METHOD OF ATTACHING SEGMENTS TO CUTTING TOOL

Abstract: A method of attaching segments to the body of a cutting tool, such as a diamond saw blade, is initiated by inseparably coupling the segments to their respective interposed mem­ bers by sintering. The interposed members are made of iron, cobalt, or other metal. Then, the interposed members are rigidly coupled to the body by welding or other method.

Description: FIELD OF THE INVENTION The present invention relates according to the preamble of claim 1 to a cutting tool such as a diamond saw blade, diamond core bit, or diamond gang saw blade; see US-A 3 162 187. BACKGROUND OF THE INVENTION Generally, the body of a cutting tool, such as a diamond saw blade, is made of iron, and segments which consist of a bronze alloy, an alloy of cobalt, copper, and other elements, or a tungsten alloy and to which diamond dust is added are rigidily attached to the ends of the body by brazing, laser welding, sintering, or other similar means. However, where segments are attached by brazing, heat is generated due to friction when the cutting tool is in use. This softens the locations at which the segments are attached. As a result, the segments may disengage from the body. Where segments are attached by laser welding, cracking often takes place near the weld zones immediately after the welding operation, making the segments useless. Where segments are attached by sintering, if the body has been quenched, the heating during sintering releases the stress remaining in the body, thereby producing thermal stress. This may lower the cutting accuracy. Accordingly, the material of the body must be selected from limited number of substances. This may increase the cost to fabricate the body. SUMMARY OF THE INVENTION Accordingly, it is the object of the present invention to provide a cutting tool, being free of the foregoing difficulties. Specifically, according to the invention as claimed in claim 1, the segments are prevented from becoming damaged while the tool is in use. Further, the segments do not disengage from the body. In addition, the tool is economical to manufacture. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front elevation of a saw blade embodying the present invention; Fig. 2 is a cross-sectional view taken along the line II-II of Fig. 1; Fig. 3 is a fragmentary, exploded perspective view of the saw blade of Fig. 1, for showing the manner in which one segment is attached to the body; Fig. 4 is a cross-sectional view of another support ridge and another groove into which the ridge is fitted; Fig. 5(A) and 5(B) are fragmentary, exploded perspective view of saw blades, for showing other installation surfaces to which segments are attached; Fig. 6 is a cross-sectional view showing a further interposed member and a segment; and Fig. 7 is a view similar to Fig. 3, but showing a still other interposed member. DETAILED DESCRIPTION OF THE INVENTION Referring to Figs. 1, 2, and 3, there is shown a diamond saw blade. The body of this blade is indicated by numeral 1, and takes a disklike form. The body 1 is made of iron and has been quenched. A plurality of notches 2 are equally or arbitrarily spaced apart from each other circumferentially in the outer periphery of the body 1. An installation portion 3 to which an interposed member 4 is attached is formed between each two successive notches 2. Each interposed member 4 is inseparably mounted to the outer periphery of each installation portion 3 by inert-gas tungsten arc welding or laser welding. As best shown in Fig. 3, each interposed member 4 is composed of a slender plate 4a for rigid mounting and a support ridge 5 formed integrally with the plate 4a and extending on the outer surface of the plate 4a over its whole length. The plate 4a is curved so as to correspond to the arc-shaped outer fringe of the installation portion 3 of the body 1. A pair of first installation surfaces 6 is formed on each side of the ridge 5 on the outer surface of the plate 4a. A pair of second installation surfaces 7 is formed on each side surface of the ridge 5. A third installation surface 8 is formed on the top, outer surface of the ridge 5. Each interposed member 4 is made of iron, cobalt, manganese, chronium, nickel, brass, copper, or other material. The installation surfaces 6, 7, 8 are all finished roughly. Segments 9 are firmly attached to the outer side surface of each interposed member 4. As can be seen from Fig. 2, each segment 9 is made somewhat thicker than the body 1, and is provided with a groove 10 extending on the inner side of the segment 9 over the whole length of the segment. The groove 10 is so dimensioned that the protrusion 5 of each interposed member 4 is fitted into it. Each segment 9 is made of a bronze alloy, an alloy of cobalt, copper, and other elements, a tungsten alloy, or other alloy. Diamond dust has been added to the material which has been sintered. Sufficient hardness is imparted to each segment 9 to prevent it from becoming chipped while it is being machined. The manner in which each segment 9 is attached to the body 1 is now described. First, diamond dust is added to powdered metal or metal compound. Then, this mixture is sintered to form each segment 9. During this sintering operation, one interposed member 4 which has been already formed is placed in contact with the inner side surface of each segment 9 to inseparably mount the segment 9 to the interposed member 4 in such a way that the support ridge 5 of the member 4 is fitted in the groove 10 in the segment 9. The temperature at which the powdered metal or metal compound is heated during the sintering operation varies from material to material. When the material is a bronze alloy, the temperature is approximately 650°C. When it is a cobalt alloy, the temperature ranges from about 750°C to 800°C. When it is a tungsten alloy, the temperature is roughly equal to 1040°C. After mounting the segments 9 to the interposed members 4 as described above, the inner side surface of each member 4 is rigidly fixed to the outer periphery of the body 1 by inert-gas tungsten arc welding, inert gas arc welding using a consumable electrode, laser welding, or other process. In this diamond saw blade, the segments 9 are fastened to the interposed members 4 by sintering and then the members 4 are welded to the body 1. Therefore, it is unlikely that the stress remaining inside of the body 1 is released by the heating during sintering, thereby deforming the body 1. Also, since the segments 9 are not directly attached to the body 1, cracking does not take place in heat-affected zones in the segments 9. In addition, since the segments 9 are joined to the interposed member 4 by sintering, there exists no possibility that the joined portions are molten by the heat produced when the saw blade is in use. Consequently, the segments 9 are prevented from coming off the interposed members 4. Furthermore, as the installation surfaces 6-8 on the interposed members 4 are made rough , these surfaces are in contact with the segments 9 with increased area of contact. This ensures that the segments 9 are rigidly joined to the interposed members 4 by means of sintering. The sintering is done after the support ridge 5 of each interposed member 4 has been fitted in the groove 10 of each segment 9 and so the segments 9 are rigidly coupled to the interposed members 4. It is to be understood that the present invention is not limited to the above-mentioned embodiment, but rather various modifications and changes may be made without departing from the spirit and scope of the invention as claimed. (1) Referring to Fig. 4, each support ridge 5 of the interposed members 4 may be shaped into a dovetailed form in cross section and each groove 10 of the segment 9 may be shaped into the corresponding form in cross section so that the segments 9 may be more rigidly fastened to the interposed members 4. (2) At least one of the three kinds of installation surfaces 6, 7, and 8 of the interposed members 4 may be knurled, as shown in Fig. 5(A), or serrated, as shown in Fig. 5(B). Also, the surfaces of the segments 9 with which the machined ones of the installation surfaces 6-8 make contact may be knurled or serrated. (3) Referring to Fig. 6, the support ridge 5 of the interposed members 4 may be omitted. Instead, the outer surface of each plate 4a for rigid coupling may be serrated to form an installation surface 6a. Also, each groove 10 in the segments 9 may be omitted, and the inner side surface may be serrated. This ensures sintering and facilitates the manufacture of the interposed members 4. (4) Referring to Fig. 7, each interposed member 4 may be shaped into a simple rectangular pillar so that the whole member 4 can be received in the groove 10 in each segment 9. This contributes to simplification of the structure. (5) Each segment 9 may be previously formed by sintering. Then, the segments 9 may be coupled to the interposed members 4 by sintering. (6) The invention is not limited to diamond saw blades, but rather it may also be applied to other diamond cutting tools, such as diamond core bits, or diamond gang saw blades, or to segments for carbide tools other than diamond cutting tools. As described in detail thus far, the present invention prevents the body of a saw blade or the like from being deformed when segments are mounted to it. Also, it is unlikely that the segments come off the body or become damaged when the blade is in use. Further, the blade is relatively cheap to manufacture.

