GB2066857A

GB2066857A - >Method for the production of an abrasive surface

Info

Publication number: GB2066857A
Application number: GB8000385A
Authority: GB
Original assignee: Vmei Lenin
Current assignee: Vmei Lenin
Priority date: 1980-01-07
Filing date: 1980-01-07
Publication date: 1981-07-15

Abstract

A method for the production of an abrasive surface is provided, the method involving a simultaneous deposition onto the surface of both a chemically derived nickel coating and abrasive particles, which particles are brought into a contact with the said surface by means of an agitator, after which the abrasive coating thus obtained is submitted to an additional hardening step by nickel plating the surface in another, separate bath for chemical nickelling.

Description

SPECIFICATION Method for the production of an abrasive surface This invention relates to a method for the production of an abrasive surface, especially for tools having an active surface with particles of a high hardness included in it, which tools are suitable for the grinding of machinery parts.

Methods for production of abrasive tools are known in which a metal plating with abrasive particles included therein is deposited onto the active surface of the tool. Generally the metal of the plated coating is nickel and the abrasive particles bort or cubic phase boron nitride.

The main disadvantage of these methods is that the metal is not distributed uniformly over the active surface of the tool, and is due to the character of the technology of plating, which results in a poor distribution of the abrasive particles over the surface of the tool; moreover, the metal of the plated coating lacks hardness, firmness and wear resistance; the devices for accomplishing these methods are complex; and it takes a long time to produce the abrasive coating.

Also, methods are known for chemical (no electrical current) deposition of disperse coatings, wherein particles of size less than 5 microns are built into a metal coating. By these methods, particles of for example silicon dioxide, titania and corundum are incorporated into the metal coating thereby achieving enhanced wear resistance and hardness, but this does not provide the cutting properties which are required for abrasive tools.

An object of this invention is to provide a method for the production of abrasive tools which ensures precision, uniformity and wear resistance of the abrasive coating obtained while the method can be performed with relatively simple apparatus.

According to the present invention, there is provided a method for the production of an abrasive surface, e.g. for a tool, in which an abrasive coating is deposited onto the surface, which method comprises forming the abrasive surface by a simultaneous deposition onto the surface of both a chemically derived nickel coating and abrasive particles, which particles are brought into a contact with the said surface by means of an agitator, after which the abrasive coating thus obtained is submitted to an additional hardening step by nickel plating the surface in another, separate bath for chemical nickelling. Preferably, the abrasive particles are brought into contact with the surface at regular intervals. Agitation can be effected intermittently, each active phase lasting 0.5 to 4 minutes and being followed by a rest phase of from 3 to 15 minutes.

Advantageously, the agitation is effected by rotating an agitator at a rate of 200 to 400 cycles per minute, preferably at about 300 cycle per minute. Generally, the deposition of the abrasive coating will be effected using a bath at a temperature in the range of from 55"C to 95"C. The chemical nickel coating may be deposited from a hypophosphite or dimethylamine borane work solution. The abrasive material (particles) can consist of bort, cubic boron nitride, boron carbide, or mixtures of two or more of these materials. The abrasive particles are preferably from 20to 120 microns in size.

Using the method of the invention, it may be possible to obtain a coating which is uniform both in thickness and content of abrasive particles, while possessing both a high hardness and wear resistance; to reduce the time required for producing the abrasive coating in comparison to prior art methods; and the apparatus needed for implementing the method is simple in design. The method allows a significant reduction of the non-effective consumption of abrasive material.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is an example of an apparatus for carrying out the method and the invention to produce an abrasive tool; Figure 2 shows a workpiece in the form of a flat disc tool; and Figure 3 shows another workpiece in the form of a pin for internal grinding together with views of a multisocketfacility in which the pins are fixed.

The apparatus shown in Figure 1 consists of a work bath with jacketed walls 4 and eiectric heaters 5 which heat the heat carrier 6 which transmits heat to the solution for the chemical nickelling through solution 7. The working temperature of the solution is maintained by means of a thermometer 8 and temperature control device 9. The solution is agitated at regular intervals by a rotating blade agitator 10 controlled by a clock relay 11. As shown in Figure 1, the treatment bath includes a flat disc tool 1 and a socket tool 3 which is adapted to receive a plurality of pins 2. These tools are shown in detail in Figures 2 and 3.

The invention will now be further illustrated by the following Examples.

Example 1 In the production of the abrasive flat disc tool which is applicable in machines for treatment of tobacco and cigarettes, a low carbon constructional steel is used as the base material for the workpiece. After initial machining, the workpiece is submitted to a photochemical treatment in order to obtain uniformly distributed over the acting surface spots covered with a photolacquer, which spots are of appropriate form. The abrasive coating is to be deposited over these spots.A hypophosphite solution intended for chemical nickelling is prepared in accordance with the following composition: nickelous sulphate (septahydrate) - 18.7 g/l ammonium fluoride - 1.1 g/l sodium hypophosphite (monohydrate) - 15.5 g/l sodium acetate (trihydrate) - 14.0 g/l malic acid (99%) - 8.0 girl lead dichloride - 1.5 mg/l sodium dodecyl benzene sulphonate - 5.0 mg/l The work solution is poured into the work bath 4 and is heated to a temperature of 90"C.

