JP2008044070A - Honing grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a honing grinding wheel with a super-abrasive metal bonded grinding wheel and without a truing operation at an initial stage of mounting to a honing tool. <P>SOLUTION: A square-pole-like grinding wheel 5 is integrally jointed to a grinding wheel platform 6, and the grinding wheel 5 is a super-abrasive metal bonded grinding wheel obtained by bonding super-abrasives such as fine diamond abrasives and CBN abrasives by a metal bonding material. A grinding wheel surface portion of the super-abrasive metal bonded grinding wheel 5 is formed of a fragile grinding wheel layer 7 having multiple indented and projected surfaces. Thereby, by mounting a subject workpiece to a honing tool of a honing machine and honing it, the portion of the fragile grinding wheel layer 7 is abraded and dropped generally by a first honing processing, and the grinding wheel face 5a is entirely brought into contact with an inside diameter face of a processed hole of the workpiece. As a result, the grinding wheel face 5a is formed into a round shape along the inside diameter face of the processed hole. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a honing grindstone, and more particularly to a structure technology of a honing grindstone that is replaceably attached to a honing tool of a honing machine.

  In the honing process, for example, a fine grindstone is used for the purpose of further smoothing the inner surface of a workpiece (hereinafter referred to as a workpiece) finished by precision boring, grinding, etc., and improving the processing accuracy of the inner surface. It is a finishing method in which the inner surface of the workpiece is brought into surface contact and lightly ground, and is one of the precision finishing methods that can produce the best workpiece surface together with lapping and super finishing.

  There is a honing machine as a dedicated machine tool for performing this honing process, and its general basic structure is equipped with a honing tool that holds one to several honing stones. The workpiece surface is machined while applying a predetermined pressure to the honing grindstone and simultaneously pouring a large amount of machining fluid.

  By the way, the honing grindstone is configured to be exchangeably attached to the honing tool, and the general basic structure thereof is that the grindstone b is integrally formed on the upper surface of the grindstone base a as shown in FIG. Bonded and fixed. The honing grindstone G is detachably mounted on the grindstone groove d of the mandrel c of the honing tool in the honing machine. e indicates an expansion rod that expands (cuts) the honing grindstone G radially outward, and f indicates a guide that guides the honing grindstone G within the hole to be machined.

  And although not specifically shown, the driving of the honing machine causes the mandrel c of the honing tool to be inserted into the hole to be processed of the workpiece, reciprocates while rotating, and protrudes to the outer periphery thereof. The hole to be machined is honed by the grindstone b.

  By the way, in the honing process, the honing grindstone G is structured to be exchangeably attached to the mandrel c of the honing tool as described above, but the shape of the grindstone b of the honing grindstone G is bad, Immediately after the honing tool mandrel c or the hoisting tool mandrel c or the extension wedge e has a dimensional variation in the tip wedge, the entire grindstone surface s of the grindstone b is drilled in the workpiece. Since it is not in uniform contact with the inner diameter surface, the machining accuracy (cylindricity, surface roughness) of the workpiece after honing is very poor.

  By continuing the honing process as it is, the entire grindstone surface s of the grindstone b finally comes into contact with the bore diameter surface of the workpiece to be machined, and the machining accuracy falls within the tolerance. There is little contact area of the abrasive grains with respect to the work hole inner diameter surface of the grindstone surface s of the grindstone b, and the abrasive grains fall off or wear, so that the entire grindstone surface s of the grindstone b contacts the work hole inner diameter face of the workpiece. It takes time to do. For this reason, it is necessary to repeat a number of honing operations until the cylindricity and surface roughness of the workpiece after the honing processing are stably within the tolerances, which increases the processing time loss and the number of defective products. There is a problem.

  For this reason, in the conventional honing process, a work called truing for adjusting the grindstone surface s of the grindstone b to a so-called R shape (cross-sectional arc shape) is generally performed immediately after replacement with a new honing grindstone G. (See (1) → (2) in FIG. 5 (a) and (1) → (2) in FIG. 5 (b)). In addition, after this truing, the abrasive grains on the grindstone surface s of the grindstone b usually do not protrude flush with the bond surface (see (2) in FIG. 5B). Very bad or not cut. For this reason, dressing work such as dressing after truing has been required (see (2) → (3) in FIG. 5B).

