WO2015136331A1

WO2015136331A1 - Mulit-part tool having cooling channels and a method of aligning same

Info

Publication number: WO2015136331A1
Application number: PCT/IB2014/059799
Authority: WO
Inventors: Isak. KAKAI
Original assignee: Sandvik Intellectual Property AB
Current assignee: Sandvik Intellectual Property AB
Priority date: 2014-03-14
Filing date: 2014-03-14
Publication date: 2015-09-17
Anticipated expiration: 2016-09-14

Abstract

A method of producing a drilling or milling tool having aligned coolant channels includes the step of providing at least two sections (12, 14). Each of the sections is made of a cemented carbide or cermet. At least one first section (12) includes at least one coolant channel (24) and at least one second section (14) includes at least one coolant channel (34), wherein a diameter (ds) of the at least one coolant channel (24) of the first section (12) is larger than a diameter (df) of the at least one coolant channel of the at least one second section. The at least two sections (12,14) are fitted together and the at least one cooling channel (24) of the at least one first section (12) is aligned with the at least one cooling channel (34) of the at least one second section (14).

Description

MUL IT-PART TOOL HAVING COOLING CHANNELS

AND A METHOD OF ALIGNING SAME

TECHNICAL FIELD

The present disclosure relates to a method of producing a multi-part drilling or milling too! having better coolant low, and more particularly to a method of aligning coolant channels between at least two sections of a cemented carbide or cermet, wherein a diameter of the at least one coolant channel of the first section is larger than a diameter of the at least one coolant channel of a second section.

High wear resistant materials, such as cemented carbide, are popular for using as drilling and milling tools for wear parts. Bodies of these materials are usually made by metallurgical methods, namely, extruding or pressing followed by sintering. Such tools are popular for processing materials which are difficult to process. Cemented carbide is used for drilling and milling tools as it provides great rigidity.

However, when these tools are used for drilling or milling at high cutting speeds, the tool is subjected to great thermal stress which may lead to the drill ceasing to operate. Therefore, it is be common to cool the tool by including an enclosed coolant channel(s) running through the fluted section of the drill. Such cooling increases the service life and efficiency of the tool.

To increase the coolant flow, it is desirable to have larger coolant channels in the shank. Therefore, the two sections need to be produced separately and the then joined together. Alignment of the coolant channels is difficult and yet critical in order to maximize the cooling benefit. Therefore, an object of this disclosure is to facilitate improved accuracy in the alignment of the coolant channels.

The concept of having coolant channels with a larger diameter in the shank compared to the fluted part is known in the art as it means that there is greater tolerance for the alignment of the sections. However, there is still a need for improving the method of alignment to maximize coolant flow.

A method of alignment of coolant channels in a drill bit is known. See U.S. Patent No. 4,704,055 wherein a prism face connection is used to assist with alignment of coolant channels. However, the prism connection is not suitable for a drill blank. A conical face connection will enable more accurate alignment, especially in the situation when a sinter fuse of sintered parts is used for the joining method. SUMMARY

One object of this disclosure is to facilitate improved accuracy in the alignment of the coolant channels between the at least two sections by providing corresponding mating features on the at least one first section and the at least one second section, particularly corresponding male and female conical mating features on the ends of the two parts to be joined, as will be described further herein. Additionally, as the present disclosure will show, the introduction of the corresponding mating features achieves this need and additionally provides the advantage that the joining area has been increased thereby improving the rigidity of the joint and therefore the tool.

In another aspect of the disclosure, there is provided a method of producing a drilling or milling tool having aligned coolant channels. At least two sections are provided, each of the sections being formed of a cemented carbide or cermet. At least one first section includes at least one first coolant channel and at least one second section includes at least one second coolant channel, wherein a diameter of the at least one coolant channel of the first section is larger than a diameter of the at least one coolant channel of the at least one second section. The at least two sections are fitted together and then the at least one coolant channei(s) of the first and second sections are aligned.

In another aspect, a wear resistant tool includes at least two sections, each of the sections being formed of a cemented carbide or cermet. At least one first section includes at least one first coolant channel and at least one second section includes at least one second coolant channel, wherein a diameter of the at least one coolant channel of the first section is larger than a diameter of the at least one coolant channel of the at least one second section. The at least two sections are first fitted together and then the at least one coolant channels of the first and second sections aligned.

The foregoing summary, as well as the following detailed description of the embodiments, will be better understood when read in conjunction with the appended drawings. It should be understood that the embodiments depicted are not limited to the precise arrangements and instrumentalities shown.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a perspective view of the shank and fluted section of the wear resistant tool of the present invention. Fig. 2 is another perspective view of the shank and fluted sections.