The workpieces for the tool 1 are cleaned, degreased and activated through a five-minute immersion in a 20% solution of hydrochloric acid. The workpieces so treated are placed onto the bottom of the work bath 4 which is filled up with the work solution 7, and are nickelled for 5 minutes.

Rotating the agitator at 300 cycles per minute, a synthetic diamond dust is added to the solution for chemical nickelling while the agitator performes a regime composed of 2 minutes of active agitation and 4 minutes rest time. After 80-minutes of this treatment, the workpieces are removed from the bath and are rinsed with tap water. Thereafter, the preventive photolacquer is removed and the workpieces are placed in another bath for chemical nickelling, said bath containing a work solution having the above composition, wherein they are nickel led for a further time of 90 minutes at a temperature of 90into obtain the finished abrasive tools. The abrasive material used can alternatively be cubic boron nitride, or a mixture of a synthetic diamond and boron carbide.

Example 2 The procedure of Example 1 is repeated with the exception that the dust is of natural diamond, and the solution for chemical nickelling contains: nickelous acetate - 46 g/l nickelous citrate - 24 g/l lactic acid - 20 g/l dimethylamine borane - 2.6 g/l dithioglycolicacid - 0.11 girl The pH of the solution is 5.2 and the work temperature is 65"C, while the regime of the agitator consists of 2 minutes agitation at 200 cycles/min and of 6 minutes rest time.

Example 3 For the production of an abrasive tool pin for internal grinding of machinery parts, the solution for chemical nickelling indicated in Example 1 is used. After cleaning, degreasing and activating of the surface of the workpieces as in Example 1, they are arranged into the multisocket facility 3. The facility 3 is placed onto the bottom of the work bath which is filled up with the work solution of Example 1, but at a temperature of 92"C. After a time of 3 minutes, synthetic diamond dust is added into the solution at a mass ratio which is 3 times greater than the nickel content of the solution. The agitator performs a regime of 3 minutes of agitation at 200 cycles/min followed by 4 minutes rest time. After each interval of 21 minutes, the facility 3 is rotated through an angle of 72". After a total time of 105 minutes, the facility 3 is removed from the solution, rinsed with tap water and placed in another bath containing a solution for chemical nickelling with the same composition as the solution used in Example 1, the temperature of the solution being 90 C and, there being no abrasive dust included therein. The pins are nickelled for an additional time of 100 minutes till the final abrasive tool is obtained.

Claims

1. A method for the production of an abrasive surface, e.g. for a tool, in which an abrasive coating is deposited onto the surface, which method comprises forming the abrasive surface by a simultaneous deposition onto the surface of both a chemically derived nickel coating and abrasive particles, which particles are brought into a contact with the said surface by means of an agitator, after which the abrasive coating thus obtained is submitted to an additional hardening step by nickel plating the surface in another, separate bath for chemical nickelling.

2. A method according to claim 1, wherein the abrasive particles are brought into contact with the surface at regular intervals.

3. A method according to claim 2, wherein agitation is effected intermittently, each active phase lasting for 0.5 to 4 minutes and being followed at a rest phase of from 3 to 15 minutes.

4. A method according to claim 1, 2 or 3, wherein the agitation is effected by a rotary agitator which is rotated at from 200 to 400 cycles per minute.

5. A method according to claim 4, wherein the agitator is rotated at from 200 to 300 cycles per minute.

6. A method according to any preceding claim, wherein the nickel coating is deposited from a hypophosphite work solution.

7. A method according to any one of claims 1 to 5, wherein the nickel coating is deposited from a dimethylamine borane work solution.

8. A method according to any preceding claim, wherein the abrasive particles comprise bort.

9. A method according to any preceding claim, wherein the abrasive particles comprise cubic boron nitride.

10. A method according to any preceding claim, wherein the abrasive particles comprise boron carbide.

11. A method according to any one of claims 1 to 7, wherein the abrasive particles consist of a mixture of bort, cubic boron nitride and boron carbide.

12. A method according to any preceding claim, wherein the abrasive particles are from 20 to 120 microns in size.

13. A method according to any preceding claim, wherein the deposition of the abrasive coating is effected using a bath at a temperature in the range from 55"C to 95"C.

14. A method for the production of an abrasive surface, substantially as described in any one of the foregoing examples.

15. A body bearing an abrasive surface which has been produced by a method as claimed in any preceding claim.

16. A body as claimed in claim 15, which is an abrasive tool.