  As a truing method in the conventional honing process, there is a method shown in FIGS. 6A to 6C, and all of these truing operations are performed outside the honing machine.

  In the truing method of FIG. 6A, the honing grindstone G set on the mandrel c is inserted into the workpiece W to be machined, and the outer periphery of the honing grindstone G, the stone surface, and the inner diameter of the hole Wa to be machined are hit. While confirming the condition, it is a method of gradually removing from a place where the grindstone surface s of the grindstone b is high with a WA, GC grindstone or diamond file g. This method takes time and labor for the work, and the influence is great depending on the technical skill and skill level of the worker.

  In the truing method of FIG. 6B, the honing grindstone G set on the mandrel c is mounted on a cylindrical grinder using the special jig h, and the grindstone b is obtained by cylindrical grinding with a rotating grindstone i. This is a method in which the grinding wheel surface s is cut and trued. In this method, too much work is required. In this method, the grindstone surface of the grindstone b can be used only by a combination of the mandrel c set on the cylindrical grinder, the tip wedge of the expansion rod e, and the grindstone head a of the honing grindstone G. There was a problem that the shape accuracy of s could not be obtained (because there was a variation in the shape dimensional accuracy of individual component parts), and it could not be adopted for a mandrel with a single grindstone structure.

  In the truing method of FIG. 6C, the honing grindstone G set on the mandrel c is inserted into the cylindrical hole of the electrodeposited truing sleeve k formed by electrodeposition of the electrodeposited diamond j, and the electrodeposited diamond is inserted. This is a method of shaping while grinding the grindstone surface s of the grindstone b of the honing grindstone G. In this method, a dedicated electrodepositing truing sleeve k is required, the life of the electrodeposited diamond j is very short, the work cost is high, and the grindstone surface s of the grindstone b with the worn electrodeposited diamond j. However, there is a problem that dressing as post-processing must be sufficiently performed.

  Further, in these conventional truing methods, honing is possible because the shape accuracy can be obtained only when the tool (mandrel c, expansion rod e (tip wedge) thereof), grinding wheel base a, and grinding wheel b used at that time is set. There was also a problem that a honing tool such as a processing site was used as a set or a honing tool could not be borrowed as a set.

  Moreover, in the honing process, a superabrasive metal bond grindstone is generally used in which superabrasive grains such as diamond abrasive grains and CBN abrasive grains are bonded together by a metal binding material. This superabrasive metal bond grindstone is very hard and has a feature of low wear and long life, but because it is a material that is extremely hard to break due to the relationship between the front and back, it has been described above. Truing requires a great deal of time and effort, and also requires more technical skills and skill. Improvements have been demanded.

  As far as the present applicant knows, there is no patent document or the like that discloses these prior arts.

  The present invention has been made in view of such conventional problems. The object of the present invention is to provide a superabrasive metal bond grindstone and to perform truing and dressing operations at the beginning of mounting on a honing tool of a honing machine. An object of the present invention is to provide a honing grindstone having a structure that can obtain the desired machining accuracy of the workpiece by the initial honing process.

  In order to achieve the above object, the honing grindstone of the present invention is a rod-shaped one that is replaceably attached to the honing tool, and the square column grindstone is integrated with the grindstone base that is mounted and supported on the tool body of the honing tool. The above-mentioned grindstone is a superabrasive metal bond grindstone in which superabrasive grains such as fine diamond abrasive grains and CBN abrasive grains are bonded by a metal binding material, and this superabrasive metal bond grindstone The grindstone surface portion is formed from a brittle grindstone layer having a large number of irregular surfaces.

A preferred embodiment is configured as follows.
(1) The fragile grindstone layer is made of a material that is weaker and weaker than the constituent material of the workpiece to be processed.

(2) The brittle grindstone layer is composed of an electrolytic layer in which a large number of minute recesses are formed on the surface of the superabrasive metal bond grindstone by performing electrical processing on the grindstone surface portion.

(3) The thickness dimension of the fragile grindstone layer is set corresponding to the amount of dropout at the time of initial shaping after mounting on the honing tool.

(4) The electrical machining is electrical discharge machining.

(5) The electromachining is electrolytic machining.

