WO2018000001A1

WO2018000001A1 - Method for mechanically healing functional cemented carbide or cermet surfaces

Info

Publication number: WO2018000001A1
Application number: PCT/AT2017/000047
Authority: WO
Inventors: Glätzle JOHANNES; Christian PAULWEBER; Manuel WALCH
Original assignee: Ceratizit Austria Gesellschaft M.B.H
Priority date: 2016-06-27
Filing date: 2017-06-09
Publication date: 2018-01-04
Also published as: AT15412U1

Abstract

Disclosed is a method for mechanically healing functional cemented carbide or cermet surfaces (2). An exposed cemented carbide or cermet surface (2) that does not adjoin a cutting edge is blasted with a particle beam (S) in a blasting process in order to heal microcracks and/or superficial fractures.

Description

METHOD FOR THE MECHANICAL CLEANING OF FUNCTIONAL HARD METAL OR CERMET SURFACES

The present invention relates to a method for the mechanical annealing of functional hard metal or cermet surfaces, use of a directional particle beam with an exposed functional hard metal or cermet surface not adjacent to a cutting edge and a component made of hard metal or cermet. Components made of cemented carbide or cermet come in one

A variety of applications are used, where it depends on a particularly good resistance to mechanical stress and wear. A particular field of application in which these materials are used very frequently is e.g. given by cutting tools, where often at least the actual cutting areas of hard metal or cermet are formed. Carbide (cemented carbide) and cermet are

Composite materials in which hard material particles are embedded in a ductile metallic matrix, the proportion of hard material particles in

Weight percent is significantly greater than the proportion of the metallic matrix. The metallic matrix is usually formed by cobalt, nickel and / or iron or a base alloy of one of these elements, predominantly a Co base alloy, a Ni base alloy or a Co-Ni base alloy. In the case of cemented carbide, the metallic matrix is usually one

Co-based alloy. Base alloy of a metal means that this metal forms the main component of the alloy. In addition to the mentioned

Elements can be solved even more elements in smaller amounts in the metallic matrix. The hard material particles are usually by carbides or carbonitrides of metals of groups IV to VI of

Periodic table formed. In the case of hard metal, the majority of the hard material particles is formed by WC (tungsten carbide), although in smaller quantities other hard material particles may additionally be present.

For the purpose of the preparation of cutting edges in carbide components are already partially used methods in which the cutting edges and immediately adjacent areas with a particle beam be treated, for example, to achieve a desired rounding in the region of the cutting edge.

Hardmetals and cermets stand out in comparison to many others

Materials characterized by high hardness and can be very high

Resist pressure loads. With tensile loads, however, there is the risk of material failure, as opposed to hard metal or cermet

Tensile stresses a significantly higher sensitivity than opposite

Compressive stresses. When using cemented carbide or cermet, constructive attempts are often made to keep tensile loads as low as possible, and such can not always be avoided depending on the field of application.

It is an object of the present invention to achieve the best possible resistance of components made of carbide or cermet against tensile loads and thus to reduce the probability of failure and tendency to fracture of such components.

The object is achieved by a method according to claim 1. Advantageous developments are specified in the dependent claims.

It is a process for the mechanical annealing of functional carbide or cermet surfaces. An exposed hard metal or cermet functional surface not adjacent a cutting edge is blasted by a jet blast shot to cure microcracks and / or surface dislocations. By blasting the exposed functional surface of the cemented carbide or cermet, microcracks, i. small cracks of microscopic magnitude, and

Surface aberrations, e.g. the result of previous ones

Manufacturing steps can be cured efficiently. In this way, the probability of failure of the device having the functional cemented carbide or cermet surface can be significantly reduced. There are thus damage to the carbide or

Cermet surface healed, which is typically the starting point of a Cracking and thus a component failure are. Consequently, a significantly higher component safety is achieved and the component strength is increased.

According to a development, the blast treatment is carried out in such a way that compressive stresses are introduced in a region of the hard metal or cermet close to the surface. The targeted introduction of compressive stresses can in particular on the jet pressure, the Einstrahlwinkel of

Particle beam relative to the exposed functional surface of the

Carbide or cermets, the material used of the particles of the

Particle beam, the shape of the particles and the particle size are controlled. In particular, the local introduction of compressive stresses in

near-surface area leads to a significant improvement in the

Resistance of the component made of hard metal or cermet and thus to a lower probability of failure.

According to a development, the functional carbide or

Cermet surface a contact surface for supporting the component to another component, a holding surface for cooperation with a holding element or a transition surface between two such surfaces. In particular, such surfaces of components made of hard metal or cermet are often exposed to a tensile load in use, so that a

Component failure takes place on the basis of microcracks and / or surface distortions in the region of such a surface. Consequently, in this case, the probability of failure of the component can be significantly improved.

