EP1581354B1 - Method and device for producing a hard metal tool - Google Patents

Abstract

The method has a first material of lesser hardness acting as a rod-shaped carrier for a second material of greater hardness, each materials formed within a respective extrusion press tool (P1,P2) and the plastic mass flow of the greater hardness material fed to the extrusion press tool for the lesser hardness material for providing a common plastic mass flow in the form of a rod-shaped body (9) with a core (9a) and an outer region (9b). An Independent claim for a device for manufacture of a hard metal workpiece is also included.

Description

The invention relates to a method for producing a rod-shaped, at least two materials of different hardness having carbide tool, wherein the first material has the lower hardness and forms a rod-shaped support for the second, harder material.

Methods for producing rod-shaped carbide tools, in particular carbide boring tools, are known for example from DE 40 21 383 C2, DE 41 20 166 C2, WO 01/17705 A2, DE 102 29 325.2 and DE 102 29 326.0. In these known methods, in each case an extrusion die is used, by means of which a cylindrical body consisting of plastic mass is produced, which has one or more recesses extending in its interior. The extrusion die has a die with a narrowing portion and a die tip which forms a cylindrical channel. None of these known methods is used to produce a rod-shaped, at least two materials of different hardness having carbide tool, wherein the first material has the lower hardness and forms a rod-shaped support for the second, harder material.

From US 4,762,445 A a method for producing a drilling tool is known, which has a cylindrical base body. This is conically formed in an end region. It consists of a first material, for example tungsten carbide, which is unbreakable, tough, easily solderable or weldable and easy to grind. In this body grooves are introduced, in particular ground. These grooves are filled with a second, extremely hard material, for example Diamond or cubic boron nitride. This is followed by a sintering process using high pressure and high temperature to firmly bond the two materials together. The said grooves are shaped and positioned such that the diamond layer or the cubic boron nitride forms the cutting edge of the drilling tool.

The disadvantage of this known procedure is that an introduction of grooves in the body, which usually takes place by means of a grinding process, is expensive. The ground grooves have only a small depth, d. H. they have only a small extension in the longitudinal direction of the tool. This has the disadvantage that the ultimately produced drilling tool can be reground at most a few times and for this reason only a limited amount of time can be used.

It is already known from GB 882 693 A to combine mass flows of different metallic materials. This is done using a nozzle that is placed between two containers. The mass flows are provided by different plungers whose extensions project into one of the containers. The aim of this citation is the production of a bimetal with eccentric Zugkraftschwerpunkt. Preparation of a two-component metal rod in which one component completely surrounds the other component is not possible by the method described in GB 882 693 A.

It is also already known from US Pat. No. 3,457,760 A to combine mass flows of different metallic materials. This is done using a special mechanism that has an electrically heated container. This is supplied to an already existing two-component metal rod, wherein the second metal component forms a coating of the first metal component. The said metal components are pressed through a specially shaped die using a plunger. At the exit of the nozzle, a two-component metal rod is provided, wherein the second metal component forms a coating of the first metal component. By means of the method described in US Pat. No. 3,457,760 A, only cross-sectional changes of an already existing rod can be made.

From JP-A-60 059 001 and the associated English translation of the abstract, a method for producing a rod-shaped blank having at least two different materials is already known, in which the first material forms a rod-shaped carrier for the second material. This known method is carried out by means of a pressing tool which has a second cylinder arranged within a first cylinder. On the output side, both cylinders have nozzles through which the extruded material is output in the form of a common plastic mass flow.

The invention has for its object to provide a way to produce a carbide tool in which the disadvantages described above do not occur.

This object is achieved by a method having the features specified in claim 1. Advantageous embodiments and further developments are specified in the dependent claims 2-10. Claims 11-16 relate to a device for carrying out the method according to one of claims 1-10.