  According to the honing grindstone of the present invention, there is provided a superabrasive metal bond grindstone in which superabrasive grains such as fine diamond abrasive grains and CBN abrasive grains are bonded by a metal binding material, and the grindstone of this superabrasive metal bond grindstone Since the surface portion is formed of a brittle grindstone layer made of a material that has a large number of uneven surfaces and is more fragile than the workpiece constituent material, various excellent effects listed below are exhibited, and the honing machine It is possible to provide a honing grindstone that does not require truing and dressing operations at the beginning of mounting on the honing tool, and can obtain the desired machining accuracy of the workpiece by the initial honing.

(1) The original truing and dressing is not required for the honing tool of the honing machine.

  That is, since the grinding wheel surface portion of the superabrasive metal bond grinding wheel is formed from a brittle grinding wheel layer having a large number of irregular surfaces, it is attached to the honing tool of the honing machine and honing the target workpiece In the first honing process, the brittle grinding wheel layer is worn and dropped, and the grinding wheel surface comes into contact with the work hole inner diameter surface of the workpiece. As a result, the grinding wheel surface has an R shape along the work hole inner diameter surface. To be shaped.

  As a result, the initial honing process absorbs the dimensional variation of the honing tool's grinding wheel base and the shape of the grinding wheel, as well as the dimensional variations of the hoddle tool's components, such as the mandrel and extension rod end wedge, and wear. Thus, a highly accurate truing effect can be obtained. Further, due to the presence of the fragile grindstone layer, a dressing effect can be easily obtained by the self-generated action of the grindstone surface during the honing process.

  Therefore, in the honing grindstone of the present invention, despite the fact that it is a super-hard abrasive metal bond grindstone, the truing and dressing work at the beginning of mounting on the honing tool, which has been required in the past, is no longer necessary. Simply by setting the honing tool on the honing machine, the desired machining accuracy can be obtained for the workpiece to be machined.

(2) In addition, the required accuracy can be satisfied even in roundness, and the surface roughness of the workpiece is measured from the beginning of honing (from the machining of the first workpiece) to the bore diameter of the workpiece. By hitting the surface more, it becomes closer to the surface roughness of the stable region.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The honing grindstone according to the present invention is shown in FIG. 1 and FIG. 2, and this honing grindstone 1 is specifically replaced with a mandrel 3 which is a tool body of the honing tool 2 as shown in FIG. 1 (b) and FIG. It is a rod-shaped grindstone that can be attached.

  The illustrated honing tool 2 includes a single honing grindstone 1, and is used by being exchangeably mounted on the front end or lower end of a rotating main shaft of a honing machine (not illustrated). The mandrel 3 is opened with a grindstone groove 3a for receiving and holding the honing grindstone 1, and the honing grindstone 1 is mounted in the grindstone groove 3a so as to protrude in the radial direction and to be removable and replaceable.

  Further, as shown in FIG. 2, an expansion rod 4 for expanding the honing grindstone 1 is provided in the mandrel 3 so as to be reciprocally movable in the axial direction, and the grindstone cutting device for the honing machine (not shown) ), The honing grindstone 1 is expanded (cut) radially outward by the tip wedge 4a of the expansion rod 4. Reference numeral 10 denotes a guide that guides the honing grindstone 1 concentrically within a hole to be machined. The guide 10 has a diameter equal to that of the honing grindstone 1 at the cylindrical outer periphery of the mandrel 3, as shown in FIG. It is embed | buried in the mandrel 3 so that it may oppose in the opposing position on a line.

  As shown in FIGS. 1 and 2, the honing grindstone 1 of this embodiment is a metal mold-integrated grindstone in which a grindstone 5 and a grindstone base 6 are integrally bonded and fixed.

 Specifically, the grindstone 5 is a superabrasive metal bond grindstone in which minute superabrasive grains are bonded by a conductive metal bonding material, and has a quadrangular prism shape. As the superabrasive grains, diamond abrasive grains, CBN (cubic boron nitride) abrasive grains or the like are used according to the purpose, and as the metal bonding material, copper, tin, cobalt, or an alloy containing them is used. A binding material made of at least one of these is used depending on the purpose. Further, the grindstone surface portion of the grindstone 5 is formed from a brittle grindstone layer 7 having a large number of uneven surfaces, as will be described later.

  The grinding wheel base 6 is a part that is mounted and supported on the mandrel 3, and a metal material such as copper or steel is suitably used as a constituent material thereof. The grindstone bed 6 of the illustrated embodiment uses a metal bond made of a copper alloy powder.