Fig. 3 is a si de view of the shank section.

Fig, 4 is an end view of the shank section of Fig. 3.

Fig. 5 is a cross-sectional view of the shank section taken along line ΪΙ-ΙΪ of Fig. 4.

Fig. 6 is a perspective view of one end of the shank section.

Fig. 7 is a perspective view of the other end of the shank section.

Fig. 8 is a side view of the fluted section.

Fig, 9 is an end view of the fluted section of Fig. 8.

Fig. 10 is a cross-sectional view of the fluted section taken along line ΙΙΙ-ΠΙ of Fig. 9.

Fig. 11 is a perspective view of one end of the fluted section.

Fig. 12 is a perspective view of the other end of the fluted section.

Fig. 13A is a perspective view of the joined shank section and fluted section having a straight coolant channel. Fig. 13B is a cross-section of the joined sections taken along Line IV-IV of Fig. 13 A.

Fig. 14 is a cross-section of fluted section with a twisted coolant channel.

Fig. 15 A is a perspective view of the joined shank section and fluted section having a twisted coolant channel Fig. 15B is a cross-section of the joined sections taken along Line V-V of Fig. 15A.

Fig. 16 is a flow diagram of the method according to the present disclosure.

DETAILED DESCRIPTION

Referring to Figs. 1 and 2, a wear resistant tool 10, such as a drilling or milling tool can include separate sections or parts. At least two sections 12, 14 are provided, each of the sections being made of a cemented carbide or cermet. It should be appreciated that although two sections are described, a plurality of sections could comprise tool 10.

Sections 12, 14 can be made from cemented carbides or cermets of compacts of liquid phase sintered materials that include low melting phase components and high melting phase components. A cemented carbide has a hard phase composed of tungsten carbide and of one or more carbides, nitrides or carbonitrides of titanium, chromium, vanadium, tantalum, niobium bonded by a metallic phase hinder typically cobalt, nickel, iron or combinations thereof in. varying proportions. A cermet has a hard phase composed of one or more carbides, nitrides or car bonitrides of titanium, chromium, vanadium, tantalum, niobium bonded by a metallic phase typically cobalt, nickel, iron or combinations thereof in varying proportions. Sections 12, 14 can be made of the same or different cemented carbide.

In one embodiment, the at. least one first section 12 can be a straight shank, i.e., the whole of the shaft is of the same diameter, and the second at least one section 14 can be fluted, i.e., a cylindrical shaft with helical catting flutes 32 (Fig. 8). The at least two sections can be produced by known methods, for example, extrusion or pressing. It should be appreciated that although shown as a cylindrical shank, other shapes of the shank, i.e., a hex or triangle shape can be provided.

Referring to Figs. 3-7, shank 12 has opposed ends 16 and 28. End 18 of the shank section is formed with a mating feature 20. As shown in Figs. 8-12, fluted section 14 has opposed ends 26 and 28, Flute(s) 32 extend along section 14. t should be appreciated that sections 12 and 14 can be provided with a variety of different forms depending on the end use of the tool.

As shown, end 28 is formed with a corresponding mating feature 30. Referring again to Figs, 3, 5 and 7, mating feature 20 at end 18 of shank section 12 has a male conical geometry and the mating feature 30 at end 28 of fluted section 14 has a

corresponding female conical feature 30. The male and females geometries could either be as depicted as shown, i.e., with the male conical feature on the straight shank or the other way round with the male conical feature being located on the fluted section. The mating features 20 and 30 can be pre~formed in the pressing operation, machined in the green state or machined in the sintered state.

Referring again to Figs. 4 and 5, shank section 12 has at least one coolant channel 24 that is straight and extends the length thereof. Although two channels are shown, it should be appreciated that a single coolant channel, as well as a plurality of channels can be provided. Coolant channel 24 has a diameter (d_s), which will be described further herein.

Referring again to Figs. 9 and 10, fluted section 14 can have a plurality of coolant holes or channels 34 located therein. Coolant channel 34 can be straight (Fig. 13B) or twisted (Fig. 14). Moreover, the number of channels 34 is not limited.