Claims: A cutting tool comprising a supporting body (1) and cutting segments (9) disposed on installation locations on the supporting body (1), characterized in that for each installation location an associated interposed member (4) is provided having a plate (4a) and a ridge (5) and further a plurality of roughened installation surfaces (6, 7, 8), whereby each segment (9) is sintered to an associated interposed member (4) along each of said installation surfaces (6, 7, 8) such that the segments (9) are disposed separately from the supporting body (1) through the plates (4a), and that after said sintering each interposed member being welded to its associated installation location such that only a bottom surface of the plate (4a) contacts the installation location. A cutting tool according to claim 1, characterized in that each of the installation surfaces (6, 7, 8) is roughened. A cutting tool according to claim 1 or 2, characterized in that at least one of the installation surfaces (6, 7, 8) of the interposed members (4) is knurled. A cutting tool according to claim 1 or 2, characterized in that at least one of the installation surfaces (6, 7, 8) of the interposed members (4) is serrated. A cutting tool according to claim 1 or 2, characterized in that the support ridge (5) is of dovetailed-shaped section and a groove (10) in each segment (9) has a corresponding section. A cutting tool according to claim 1, characterized in that the outer surface of each plate (4a) and the inner surface of each segment (9) are serrated to form an installation surface (6a).

Inventors: OMI, SHOHEI
Applicants: OMI KOGYO CO., LTD.
Application year: 1985
Main classification: B23D65
IPC codes: B28D1, B24D5, B23D65