The advantages of the invention are in particular that an introduction of grooves in the body is not necessary, since the second material is already introduced during the extrusion in the first material. This also makes it possible, in particular, to introduce the second material not only into edge regions, but also into interior regions of the first material. The second material may have a large extent in the axial direction of the rod-shaped tool, so that a frequent re-sharpening of the tool can easily take place. This significantly prolongs the service life of the tool.

Figur 1

eine Skizze zur Veranschaulichung eines ersten Ausführungsbeispiels für die Erfindung;

Figur 2

eine Skizze zur Veranschaulichung eines zweiten Ausführungsbeispiels für die Erfindung und

Figur 3

eine Skizze zur Veranschaulichung eines dritten Ausführungsbeispiels für die Erfindung.

Further advantageous features of the invention will become apparent from the following explanation of exemplary embodiments with reference to FIGS. It shows

FIG. 1

a sketch illustrating a first embodiment of the invention;

FIG. 2

a sketch illustrating a second embodiment of the invention and

FIG. 3

a sketch illustrating a third embodiment of the invention.

FIG. 1 shows a sketch to illustrate a first exemplary embodiment of the invention. Based on this sketch, the basic operation of the invention will be explained.

By means of the device shown in Figure 1, a rod-shaped blank for a carbide tool is produced, which has two materials of different hardness. The first material has the lower hardness and forms a rod-shaped carrier for the second, harder material. The first material is a hard metal, which has a high toughness and thus a high resistance to breakage. Since the first material forms the carrier for the second material, the ultimately produced tool is shatterproof due to the toughness of the first material. The second, harder material is also preferably a cemented carbide, but has a different composition than the first material to ensure the desired greater hardness. The second, harder material in this embodiment forms the core of the first material, i. H. its longitudinally extending central axis, but may also be arranged off-center according to further, not shown in the figure embodiments.

The production of such a tool is done as follows:

In a first extrusion tool P1, the first material, which is in the form of a plastic mass flow 8, is pressed through the wide region 1 of a pressing nozzle in the direction 7 to the nozzle mouthpiece 2. Between the wide portion 1 and the nozzle tip 2, a narrowing portion 1a is provided. The nozzle mouthpiece forms a cylindrical channel.

The second material is provided by a second extrusion tool P2. In this second extrusion die, the second material, which is also in the form of a plastic mass flow, is pressed through the wide region 11 in the direction 7 to the nozzle mouthpiece 12. Between the wide portion 11 and the nozzle tip 12, a narrowing portion 11a is provided. The nozzle orifice 12 forms a cylindrical channel through which the second material in the form of a mass flow to a supply line 4 is output. This feed line 4 is provided between the two extrusion dies P1 and P2. Through this supply line, the material provided by the second extrusion tool P2 is fed to the first extrusion tool P1. The first extrusion tool P1 has in the region of the pressing nozzle, preferably in the region of the nozzle mouthpiece 2, an inlet opening 13 through which the second material provided via the feed line 4 is received.

The nozzle mouthpiece 2 is formed in two parts in the embodiment shown, wherein the first part 5a is formed integrally with the wide region 1 and the narrowing part 1a of the pressing nozzle. The second part 5b of the nozzle tip 2 forms its end region, which can be removed from the first part 5a, for example unscrewed.

In the first region 5a of the nozzle tip 2, a holder 3 is inserted, which is a concentric retaining ring. This can easily be inserted into the extrusion tool P1 when the end region 5b is removed and can also be easily removed from it.

The holder 3 has a channel 3a, the conclusion forms a Halteraustrittsdüse 10. On the input side, the channel 3a is connected to a channel 14, which is provided in the housing of the nozzle orifice 2.

The second material produced by the second extrusion tool P2 and made available via the feed line 4 occurs through the inlet opening 13 in the first extrusion tool P1 and is passed there through the channel 14 to the channel 3a of the holder 3. The emerging from the outlet nozzle 10 of the holder 3 second material is pressed into the first mass flow. Since the outlet nozzle 10 is arranged centrally in the embodiment shown, the second material forms after pressing the soul of the first material.

