The invention relates to machining tools such as milling cutters, saws, drills and the like, comprising a mother element and at least one machining surface part. The invention further relates to a method for manufacturing such tools, in particular a saw, more particularly a circular saw.

In known tools of steel the machining surface is often covered with a hard metal. However, the use of hard metal involves a number of drawbacks. The manufacture of for example a hard metal circular saw proceeds as follows. Using a laser beam a mother plate is sawn from steel, which is then automatically stretched and aligned. A tension is hereby imparted to the plate which provides it with its stability. Thereafter in an automatic hard-soldering process the parts are arranged from which the machining surfaces are created after grinding and the like. In the case of a circular saw these are the teeth. The soldering is done with silver and the mother plate and the hard metal parts which go to form the machining surface are heated for this purpose to about 650°C to bring about the solder connection between the mother plate and the hard metal parts. The above stated hard-soldering process is a precise and very expensive operation. Should something goes wrong during the process the whole product is rejected. In addition, after the soldering process the plate must be "aligned" again. Due to the heating of the periphery of the mother plate tensions have occurred in the material which must be eliminated. This elimination takes place by once again stretching and aligning, not automatically this time but manually by experts. Such experts have a "feel" for this precise operation and the quality of a circular saw depends on their expertise.

During arranging of the hard metal parts on the mother plate burn marks also occur which have to be removed

by means of sandblasting. Finally, each tooth of a circular saw blade is separately ground and checked to the correct tolerances.

The above described production process comprises many steps and is therefore time-consuming and costly. When after a period of time there occurs wear of the machining surface, re-grinding or replacement of the entire tool is necessary. This is of course also very expensive. In addition, the expertise required for the necessary alignment of the blade after soldering is also an uncertain factor in the production of such tools. In the case of illness or absence of the experts in this field the production of such tools can be subject to considerable delay.

Hard metal further contains heavy metals and both the processing thereof and the removal of the waste released during processing, or the product itself at the end of its life-span, create an impact on the environment.

It is the object of the present invention to provide a machining tool which does not have the above stated drawbacks and can be manufactured by means of a simpler production process.

The is achieved by the invention with a machining tool comprising a mother element and at least one machining surface part, wherein the machining surface part consists at least partially of glass or a ceramic material.

Surprisingly, it has been found that glass and ceramic material are sufficiently strong to be used in machining tools. In addition to window glass, different special types of glass can be used depending on the desired properties of the tool. Such special glass types include for example Duran™, C-Duran™, Sic.Duran™, Tempax™, Ceran™, Robax™, Float Glass™, and Borofloat™, all from the manufacturer Schott Glaswerke.

The advantage of the invention is that no heat treatment is required as with soldering, because the machining surface parts of glass or ceramic material can be glued onto the mother plate or other type of mother element. The manual alignment and sandblasting of the plate can

hereby also be omitted. Due to the manual "alignment" becoming superfluous the production process can be fully automated and this results in a fall in production costs.

The waste produced during production and at the end of the useful life of the end product will also have less of an impact on the environment than the conventionally used hard metal.

The invention can be applied to various types of machining tools, such as saws, in particular circular saws, milling cutters and drills. In the particularly suitable embodiment of the invention the machining tool is a circular saw, the teeth of which are embodied in glass or a ceramic material.

The invention further relates to a method for manufacturing a machining tool, comprising of manufacturing a mother element of metal, in particular steel, arranging a part or parts of glass or a ceramic material at the location of the machining surface and grinding one or more machining surfaces in the parts of glass or ceramic material. In this application "mother element" refers to the body of the tool with the exception of the machining surface. "Machining surface part" refers to the part of the tool which conventionally consists of hard metal, but which according to the invention is embodied in glass or ceramic material. In the case of manufacturing a saw, in particular a circular saw, the method according to the invention comprises of manufacturing a mother plate of metal, in particular steel, arranging parts of glass along the periphery of the mother plate and grinding teeth into the glass parts.

The parts of glass or ceramic material can be fixed for example by means of glue. On the basis of the specifications for the tool it is within the reach of the skilled person to select a glue appropriate for the material chosen for the machining surface.

The present invention will be elucidated with reference to the annexed example which is not however intended to limit the invention in any way.

EXAMPLE

A mother plate of steel for a circular saw was provided on its periphery with parts of glass. The glass parts were then ground into teeth. A circular saw manufactured in this manner was found to have sawing properties corresponding with conventional circular saws.