  As shown in FIG. 1B, the honing grindstone 1 in which the grindstone 5 and the grindstone base 6 are integrally joined in this way corresponds to the inner peripheral contour shape of the grindstone groove 3a of the mandrel 3 as shown in FIG. The bottom surface 1a of the expansion rod 4 provided in the mandrel 3 is an inclined surface corresponding to the inclined surface of the tip wedge 4a, and the expansion rod 4 moves forward in the axial direction. As a result of the cooperative action of the tip wedge 4 a of the rod 4 and the bottom surface 1 a of the honing grindstone 1, the honing grindstone 1 is expanded (cut) radially outward from the outer peripheral surface of the mandrel 3.

  The brittle grindstone layer 7 is formed in the final step in which the honing grindstone 1 is completed by joining the grindstone 5 and the grindstone base 6 in this manner.

  The formation of the brittle grinding wheel layer 7 is made by changing only the grinding wheel surface portion of the grinding wheel 5 while taking advantage of the fact that the grinding wheel 5 made of a superabrasive metal bond grinding wheel has a very high strength and a long life. The shape of the grindstone surface 5a can be reduced by making the portion of the grindstone surface 5a brittle and weaker than the constituent material of the workpiece to be machined by removing the grindstone in a normal honing process. This is because it is possible to finish a shape suitable for honing.

  For this purpose, the brittle grindstone layer 7 is made of a material that is brittle and weaker than the constituent material of the workpiece to be processed.

  Specifically, the fragile grindstone layer 7 is made of an electrolytic layer in which a large number of minute recesses are formed on the surface of the grindstone surface portion of the superabrasive metal bond grindstone 5 by electrical machining. Specifically, the electric machining includes electric discharge machining and electrolytic machining. In the present embodiment, the brittle grindstone layer 7 is formed by electric discharge machining as will be described later.

  Further, the thickness dimension of the fragile grindstone layer 7 is set corresponding to the amount of dropout at the time of initial honing processing (that is, at the time of initial shaping processing) after being mounted on the honing tool 2. This drop-off amount is the dimension due to the dimensional variation or wear of the tip wedge 4a of the mandrel 3 or the expansion rod 4 which is each component of the honing tool 1 as well as the dimensional variation of the grinding wheel base 6 of the honing grindstone 1 and the variation of the shape of the grindstone 5. It is an amount that can absorb changes and the like, and is set as appropriate in consideration of the machining accuracy required for machining the target workpiece.

  The formation process by electric processing of the fragile grindstone layer 7 and the initial honing processing in which the honing grindstone 1 as a finished product is mounted on the honing tool 2 will be specifically described with reference to FIG. Note that FIG. 3 is drawn schematically and greatly enlarged mainly for the purpose of facilitating understanding, but actually, the grindstone surface portion of the grindstone 5 is visually substantially flat, and The boundary between the fragile grindstone layer 7 and the main body portion of the grindstone 5 is not as clear as shown in the figure.

  The grindstone surface portion of the grindstone 5, that is, the surface layer portion including the grindstone surface 5 a, in an unprocessed state before being subjected to electrical machining, is shown in FIG. Are bonded by a conductive metal bonding material 16 to form a superabrasive metal bond grindstone.

  Next, electric processing is performed on the grindstone surface 5a portion of the unfinished grindstone 5, in order to reduce the amount of grindstone removal by electric machining and shorten the time, as shown in FIG. The surface shape of the grindstone surface portion is preliminarily adjusted by a conventionally known R polishing process (this pre-shaping step is selectively performed in consideration of the time required for electric processing, and may be omitted).

  The grinding wheel surface 5a portion of the grinding wheel 5 is subjected to electrical machining. In this embodiment, electric discharge machining is performed. Electrical discharge machining is not specifically shown, but as is conventionally known, the surface of the grindstone is generated by arc discharge repeated at short intervals between the electrode and the grindstone surface 5a of the grindstone 5 as the workpiece. Part of 5a is removed. In this case, the electrode is moved along the grindstone 5a in a non-contact proximity state to the grindstone surface 5a, so that the spark melts and evaporates a part of the grindstone 5a, so that the countless number on the grindstone surface 5a. A minute recess will be formed.

