 1 to 8, it is characterized by: described cutter head (31) is sentenced forming face (36) end that leg-of-mutton arching becomes convex surface at the end regions of its circumference.

10. according to each described fastening devices in the claim 1 to 9, it is characterized by: described cutter head (31) radially is on the outside zone at it and is equipped with one or more hard material elements (39.3).

11. according to the described fastening devices of claim 10, it is characterized by: described hard material element (39.3) is loaded in the lintel (37.2), this lintel is located at that of described cutting teeth radially is in the outside zone and along the essential part (39) that extends axially and protrude in described cutting teeth (30) of described hollow boring bit, described hard material element (39.3) radially protrudes in described lintel (37.2) partly.

12. according to each described fastening devices in the claim 1 to 11, it is characterized by: the cutter head (31) of described cutting teeth (30) has an end face (31.1) in its zone back to described knife bar (32), and a hard material insert (carbide alloy inserts (35)) is encased in this end face (31.1).

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