As a result, the cylindrical body 9 discharged from the first extrusion die P1 has a support constituting the entire outer portion 9b of the cylindrical body 9 and made of the first material. The core 9a of the cylindrical body 9 is formed by the second material. This is illustrated in the figure 1 bottom right in the form of a cross-sectional view.

As an alternative to the embodiment described above, the following modifications are possible:

A first modification is to design the holder 3 not in the form of a holder ring, but in the form of a pin-shaped holder element. A second modification consists in pressing the second material not in the form of a mass flow having a circular cross-sectional area, but in the form of a mass flow having a non-circular cross-sectional area into the first material. Advantageously, for example, an elongated cross-sectional shape which extends over half or even over the entire inner diameter of the nozzle orifice. This procedure allows, for example, the production of a drilling tool, in which the cutting area is formed by the second, harder material.

After all, the illustrated embodiment discloses a method and an apparatus for producing a rod-shaped carbide tool having two materials of different hardness. The first material has the lower hardness and forms a rod-shaped carrier for the second, harder material. The first material will be within a first Extruding tool in the form of a plastic mass flow in the direction of the nozzle tip of a pressing die pressed. The second material, which is in the form of a plastic mass flow and which is preferably provided by a second extrusion tool, is pressed into the first mass flow within the first extrusion tool.

The bar-shaped, preferably cylindrical body output by the first extrusion tool P1 is further processed into a finished carbide tool, preferably a carbide-boring tool or a carbide-milling tool.

As part of this further processing, the body leaving the first extrusion tool P1 is cut to a desired length outside the extrusion tool P1. Subsequently, the cut-to-length body can be twisted uniformly by means of a friction surface arrangement-as described in more detail, for example, in WO 01/17705 A2. The cut and twisted or untwisted body is dried, optionally provided on its outer periphery with one or more chip chambers and finally sintered.

By doing so, one obtains a carbide tool that is shatterproof due to the properties of the first material and is extremely hard due to the properties of the second material in the work area.

2 shows a sketch to illustrate a second embodiment of the invention, which corresponds to a development of the embodiment shown in the figure 1. According to this second embodiment, in addition, using a third extrusion die P3, a third material having either the same properties as the second material or having other desired properties is additionally provided. This third material is fed via a further supply line 20 to the first extrusion tool P1.

The third material produced by the third extrusion die P3 and made available via the feed line 20 enters through an inlet opening 18 into the first extrusion tool P1 and is passed there through a channel 19 to a channel 3b of the holder 3. The third material emerging from the outlet nozzle 10b of the holder 3 is also pressed into the first mass flow as the second material emerging from the outlet nozzle 10a of the holder 3.

In this embodiment, a cylindrical body 9 emerges from the first extrusion die P1. This has a support which forms the entire outer region of the cylindrical body and consists of the first material. Within this carrier 9b are - as is apparent from the upper cross-sectional view in Figure 2 bottom right - two deposits provided. The insert 9d consists of the second material and the insert 9c of the third material.

A modification of the embodiment according to FIG. 2 consists in choosing the outlet nozzles 10a and 10b of the holder 3 rectangular such that the inserts 9c 'and 9d' form the cutting edges in the finished drilling tool. This is illustrated in the lower cross-sectional representation in Figure 2 bottom right. The bent shape of the inserts can be produced by virtue of the fact that the outlet nozzles 10a and 10b of the holder 3 already have a curved shape or in that the cylindrical body output by the first extrusion tool P1 is first cut to length outside the first extrusion tool P1 and then twisted in the desired manner ,

3 shows a sketch to illustrate a third embodiment of the invention, which corresponds to a development of the embodiment shown in Figure 2.