  As shown in FIG. 3C, the grindstone surface 5a after the electric discharge machining is very uneven, and the structure is very brittle and weak, and this is the brittle grindstone layer 7. The thickness dimension T of the fragile grindstone layer 7 having the uneven surface (= the grindstone surface 5a) can be set to a desired size by adjusting the strength of electric discharge in electric discharge machining.

  Thus, the honing grindstone 1 formed with the brittle grindstone layer 7 formed as described above is mounted in the grindstone groove 3a of the mandrel 3 of the honing tool 2 as shown in FIG. 1 (b) and FIG. Have been used. The honing tool 2 is attached to the tip of a rotating spindle of a honing machine (not shown), and the mandrel 3 is inserted into a work hole of a work (not shown) by driving the honing machine, and reciprocates while rotating. Then, honing of the hole to be machined is performed by the grindstone 1 protruding from the outer periphery.

  The first honing process also serves as a shaping process for the grindstone surface 5a of the grindstone 5, and the grindstone surface 5a of the grindstone 5 after the shaping process is in the state shown in FIG.

  That is, the brittle grindstone layer 7 of the grindstone 5 is composed of an electrolytic layer that is brittle and weaker than the constituent material of the workpiece to be machined. In other words, the workpiece that is to be machined more than the fragile grindstone layer 7. In the honing process, since the grinding wheel surface 5a, which is the surface portion of the fragile grinding stone layer 7, is higher in the uneven shape, the contact surface with the inner diameter surface of the hole to be machined is smaller. The grindstone 5 is gradually scraped from a high position on the grindstone surface 5a, and finally the entire grindstone surface 5a comes into contact with the bore diameter surface of the workpiece to be processed. That is, by increasing the strength of the falling layer of the grindstone surface 5a, that is, the weakened grindstone layer 7, the amount of whetstone falling off in each part in the vertical depth direction is adjusted according to changes in the processing load. The contact by the inclination of the grinding wheel surface 5a becomes uniform.

  Thus, in the case of the honing tool 2 having a single grindstone structure as in the present embodiment, the entire outer peripheral surfaces 5a and 10a of the grindstone 5 and the guide 10 are in contact with the inner diameter surface of the workpiece hole, The cross-sectional contour lines are parallel as shown in FIG. 2 (a), and the same circular cylindrical surface as shown by the phantom line circle in FIG. 2 (b) is formed.

  In addition, when the honing grindstone 1 of this embodiment is mounted on the honing tool 12 having a multiple grindstone structure (four in the illustrated case) as shown in FIG. 4, the grindstone surface 5a of each grindstone 5, 5,. Of the workpiece is evenly in contact with the inner diameter surface of the hole to be machined, and the cross-sectional outline is parallel as shown in FIG. 4 (a) and as indicated by the phantom line circle in FIG. 2 (b). The cylindrical surface of the same circle will be formed.

  As described above, in the honing grindstone 1 of the present embodiment, the grindstone 5 is made of a superabrasive metal bond grindstone, and the grindstone surface 5a portion of the superabrasive metal bond grindstone 5 has a number of uneven surfaces, and Because it is formed from the brittle grinding wheel layer 7 that is more fragile than the workpiece component material to be machined, truing and dressing work at the beginning is not necessary for the honing tool 2 of the honing machine. The machining accuracy of the workpiece can be obtained.

  That is, since the grindstone surface 5a portion of the superabrasive metal bond grindstone 5 is formed from the brittle grindstone layer 7 having a large number of irregular surfaces, it is attached to the honing tool 2 of the honing machine and the target workpiece is honed. By machining, the portion of the fragile grindstone layer 7 is worn and dropped by the first honing process, and the grindstone surface 5a hits the inner surface of the hole to be machined of the workpiece. As a result, as described above, the grindstone surface 5a Is shaped into an R shape along the inner surface of the hole to be processed.

  As a result, the dimensional variation of the grinding wheel base 6 of the honing grindstone 1 and the variation of the shape of the grindstone 5, as well as the dimensional variation of the mandrel 3 and the tip wedge 4a of the expansion rod 4 that are constituent elements of the honing tool 2, and the dimensional change due to wear. Is absorbed by the initial honing process (substantially the first honing process), and a highly accurate truing effect is obtained. Further, due to the presence of the fragile grindstone layer 7, a dressing effect can be easily obtained by the self-generated action of the grindstone surface 5a during the honing process.

