The present invention relates to a manufacturing process for a diamond saw which is capable of cutting at a high speed various articles such as gems, ferrites, stones, ceramics and the like. Background of the invention

Diamond saw is classified into two kinds, and one of them is manufactured by electro-depositing diamond powders on the surface of a steel sheet, while the other of them is manufactured by applying the metal bonding method. More specifically, the latter is manufactured in such a manne*- that: diamond powders and metal alloy powders are mixed together in a certain ratio; the mixture is out. into a cold rolling mould in order to carry out a high pressure molding; a sintering is carried out at a temperature of 800 - 900°C; and then, a dressing is carried out so as for the diamond powders to be projected. Further metal alloy powders used in the metal bonding method include ccpper- base alloy or cobalt-base alloy powders. The above described electro-deposi ed or metal bonding type saws are also classified into circular saws and band type saws depending on their shapes. T e αiamonc saws which are manufactured by electro-depositing diamond powders on the surface of a steel sheet are somewhat fast

in their cutting speed, and precise in their cutting quality, but their life expectancy is very short. These saws are used to cut low strength articles and gems. The metal bonding type saws are mostly large saws and are used to cut stones, concretes and the like.

Therefore, such conventional diamond saws have to be selectively used depending on the objects to be cut, such as gems, ferrites, semiconductors, glasses, ceramics, stones and the like, such a proper selection of the saw being a troublesome task.

Further, the saw blade is very thick, and therefore, when an article is cut, the material loss is very large. Further, due to the large thickness of the saw blade, the contacting surface between the saw blade and the object to be cut is very large in the relative terms so as for the cutting load to be very large, thereby making it impossible to cut at a high speed, and deteriorating the work efficiency and the productivity. Summary of the invention The present invention is intendec to overcome the above described disadvantages of the conventional diamond saws. Therefore it is an object of the present invention to provide a diamond saw in which onl two tyoes having only different sizes are mass-produced, and the thickness of the saw blade is kept to the minimum, so that the diamond saw can be universally applied, and that the life expect¬ ancy of the saw should be extended.

It is another object of the present invention to provide a diamond saw in which the material loss is minimized and the productivity is improved by applying the universally usable and thin blade diamond saw in cutting various articles.

In achieving the above objects, the diamond saw according to the present invention is manufactured in such a manner that: an adhesive is spread on a steel sheet; diamond powders with or without metal coating are uniformly spread; it is put into a mould; and a heating at a high pressure is carried out so as for the diamond particles to be buried into the semi-melted steel sheet. When the diamond powers are buried sufficiently into the steel sheet, it is cooled so that the steel sheet should securely hold the diamond particles owing to the contracting phenomenon occurring during the cooling, thereby making the diamond particles buried firmly into the steel sheet. Brief description of the drawings

The above object and other advantages of the present invention will become more apparent by describing in detail the preferred embodiment of the present invention with reference to the attached drawings in which: Figure 1 is a longitudinal sectional view showing the pressed state of the mould used in tne manufactur ^e ng process according to the present invention; Figure 2 is a longitudinal sectional view showing anothe*" embodiment of the pressing of the mould used in tne manu-

facturing process according to the present invention: and -igure 3 is a longitudinal sectional view of the diamond- saw manufactured according to the process of the present invention. Description of the preferreα embodiment Example 1

Liquid paraffine 7 is thinly spread on the surface of a saw blade portion 2 of a saw 1; diamond powders 3,3' with metal coating are uniformly spread thereupon; the saw blade portion 2 is placed into forming recesses 5,5' of mutually facing moulds 4,4'; the mutually facing moulds 4,4' are mutually pressed; under a high vacuum, a heating is carried out using a high-frequency furnace to heat to a temperature of 870 - 1200°C for 1- 30 seconds the portions of the moulds 4,4' where the saw blade portion 2 is placed; and in this state, upon arriving of a semi-melted state between the solidus line and the liquiduε line, about three-fourths of the particles of the diamond pow¬ ders 3,3' are buried into the steel sheet of the saw blade portion 2, here the liquid paraffine being burnt off by the high temperature.

When the diamond particles are sufficiently buried into the steel sheet, the heating is stopped, and cooled in a pressed state to the normal temperature. Under this condition, owing to the contracting phenomenon during the cooling, the diamond particles are firmly held in the steel sheet, and in this state, if the mould 4,4' are

separated, a finished product 6 can be obtained.

Example 2

Liquid paraffine 7 is thinly spread on the surface 5,5' of the molding recesses 5,5' of the moulds 4,4' where the saw blade portion 2 of the saw 1 is to be placed; diamond powders 3,3'without metal coating are uniformly spread thereupon; the saw blade portion 2 of the saw is placed into the molding recesses 5,5' of the mutually facing moulds 4,4'; the mutually facing moulds 4,4' are mutually pressed; in an atmosphere consisting of a reduction gas, a heating is carried out using a high-frequency furnace to heat to a temperature of 870 - 1200°C for 1 - 30 seconds the portions of the moulds 4,4' where the saw blade por¬ tion 2 is placed; and in this state, upon arriving of a semi-melted state between the solidus line and the liqui- duε line, about three-fourth of the particles of the diamond powders 3,3' are buried into the steel sheet o~ the saw blade portion 2, here the adhesive 7 being burnt off by the high temperature.

When the diamond particles are sufficiently buried into the steel sheet, the heating is stopped, and a cooling is carried out in a pressed state until the normal tempera¬ ture is attained. Thus, owing to the contracting phe¬ nomenon occurring outing the cooling, tne diamond particles are firmly buried into the steel sheet, and in this state, if the moulds 4,4' are separatee, a finished product 6 is obtained. In the diamond saw manufactured according t,o the above

described embodiments of the present invention, there are no detachments of the particles because the diamond particles are firmly buried into the steel sheet owing to the contracting phenomenon occurring during the cooling. Further, the saw blade portion 2 which press-formed in the molding recesses 5,5' by pressing the moulds 5,5' has a uniform thickness, and also its surface state is very uniform, so that there should be required no additional finishing work, and that the product can be αirectly used. As the material for the moulds 4,4' cf the present inven¬ tion, a ceramic, a carbon or a heat resistant steel can be used. As the adhesive for securing the diamond pow¬ ders, paraffine, PVA, CMC, sodium alginate and the like having adhesive property can be used. When a solution of these materials is spreaded on the surfaces of the molding recesses 5,5' of the moulds 4,4', the solvent has to be completely removed by raising the temperature after spreading the diamond powders 3,3'. The diamond powders can be used mixed with alloyed metal powders in a proper ratio, and depending on the selected material of the moulds 4,4', an electric arc may be used in place of the high frequency.

The diamond saw according to the present inventicr is classified into two kinds according to the type of the application. Of the two kinds, the diamond saw which is for cutting gems and uses the particle size of 325 - 400 meshes can be manufactured down to the thickness of 0.07mm

(c ^* . the conventional electro-deposited saw: 0.45 - 0.5 mm), while the diamond saw which is for cutting stones and uses the particle size of 30 - 45 meshes can be manufac¬ tured down to the thickness of 1.5 mm (cf. the convention- al metal saw: 11 mm). Therefore, the diamond saw accord¬ ing to the present invention can be manufactured in a thickness equivalent to 1/7 that of the conventional electro-deposition or metal bonding saws. According to the present invention as described above, the adhesion between the diamond powders and the steel sheet is very firm, and the attainable thickness is very thin.

Therefore, the material loss can be inhibited, and the productivity can be improved by increasing the cutting efficiency.