Process for making a diamond tool

Abstract

Disclosed is a process for making a grinding wheel for the squaring of ceramic, formed by a support body and an abrasive ring. The process does not involve costly workings on the body and on the ring and produces a light grinding wheel which, therefore, is more practical to be handled by the handling machine.

Claims

1. Process for making a diamond tool for ceramic processing, said tool comprising: a support body for fastening the tool to a machine, an abrasive layer that abrades the ceramic, an interface layer for connecting the abrasive layer to the support body, said process comprising the following steps: placing an aluminum ring-shaped support body inside a steel mold having the same shape and dimensions of the support body; placing a mixture of interface powders inside the mold and above the support body so as to obtain the interface layer of the tool; placing a mixture of abrasive powders inside the mold and above the mixture of interface powders so as to obtain the abrasive layer of the tool; putting on top under pressure the mixture of abrasive powders and, consequently, the mixture of interface powders by means of a punch; simultaneously with pressure action, heating the mold contents at a temperature between 580° C. and 650° C. for a time between 15 min. and 60 min.; in which the mixture of interface powders includes the following components (percentages by weight): i) at least 12% of aluminum powder, ii) from 0 to 2.5% of an interface powder lubricant, iii) at least one powder component selected from the following substances: copper, magnesium, silicon and zinc or mixtures thereof; and in which the mixture of abrasion powders includes the following components (percentages by weight): I) between 85% and 95% of a copper-based mixture, this mixture including the following components (percentages by weight): a) at least 50% of copper; b) less than 30% of iron; c) between 5% and 25% of tin; d) less than 20% of graphite; II) between 5% and 15% of a secondary mixture, this secondary mixture including the following components (percentages by weight): A) more than 70% of aluminum powder, B) from 0 to 2.5% of a secondary mixture lubricant, C) at least one powder component selected from the following substances: copper, magnesium, silicon and zinc or mixtures thereof.

2. Process according to claim 1, wherein the mixture of interface powders includes (percentages by weight): i) from 15% to 75%, of aluminum powder, ii) from 0.5% to 2% of the interface powder lubricant, iii) at least one powder component selected from the following substances: copper, magnesium, silicon, zinc or mixtures thereof.

3. Process according to claim 1, wherein the secondary mixture includes the following components (percentages by weight): A) from 75% of aluminum powder, B) from 0.5% to 2% of the secondary mixture lubricant, C) at least one powder component selected from the following substances: copper, magnesium, silicon, zinc or mixtures thereof.

4. Process according to claim 1, wherein the mixture of interface powders is placed inside the mold and above the support body for a thickness of 0.5-2 mm.

5. Process according to claim 1, wherein the mixture of interface powders and the mixture of abrasion powders are put under pressure and are brought at the same time at a temperature of 600° C. to 640° C. for a time between 20 and 50 minutes.

6. Process according to claim 1, wherein the secondary mixture includes: aluminum in an amount of 92.9% by weight; copper in an amount of 4.5% by weight; magnesium in an amount of 0.5% by weight; silicon in an amount of 0.6% by weight; from 1.5% of the secondary mixture lubricant.

7. Process according to claim 1, wherein the secondary mixture includes: aluminum in an amount of 96.8% by weight; copper in an amount of 0.2% by weight; magnesium in an amount of 1% by weight; silicon in an amount of 0.5% by weight; lubricant in an amount of 1.5% by weight.

8. Process according to claim 1, wherein the secondary mixture includes: aluminum in an amount of 88.3% by weight; copper in an amount of 1.7% by weight; magnesium in an amount of 2.5% by weight; zinc in an amount of 6% by weight; lubricant in an amount of 1.5% by weight.

9. Process according to claim 1, wherein the secondary mixture includes: aluminum in an amount of 80.3% by weight; copper in an amount of 2.6% by weight; magnesium in an amount of 0.6% by weight; silicon in an amount of 15% by weight; lubricant in an amount of 1.5% by weight.

10. Process according to claim 1, wherein the mixture of interface powders includes: aluminum in an amount of 65.00% by weight; copper in an amount of 32.73% by weight; magnesium in an amount of 0.35% by weight; silicon in an amount of 0.42% by weight; lubricant in an amount of 1.5% by weight.

11. Process according to claim 1, wherein the mixture of interface powders includes: aluminum in an amount of 18.00% by weight; copper in an amount of 79.4% by weight; magnesium in an amount of 0.5% by weight; silicon in an amount of 0.6% by weight; lubricant in an amount of 1.5% by weight.

12. Process according to claim 1, wherein the copper-based mixture includes (percentages by weight): from 65% to 75% of copper; from 10% to 20% of iron; from 10% to 18% of tin; from 0.5% to 1.5% of graphite.

13. Process according to claim 2, wherein the secondary mixture includes the following components (percentages by weight): D) from 75% of aluminum powder, E) from 0.5% to 2% of the secondary mixture lubricant, at least one powder component selected from the following substances: copper, magnesium, silicon, zinc or mixtures thereof.

14. Process according to claim 2, wherein the mixture of interface powders is placed inside the mold and above the support body for a thickness of 0.5-2 mm.

15. Process according to claim 3, wherein the mixture of interface powders is placed inside the mold and above the support body for a thickness of 0.5-2 mm.

16. Process according to claim 2, wherein the mixture of interface powders and the mixture of abrasion powders are put under pressure and are brought at the same time at a temperature of 600° C. to 640° C. for a time between 20 and 50 minutes.