In this embodiment, in addition to the embodiment shown in Figure 2, a control unit 21, a sensor 22, a valve 23 and a valve 24 are provided. The valve 23 is located between the second extrusion die P2 and the first extrusion tool P1 in the supply line 4. The valve 24 is disposed in the supply line 20 between the third extrusion tool P3 and the first extrusion tool P1. The sensor 22 is provided outside of the first extrusion tool P1 in the outlet region of the cylindrical body 9 and serves for a Wegs- or exit velocity measurement or for detecting when the issued from the first extrusion die P1 cylindrical body has reached a predetermined position. If the output cylindrical body has reached the predetermined position, the sensor system 22 provides an output signal ss.

This is supplied to the control unit 21 and taken into account by the latter in the determination of control signals s1, s2, s3 and s4. The control signal s1 serves to adjust the speed of movement of the piston 6 arranged in the second extrusion die P2. The control signal s2 serves to control the valve 23. The control signal s3 serves to set the speed of movement of the piston 17 provided in the third extrusion die P3. The control signal s4 serves for control of the valve 24. Further control signals of the control unit 21 are used to adjust the volume flow of the first material in the first extrusion tool P1.

The said control or adjustment of the volume flows takes place for example such that the second and third material, which forms the cutting area of the later drilling tool, is pressed into the first material only in the front half of the drilling tool. This takes into account the fact that the rear portion of the finished drilling tool is clamped during operation in a chuck and at no time forms the cutting area. This approach involves a cost saving because the second and third materials, which form the cutting area of the drilling tool and therefore must be extremely hard, are generally much more expensive than the first material which has lower hardness.

Preferably, all the materials used are cemented carbide components which have the respective desired properties. This also has the advantage of a simplified recycling, because the entire product consists only of hard metal components. There are no solder joints and there are no different substances to dispose of.

Alternatively, it is also possible to use polycrystalline diamond (PCD) as a harder material which forms the cutting area of the later drilling tool, which is also used in previously known drilling tools in the cutting area.

The method according to the invention and the device according to the invention can be used after all to produce rod-shaped carbide-boring or milling tools, which has as carrier material a first carbide grade with high toughness and comparatively low hardness. Such carbide grades have, for example, a high cobalt content and a comparatively coarse grain size that is not suitable for the cutting area of a carbide tool. Such carbide types are relatively inexpensive. In this carrier material cutting material is pressed in the context of an extrusion process, which is preferably a carbide with very high hardness and finest grain size to meet the requirements in the cutting area of a carbide tool justice. Alternatively, polycrystalline diamond may also be used in the cutting area.

The tools produced can also be reamers.

The tools produced can-as it is known, for example, from WO 01/17 705 A2-have internal cooling channels through which a liquid coolant is guided into the working area of the respective tool during the working operation of the tool.

As an alternative to the above embodiments, screw presses can also be used instead of piston presses if the volume flow is known for each press involved in the production process.

LIST OF REFERENCE NUMBERS

P1

first extrusion tool

P2

second extrusion tool

P3

third extrusion tool

1

wide area of a pressing nozzle

1a

narrowing area of the pressing nozzle

2

Nozzle mouthpiece

3

holder

3a

Channel in the holder

3b

Channel in the holder

4

supply

5a

first area of the nozzle mouthpiece 2

5b

End portion of the nozzle tip 2

6

Piston of the second extrusion tool

7

pressing direction

8th

plastic mass

9

cylindrical body

9a

Soul of second, harder material

9b

Carrier made of first, softer material

9c

Insert made of second, harder material

9d

Insert of third, harder material

10

Halteraustrittsdüse

10a

Halteraustrittsdüse

10b

Halteraustrittsdüse

11

wide area of the second die

11a

narrowing area of the second squeeze nozzle

12

Nozzle mouthpiece of the second press nozzle

13

inlet opening

14

Channel in the nozzle mouthpiece 2

15

wide area of a third die

15a

Narrowing area of the third die

16

Nozzle mouthpiece of the third press nozzle

17

Piston of the third extrusion tool

18

inlet opening

19

Channel in the nozzle mouthpiece 2

20

supply

21

control unit

22

sensors

23

Valve

24

Valve

s1, s2, s3, s4

control signals

ss

Output signal of the sensor 22

Claims (16)