Coolant chaimel(s) 34 have a diameter df. As shown in Fig, 13B, diameter d_s of the coolant channel 24 of shank 12 is larger than the diameter df of coolant channel 34 of fluted section. As shown in Fig. 15B, because channel 24 has a diameter d_s that is larger than the diameter df of channel 34 of the fluted section 14, when the two sections are assembled conical features 20 and 30 connect and the channels line up in an easier manner (Fig. 15A). In other words, the diameter d_s of the channel 24 has a bigger area at end 18 of the conical area. Accordingly, any slight un-alignment between channel 34 and channel 24 does not prevent the coolant flow in to the coolant channels 34 of fluted section 34 from channels 24 of the shank section. Moreover, due to the conical shape the un-alignment doesn't affect the end of the shank section that is located within the flute section. In contrast, with a different shape a quite accurate alignment would be necessary to avoid mismatch between the fluted section and shank section.

Referring to Fig. 16, the present method enables sections 12 and 14 to be assembled and the coolant channels aligned. Referring to step 36 a plurality of sections can be provided. The sections are fit together in step 38 by inserting end 18 with the conical mating feature 20 of shank section 12 into of the corresponding mating feature 30 on the end 28 of the fluted section 14. As shown in Figs, 5 and 10, shank section 12 has an outer diameter d[ and fluted section 14 has an outer diameter d₂. Diameters (d|, d₂) of the sections may be the same or of a different size. Accordingly, if different sized sections are be assembled the widths and positions of the coolant channels can be adjusted without affecting the coolant channels alignment due to the mating features 20, 30.

After the at least first and second sections are fitted together, the coolant channels in the different sections are aligned in step 40. As set forth above, because channel 24 has a diameter d_s that is larger than the diameter d_f of channel 34 of the fluted section 14, when the two sections are fitted together conical features 20 and 30 connect and the channels line up. Hence, the bigger area of diameter d_s of the channel 24 accommodates any slight un- alignment between channel 34 and channel 24 and coolant flow into the coolant channels 34 of fluted section 14 from channels 24 of the shank section is not prevented. Moreover, due to the conical shape the un-alignment doesn't affect the end of the shank section that is located within the flute section.

After fitting and aligning the sections, the at least two sections are joined in step 42 by brazing, welding, soldering, direct pressing, shrink, fitting, co-sintering two green sections or sinter fusing two sintered sections. In one embodiment, the joining method could be joining together at least two sintered sections by subjecting them a vacuum or gas atmosphere without the application of external pressure, and to a temperature sufficient to fuse the at least two sections together at a bonding interface 22 (Figs. 3 A and 15A) to form a unitary body, which provides the advantages of achieving a cost effective joining method where no additional material need to be added and without resulting in grain growth at the interface. The unitary body is defined as a singular integral body. For example, the sintered sections are fused at a temperature low enough so that minimal grain growth occurs. For example, of about 1340°C to about 136Q°C for about 10 to about 30 minutes, and more preferable about 1350°C for about 15 minutes. In other words, the parts are fused at a temperature lower than or intermediate to the melting point of the material having the lowest original sintering temperature of the parts. This lower temperature and shorter time enables the fusing to proceed by short range diffusion of the binder metals across the interface and minimal grain size changes are induced in the microstructures. When the at least two sections are joined together using a sintering method it is preferably to sinter the sections together at a tray angle of 45-60°.

The present methodology offers many advantages, included but not limited to, significant cost savings by enabling ease of production. Key advantages also include alignment of coolant channels of sections not possible by conventional processing or machining. Also material combinations not possible by current methods can be achieved.

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred therefore, that the present disclosure be limited not by the specifies disclosed herein, but only by the appended claims.

Claims

1. A method of producing a drilling or milling tool ( 0) having aligned coolant channels, the method comprising the steps of:

providing at least two sections (12, 14), each of the sections being formed of a cemented carbide or cermet; at least one first section (12) including at least one first coolant channel (24) and at least one second section (14) including at least one second coolant channel (34), wherein a diameter (d_s) of the at least one coolant channel (24) of the first section (12) is larger than a diameter (df) of the at least one coolant channel (34) of the at least one second section (12);

fitting together the at least one first section (12) and the at least one second section(14); and

aligning the at least one coolant channel (24) of the at least first section (12) and the at least one cooling channel (34) of the at least second section. 2. The method according to claim 1 , characterized in that the at least one first section (12) and the at least second section (14) are made of the same or different cemented carbide or cermet.

3. The method according to any of the preceding claims, characterized in that the at least one first section (12) is a straight shank and the at least one second section (14) is fluted.

4. The method according to any of the preceding claims, characterized in that each of the at least one first section (12) and the at least second section (14) have the same or different diameter (di, d₂).

5. The method according to any of the preceding claims, characterized in that the at least one first section and the at least second section are produced by extrusion or pressing.