According to one embodiment, the functional carbide or

Cermet surface neither blasted nor coated after blasting. In this case, the improvements achieved by the blast treatment are reliably maintained and the risk of

Material failure remains reduced.

According to a development, the functional hard metal or cermet surface is ground before the blast treatment. It has been found that in particular ground carbide or cermet surfaces due to by the grinding process caused surface dislocations and

Micro damages are often the starting point of material failure of a hard metal or cermet component. The blast treatment of such ground surfaces can significantly reduce the probability of failure.

According to one embodiment, the functional carbide or

Cermet surface machined prior to blasting by electro-erosion or laser machining. In particular, such treatments lead to micro-damage of the functional carbide or cermet surface, so that the downstream blast treatment

Failure probability can be significantly reduced.

According to another embodiment, the functional hard metal or cermet surface is subjected to the blast treatment in a sintered state. Already in the production of the component from hard metal or cermet in a powder metallurgical production process

Damage at the microscopic level arising after the

Sintering step to densify the component to the final density as micro-cracks or surface dislocations come to light. By the downstream

Beam treatment can be significantly reduced in such a case, the probability of failure of the components.

According to a development, the particles of the particle beam to glass beads and / or zirconium oxide. In this case, the desired effects of the blast treatment due to the rather round particle shape are achieved reliably even without significant removal of material on the component made of hard metal or cermet, which is opposite to the e.g. also possible in principle

Use of e.g. Corundum as blasting agent is advantageous.

The particles of the particle beam preferably have a round shape

Surface structure in order to minimize unwanted material removal in the blast treatment. According to a development, the jet treatment is carried out such that the particle beam at an angle of incidence α> 40 ° to the functional

Surface is supplied. The angle of incidence is defined herein as the angle formed between the exposed functional surface and the impinging particle beam. Due to the relatively large angle of incidence, in addition to the healing of microcracks and

Surface distortions are also introduced targeted compressive stresses in the near-surface region and a material hardening in the near-surface region can be achieved.

The object is also achieved by the use of a directional particle beam at an exposed functional hard metal or cermet surface not adjacent to a cutting edge for mechanical annealing of microcracks and / or surface dislocations.

The object is further achieved by a component made of hard metal or cermet according to claim 12. Advantageous developments are specified in the dependent claims. The cemented carbide or cermet member has a non-cutting edge exposed functional carbide or cermet surface which is blasted with a particle beam for annealing microcracks and / or surface dislocations. The functional hard metal or cermet surface thus has recognizable properties, which are due to the blast treatment, so that the surface has the properties of a

Particle beam blasted surface. In particular, the

Surface thereby recognizable, by the impact of the particles of the

Particle beam caused local microscopic deformations and a voltage gradient in the direction perpendicular to the functional hard metal or cermet surface. Compared to a component made of hard metal or cermet, in which the exposed functional surface is not irradiated, the component with the blasted surface has a significantly reduced probability of failure and a much lower tendency to breakage. According to a development, the functional carbide or

Cermet surface in a shallow area compressive stresses on. In this case, the tendency to break and the probability of failure are reduced significantly compared to an unshielded functional hard metal or cermet surface.

According to a further treatment is the functional carbide or

Cermet surface ground and blasted. In particular ground carbide or cermet surfaces due to due to the grinding process surface dislocations and / or micro damage

The starting point of a material failure of a component made of hard metal or cermet can be, by the blast treatment of such

Ground surfaces the probability of failure are significantly reduced.

Further advantages and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures.

From the figures show:

1 shows a schematic representation of a component made of hard metal or

Cermet with functional carbide or cermet surfaces;

2 shows a schematic representation of a blasting treatment of an exposed functional not adjacent to a cutting edge

Hard metal or cermet surface;

Fig. 3: a scanning electron micrograph with 150-fold

Enlargement of a functional hard metal surface with a typical grinding scratch caused by a grinding process;

4: a scanning electron micrograph of the functional

Carbide surface of Figure 3 with 1200-fold magnification with a more enlarged section in the area of the grinding call. FIG. 5 shows a scanning electron micrograph corresponding to FIG. 3 with a magnification of 150 times of the same functional hard metal surface after a jet treatment with a particle beam; FIG.

Fig. 6: a scanning electron micrograph with 1200 times

Enlargement of the functional carbide surface after blasting with the particle beam; and

Fig. 7: a scanning electron micrograph with 10,000 times

Enlargement of an exposed functional carbide or

Cermet surface with typical surface dislocations due to sub-optimal grinding parameters.

EMBODIMENT An embodiment of the present invention will be described below in more detail with reference to the figures.