17. Process according to claim 3, wherein the mixture of interface powders and the mixture of abrasion powders are put under pressure and are brought at the same time at a temperature of 600° C. to 640° C. for a time between 20 and 50 minutes.

18. Process according to claim 4, wherein the mixture of interface powders and the mixture of abrasion powders are put under pressure and are brought at the same time at a temperature of 600° C. to 640° C. for a time between 20 and 50 minutes.

19. Process according to claim 2, wherein the secondary mixture includes: aluminum in an amount of 92.9% by weight; copper in an amount of 4.5% by weight; magnesium in an amount of 0.5% by weight; silicon in an amount of 0.6% by weight; from 1.5% of the secondary mixture lubricant.

20. Process according to claim 3, wherein the secondary mixture includes: aluminum in an amount of 92.9% by weight; copper in an amount of 4.5% by weight; magnesium in an amount of 0.5% by weight; silicon in an amount of 0.6% by weight; from 1.5% of the secondary mixture lubricant.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Examples 1-4—Preparation of the Secondary Mixture

(1) A secondary mixture is prepared by mixing the components that will form the secondary mixture in a turbo mixer, at a speed of 23 rpm for 45 minutes.

(2) The mixing takes place at a temperature of 22° C., at atmospheric pressure without inert gas.

(3) In the following Table 1, the percentages by weight of the components of the obtained secondary mixtures are reported.

(4) TABLE-US-00001 TABLE 1 Example 1-Mix 1 2-Mix 2 3-Mix 3 4-Mix 4 % by weight of 92.9 96.8 88.3 80.3 aluminum % by weight of 4.5 0.2 1.7 2.6 copper % by weight of 0.5 1.0 2.5 0.6 magnesium % by weight of 0.6 0.5 6.0 15.0 silicon % by weight of 1.5 1.5 1.5 1.5 lubricant

Example 5—Preparation of the Mixture of Abrasion Powders

(5) A mixture of abrasion powders is prepared so as to obtain the abrasive layer by mixing, for each mixture, 10 parts by weight of the secondary mixture of Example 1 with 90 parts by weight of the copper-based mixture of known type, the copper-based mixture having the following composition (percentages by weight): 70% of copper; 15% of iron; 14% of tin; 1% of graphite.

(6) The two components forming the mixture are poured into a mixer, at first the component in greater quantity and then, the other component. The mixing is performed in an orbital mixer at a speed of 250 rpm, for 25 minutes.

(7) The mixing takes place at a temperature of 23° C., at atmospheric pressure without inert gas.

Examples 6-8—Preparation of the Mixture of Abrasion Powders

(8) The example 5 is repeated with the difference that instead of the mixture of Example 1, the mixtures of Examples 2 to 4 are utilized for each example.

Examples 9 and 10—Preparation of the Mixture of Interface Powders

(9) A mixture of interface powders (MIX A and MIX B) is prepared to obtain the interface layer and to be utilized in the embodiment of the invention described here. This mixture is obtained by mixing the mixture Mix 1 obtained in the Example 1 with an appropriate amount of copper powder. The ratios by weight as used between the two components are reported in the following Table 2.

(10) The two components forming the mixture are poured into a mixer, at first the component in greater quantity and then, the other component. The mixing is performed in a turbo mixer at a speed of 23 rpm for 45 minutes.

(11) The mixing takes place at a temperature of 22° C., at atmospheric pressure without inert gas.

(12) In the following Table 2, the percentages by weight of the components of the obtained mixtures are reported.

(13) TABLE-US-00002 TABLE 2 Example 9-Mix A 10-Mix B Mix 1 Ratio: copper 70:30 20:80 powder (by weight) Composition of the obtained mixture % by weight of aluminum 65.00 18.00 % by weight of copper 32.73 79.4 % by weight of 0.35 0.5 magnesium % by weight of silicon 0.42 0.6 % by weight of lubricant 1.5 1.5

Example 11: Sintering Processes

(14) In order to create a coupling of metallurgic/chemical type between the aluminum body and the mixture of abrasion powder (formed by the copper-based mixture with the addition of the secondary mixture) of the Example 5, a layer of 1 mm of a mixture of interface powders produced in the Example 9 is interposed.

(15) The layer of the mixture of abrasion powder has a double thickness in comparison to the final thickness, obtained at the end of the process.

(16) Then, the sintering of the mixture of abrasion powders is performed by exerting a pressure on the double layer of the mixture by means of a punch and, at the same time, the two layers are brought, together with the aluminum body itself, to a temperature of 620° C. for a time of 30 minutes.

Example 12-17—Sintering Processes

(17) The example 11 is repeated by utilizing, instead of the mixture of abrasion powder of the Example 5, the mixtures of the Examples 6 to 8 with the mixture of interface powders produced in the Example 9 or in the Example 10, respectively.

(18) All the processes according to the present invention, carried out in the examples have produced a grinding wheel with a satisfactory connection between the aluminum support body and the diamond abrasion layer although the process has been performed at a temperature lower than the temperatures usually used according to prior art.

(19) For this reason, peculiar characteristic of the invention is the use of quantities of metals capable of lowering the sintering temperature of the copper-based metal part and using a layer of powder acting as an interface for a metallurgic/chemical connection between the aluminum support body and the diamond abrasion layer.

(20) A technician of the sector can insert modifications or variants that are to be considered as included in the scope of protection of the present invention.