6. The method according to any of the preceding claims, further comprising the step of sintering the at least one first section and the at least second sections prior to fitting and aligning.

7. The method according to any of the preceding claims, characterized in that an end (18) of the at least one first section (12) is formed with a mating feature (20) and an end (28) of the at least one second section (14) is formed with a corresponding mating feature (30).

8. The method according to claim 7, characterized in that the mating feature at the end of the at least one first section (12) has a male conical geometry and the mating feature at the end of the at least one second section (14) has a corresponding female conical geometry

9. The method according to claim 7, characterized in that the mating feature at the end of the at least one first section (12) has a female conical geometry and the mating feature at the end of the at least one second section (14) has a corresponding male conical geometry.

10. The method according to claim 8 or claim 9, characterized in that the male and female conical ends (20, 30) are pre-formed in a pressing operation, machined in a green state or machined in a sintered state.

11. The method according to any of the preceding claims, further comprising the step of joining the at least one first section (12) and the at least one second section (14).

12. The method according to claim 11 , characterized in that the at least one first section (12) and the at least one second section (14)are joined by brazing, welding, soldering, direct pressing, shrink fitting, co-sintering two green sections or sinter fusing.

13. The method according to any of the preceding claims, characterized in that the at least one first section (12) and the at least second section (14) are sintered and a step of joining the sintered the at least one first section (32) and the at least second section (14) comprises subjecting them to a vacuum or gas atmosphere, without the application of external pressure, and to a temperature sufficient to fuse the at least two sintered sections together at a bonding interface (22) to form a unitary body.

14. The method according to any of the preceding claims, characterized in that the at least one coolant channel (24) of the at least one first section (12) is a straight coolant channel and the at least one coolant channel of the at least one second section is at least one twisted or straight coolant channel.

15. A drilling or milling tool or a wear resistant tool made according to the method of any of claims 1-14.

16. A wear resistant tool comprising:

at least one first section (12) formed of a cemented carbide or cermet, the at least one first section having at least one coolant channel (24); and

at least one second section (14) formed of a cemented carbide or cermet, the at least one second section (14) having at least one coolant channel (34), characterized in that the at least one coolant channel (24) of the at least first section has a diameter (d₅) larger than a diameter (d_f) of the at least one coolant channel (34) of the at least one second section (14) and wherein when the at the at least one first section and the at least one second section are fitted together the coolant channels are aligned.

17. The wear resistant tool according to claim 16, characterized in that eac of the at least one first section and the at least one second section is made of the same or different cemented carbide.

18. The wear resistant tool according to claim 16 or 17, characterized in that the at least one first section (12) is a straight shank and the at least one second section (14) is fluted (32). 9. The wear resistant tool according to any of claims 16-18, characterized in that the at least one first section (12) is fluted and the at least one second section (14) is a straight shank.

20. The wear resistant tool according to any of claims 16-19, characterized in that each of the at least one first section and the at least second section has the same or different diameter (di, d₂).

21. The wear resistant tool according to any of claims 16-20, characterized in that the at least first section and the at least second section are produced by extrusion or pressing. 22. ^'The wear resistant tool according to any of the claims 16-21, characterized in that an end (18) of the at least one first section (12) is formed with a mating feature (20) and an end (28) of the at least one second section (14) is formed with a corresponding mating feature (30). 23. The wear resistant tool according to claim 22, characterized in that the mating feature (20) at the end (1 8) of the at least one first section (12) has a male conical geometry and the mating feature (30) at the end (28) of the at least one second section (14) has a corresponding female conical geometry. 24. The wear resistant tool according to claim 22, characterized in that mating feature at the end of the at least one first section (12) has a female conical geometry and the mating feature at the end of the at. least one second section (14) has a corresponding male conical geometry. 25. The wear resistant tool according to claim 23 or claim 24, characterized in that the male and female conical ends are pre-formed in a pressing operation, machined in a green state or machined in a sintered state.

26. The wear resistant tool according to any of claims 6-25, characterized in that the at least first section and the at least second section are sintered parts are joined by subjecting them to a vacuum or gas atmosphere, without the application of external pressure, and to a temperature sufficient to fuse the sections together at the bonding interface to form a unitary body. 27. The wear resistant tool according to any of claims 16-26, characterized in that the a least one coolant channel (24) of the at least one first section (12) is a straight coolant channel and the at least one coolant channel (34) of the at least one second section (14) is at least one twisted or straight coolant channel.

28. The wear resistant tool according to any of claim 16-27, characterized in that the tool is a drilling or milling tool.