In Fig. 1 is an example of a component 1 made of hard metal or cermet with a not adjacent to a cutting edge, exposed functional

Carbide or cermet surface 2 a replaceable via a screw interchangeable head for a cutting tool, in particular a drill or cutter, shown schematically. The component 1 has a working area 1a, on which cutting edges for a machining operation can be formed, in particular by grinding. The exposed functional hard metal or cermet surface 2 not adjacent to a cutting edge is in the embodiment

in particular a contact surface for supporting the component 1 on a corresponding surface of a base body. In the present case, the main body may in particular be formed, for example, by a tool shank made of a tougher material, such as tool steel. In the embodiment, the component 1 further comprises a threaded portion 3, on which the component is provided with an external thread. In the concrete example shown, the component 1 made of hard metal or cermet also has another not adjacent to a cutting edge, exposed functional carbide or Cermet surface 4, which in this case is also a contact surface for supporting the component 1 on a corresponding surface of the base body. Although the component 1 of cemented carbide or cermet in the concrete

described embodiment is a replaceable replaceable head for a cutting tool, other embodiments are possible in which the component 1 is made of hard metal or cermet for another purpose. Although the exposed functional hard metal or cermet surface 2, not adjacent to a cutting edge, is an abutment surface in the concretely illustrated embodiment, it is e.g. also possible that this surface has a holding surface for cooperation with a holding element, such as e.g. a clamping claw or the like, a

Transition area between such areas or another area is.

Although in the specific embodiment, two such exposed hard metal or cermet functional surfaces 2, 4 are formed, it is also e.g. also possible that the component 1 has only one such surface or more than two such surfaces. In the method according to the embodiment, which is not connected to a

Cutting edge adjacent, exposed functional carbide or

Cermet surface 2 subjected to a blasting treatment, in which the exposed functional surface 2 of the component 1 is irradiated with a particle beam S, as shown schematically in Fig. 2. The blast treatment is carried out in a pressure blasting process in which the particle beam S is supplied to the exposed functional surface 2 at a predetermined angle of incidence. The angle of incidence formed between the exposed functional surface 2 and the supplied particle beam S is preferably at least 40 °, in order to achieve a sufficient energy input into the material of the component 1. The blast treatment can be carried out particularly preferably as dry blasting. The particles of the

Particle beam S can be e.g. Have glass beads, zirconium oxide and / or corundum, in particular be formed by these substances. The

used particles of the particle beam S preferably have a round Shape of the individual particles on and no sharp-edged or angular shape. In order to reliably prevent an undesirably high material removal on the component 1, use of glass beads and / or zirconium oxide is preferred over use of, for example, corundum. The functional carbide or cermet surface 2 subjected to the blast treatment is exposed, ie in particular no additional hard coating or the like is formed on the hard metal or cermet surface 2.

In the specific embodiment, the exposed functional cemented carbide or cermet surface 2 is ground prior to blasting in a grinding process. In particular, in a well-known manner

Diamond grinding wheels are used. The grinding is done in particular for the purpose of a desired geometric

To achieve the consistency of the functional carbide or cermet surface with extremely low tolerances.

Fig. 7 is an electron micrograph of 10,000 times

Enlargement of such a ground functional surface 2 in a component 1 made of hard metal, wherein the grinding parameters were not quite optimal. In Fig. 7 it can be seen that the grinding with sub-optimal

Grinding parameters on the functional surface 2 microcracks or

Surface disruptions 5 leaves, which have a negative impact on the susceptibility to breakage and probability of failure of the component 1. In the electron micrograph with 150-fold magnification of a ground functional hard metal surface 2 in a component 1 made of hard metal in Fig. 1 is in the circled area by a

See grinding process caused surface dislocation 5 in the form of a grinding marks. In the electron micrograph with 1,200 times

Magnification of the same area in Fig. 4, this surface dislocation 5 is to recognize even more clearly, wherein in the right part of Fig. 4 is an even more enlarged shot from the immediate area of

Surface disorder 5 is inserted. In the upper right area of Fig. 4 is Furthermore, the depth profile of the surface disorder 5 schematically indicated by a line L for clarity.

Corresponding electron micrographs of the same area of the exposed functional hard metal surface 2 with 150x magnification (FIG. 5) and with 1200x magnification (FIG. 6) after the above

described jet treatment with a particle beam S can be seen in FIGS. 5 and 6. The position of the previously studied

Surface disruption 5 is again characterized by encircling. In Fig. 6, the depth profile of the surface disorder 5 is also shown schematically again with a line L1.

In particular, from a comparison of Fig. 6 with Fig. 4 it can be seen that the jet treatment with the particle beam S has led to a mechanical annealing of the surface disruption 5, so that this is only extremely weak after the blast treatment. The exposed functional surface 2, which is not adjacent to the cutting edge, has consequently been blasted in the jet treatment with the particle beam S in such a way that

Microcracks and / or surface disruptions 5 were at least largely healed.