1. Method of producing a bar-shaped hard metal tool comprising at least two materials of different hardness, wherein the first material has the lower hardness and forms a bar-shaped support for the second, harder material, wherein

   - the first material is provided within a first extrusion tool (P1) in the form of a plastic mass flow,

   - the second material is provided within a second extrusion tool (P2) similarly in the form of a plastic mass flow,

   - the second material is fed to the first extrusion tool (P1) by way of a channel (4) connecting the two extrusion tools and forced within the first extrusion tool (P1) into the first mass flow,

   - a common plastic mass flow of the first and second material is issued from the first extrusion tool as a bar-shaped body in which the first material forms a bar-shaped support for the second material and

   - the bar-shaped body issued from the first extrusion tool is further processed to form a hard metal tool,

   - wherein the required volume flows of the materials are set in dependence on output signals of a sensor.
2. Method according to claim 1, characterised in that the second material is forced into the first mass flow with use of a nozzle.
3. Method according to claim 2, characterised in that the second material is forced into the first mass flow with use of a nozzle with a non-round cross-sectional shape.
4. Method according to claim 3, characterised in that the second material is forced into the first mass flow with use of a nozzle with elongate cross-sectional shape.
5. Method according to any one of the preceding claims, characterised in that measurement of the exit speed of the cylindrical body from the first extrusion tool (P1) is carried out by means of the sensor.
6. Method according to claim 5, characterised in that the speed of the mass flow of each of the first and second extrusion tools (P1, P2) is undertaken by respective control of the movement of a piston in dependence on the output signals of the sensor.
7. Method according to any one of the preceding claims, characterised in that the material provided by means of the second extrusion tool (P2) is conducted to the first extrusion tool (P1) by way of a controlled valve.
8. Method according to claim 7, characterised in that the valve is controlled in dependence on the output signals of a sensor.
9. Method according to any one of claims 6 to 8, characterised in that control of the movement of the piston and/or the valve is undertaken in such a manner that forcing of the second material into the first mass flow takes place only within predetermined time intervals in such a manner that the second material is forced merely into the front region of the body leaving the first extrusion tool (P1).
10. Method according to any one of the preceding claims, characterised in that further materials each present in the form of a plastic mass flow are forced into the first mass flow within the first extrusion tool (P1).
11. Device for carrying out the method according to any one of claims 1 to 10, comprising

    - a first extrusion tool (P1) within which the first material can be pressed in the form of a plastic mass flow in direction towards the nozzle mouthpiece (2) thereof,

    - a second extrusion tool (P2) by means of which the second material is provided in the form of a plastic mass flow,

    - a channel (4) connecting the two extrusion tools,

    - a further nozzle (10) by which the second material can be forced into the first material,

    - a control unit (21) provided for setting the required volume flows of the materials and

    - a sensor (22) connected with the control unit (21),

    - wherein the control unit (21) is provided for setting the required volume flows in dependence on output signals (ss) of the sensor.
12. Device according to claim 11, characterised in that the further nozzle (10) has a non-round cross-sectional shape.
13. Device according to claim 11, characterised in that the further nozzle has an elongate cross-sectional shape.
14. Device according to any one of claims 11 to 13, characterised in that it comprises a valve (23) arranged in the channel (4) connecting the two extrusion tools.
15. Device according to claim 14, characterised in that the control unit (21) is provided for controlling the valve (23).
16. Device according to any one of claims 11 to 15, characterised in that it comprises at least one further extrusion tool (P3), which is connected with the first extrusion tool (P1) by way of a channel (20), wherein the at least one further extrusion tool (P3) is provided for preparing a further material present in the form of a plastic mass flow.

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