For components 1 made of hard metal or cermet are due to the

Production in a powder metallurgy process is also common

Tensile stresses in the material. In particular, remaining

Tensile stresses in a near-surface region B on an exposed functional surface 2 have a negative effect on the susceptibility to breakage and probability of failure of the component 1. By the described blast treatment of the exposed functional surface 2 with the

Particle beam S can be specifically introduced into a near-surface region B of the hard metal or cermet compressive stresses, whereby the susceptibility to breakage and the probability of failure are also reduced. The stresses can be measured with the widely used sin ² ijj method for the determination of residual stresses from lattice distortions: By choosing the beam parameters for the beam treatment with the Particle beam S, the height of the applied compressive stresses and their extent in the direction perpendicular to the surface 2 are selectively controlled, in particular by the jet pressure, the particles used in terms of size distribution, material, etc., by the angle of incidence oc, etc.

In order to preserve the advantages obtained by the jet treatment described, the exposed functional carbide or

Cermet surface 2 in the embodiment neither ground nor coated. Subsequent grinding would be associated with the risk of renewed microcracks and / or surface damage 5. Subsequent coating of the exposed functional carbide or cermet surface would reduce the compressive stresses achieved in the

Near-surface area B destroy again or at least significantly weaken.

MODIFICATIONS

Although a jet particle beam treatment S has been described with respect to the embodiment of such an exposed cemented carbide or cermet functional surface 2 which was ground prior to blasting, the advantages of which are very clear Cutting edge adjacent exposed carbide or cermet functional surfaces 2 are used, which were not ground, but were subjected to another method, for example, also for the formation of microcracks and / or surface dislocations 5 in the range of functional carbide or cermet Surface 2 can lead.

In particular, the blast treatment described above can also be used for functional hard metal or cermet surfaces 2, which have been machined before the blast treatment by electroeroding or laser machining. Even in these cases, a mechanical annealing of microcracks and / or surface distortions 5 is reliably achieved by the jet treatment with the particle beam S. According to a further modification, an exposed functional hard-metal or cermet surface 2 which is not adjacent to a cutting edge and which is in a sintered state becomes blast treatment

subjected. Under a sinter raw state is understood to mean the state of a hard metal or cermet surface, which has not undergone any mechanical processing by sintering after the production of the component 1 in a powder metallurgical production process. Also in this case any existing micro-cracks and / or surface distortions 5 can be cured reliably and it can targeted compressive stresses in the near-surface region B are introduced.

Claims

claims

Method for the mechanical annealing of functional hard metal or cermet surfaces (2),

a non-cutting-edge exposed functional hard-metal or cermet surface (2) being supported by a

Blasting with a particle beam (S) is blasted to

To heal microcracks and / or surface disruptions (5).

A method according to claim 1, wherein the blasting is carried out such that in a near-surface region (B) of the hard metal or

Cermet compressive stresses are introduced.

The method of claim 1 or 2, wherein the functional hard metal or cermet surface (2) is a contact surface for supporting the component (1) on another component, a holding surface for cooperation with a holding element or a transition surface between two such surfaces.

Method according to one of the preceding claims, wherein the functional hard metal or cermet surface (2) according to the

Blasting treatment is neither ground nor coated.

Method according to one of the preceding claims, wherein the functional hard metal or cermet surface (2) before the

Blast treatment is ground.

Blast treatment is processed by electroeroding or laser machining.

7. The method according to any one of claims 1 to 4, wherein the functional hard metal or cermet surface (2) is subjected to the blast treatment in a sintered state. 8. The method according to any one of the preceding claims, wherein the particles of the particle beam (S) glass beads and / or zirconium oxide.

9. The method according to any one of the preceding claims, wherein the particles of the particle beam (S) have a round surface structure.

10. The method according to any one of the preceding claims, wherein the

Beam treatment is carried out such that the particle beam (S) at an angle of incidence> 40 ° to the functional surface (2) is supplied.

Use of a directional particle beam on an exposed carbide or cermet non-cutting edge functional surface (2) for mechanical annealing of microcracks and / or surface dislocations (5).

Component (1) made of hard metal or cermet with one not on a

Cutting edge adjacent, exposed functional hard metal or cermet surface (2), which is irradiated for the healing of microcracks and / or surface dislocations (5) with a particle beam (S).

Component according to claim 12, wherein functional hard metal or cermet surface (2) in a near-surface region (B) has compressive stresses.

14. The component according to claim 12 or 13, wherein the functional hard metal or cermet surface (2) is ground and blasted.