  Therefore, in the honing grindstone 1 of this embodiment, even if the grindstone 5 is a high hardness superabrasive metal bond grind, it is processed only by setting it on the honing tool 2 of the user's honing machine. The desired machining accuracy can be obtained for the workpiece. As a test, it has already been found that even if there is some unevenness or inclination of the grindstone surface 5a of the grindstone 5, this can be absorbed and a cylindricity of 3 μm or less can be realized by the first honing.

  This means that the truing operation with the mandrel 3, the wedge 4a of the expansion rod 4 and the honing grind set in the state where the user who purchases this type of honing grind has been required is completely unnecessary. This means that the required machining accuracy can be achieved simply by setting the honing grindstone 1 surface-treated on the side to the mandrel 3 of the honing tool 1 on the machine of the honing machine owned by the user.

  Further, in the honing grindstone 1 of the present embodiment, the required accuracy can be satisfied even in the roundness of the work, and the grindstone surface 5a of the honing grindstone 1 from the beginning of the honing is also achieved with respect to the surface roughness of the work. The surface roughness of the stable region is closer due to the large contact with the inner diameter surface of the workpiece hole.

  The above-described embodiment is merely a preferred embodiment of the present invention, and the present invention is not limited thereto, and various design changes can be made within the scope.

  For example, the honing grindstone 1 of the illustrated embodiment is for a honing tool 2 having a single honing grindstone applied thereto, but as is apparent from the above description with reference to FIG. Of course, it is applicable to honing tools having a plurality of honing grindstones such as three or four.

  In the illustrated embodiment, the brittle grindstone layer 7 is formed by electric discharge machining, but can also be formed by wire electric discharge machining which is a kind of electric discharge machining.

  That is, when the brittle grindstone layer 7 is formed by this wire electric discharge machining, although not specifically shown, a thin metal wire is sent close to the grindstone surface 5a. The advantages of this wire electric discharge machining are that it is possible to cut out a very complicated and fine shape, and the difference in shape such as the height, width, and R size of the grindstone 5 can be freely set, and the workability is good. For example, the size of the unevenness of the grindstone surface 5a can be freely set by the metal wire moving zigzag in the vertical direction along the grindstone surface 5a.

  Further, the brittle grindstone layer 7 can be formed by electrolytic machining belonging to the same electric machining instead of the electric discharge machining. Electrochemical machining is similar to electrical discharge machining in that a large current is passed between the electrode and the grindstone 5 that is the workpiece, and the electrode for electrolytic machining does not contact the grindstone surface 5 a of the grindstone 5. Thus, the proximity position of the grindstone surface 5a is moved.

  Furthermore, the present invention is not limited to the metal mold-integrated grindstone as in the illustrated embodiment, and can be applied to other similar honing grindstones.

FIG. 1A is a perspective view, and FIG. 1B is an exploded perspective view seen from the front of a mandrel of a honing tool having a single grindstone structure to which the honing grindstone is mounted. The mandrel of the honing tool with which the honing grindstone was similarly mounted | worn is shown, Fig.2 (a) is front sectional drawing, FIG.2 (b) is sectional drawing along the BB line of Fig.2 (a). FIG. 3A is an enlarged schematic diagram showing a grindstone surface portion of a superabrasive metal bond grindstone in the honing grindstone, FIG. 3A is an unprocessed state, FIG. 3B is a state after R polishing, FIG. c) shows a state after electric discharge machining, and FIG. 3 (d) shows a state after the first honing. FIG. 4A is a front sectional view of a honing tool having a four-grinding wheel structure on which the honing stone is mounted, FIG. 4B is a sectional view taken along line BB in FIG. It is. FIG. 5 (a) shows a mandrel of a honing tool having a single grindstone structure to which a conventional honing grindstone is mounted. (1) is a state before truing processing of the honing grindstone, and (2) is after truing processing of the honing grindstone. FIG. 5 (b) is a schematic cross-sectional view showing an enlarged surface portion of the honing grindstone, (1) before truing processing, (2) after truing processing, and (3) after dressing. Each is shown. FIGS. 6A to 6C each show a conventional honing method for a honing grindstone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Honing wheel 2 Honing tool 3 Mandrel 3a Mandrel grindstone groove 4 Expansion rod 4a Extension rod tip wedge 5 Grinding wheel 5a Grinding wheel surface 6 Grinding wheel base 7 Fragile wheel layer 10 Guide 15 Super abrasive 16 Metal bonding material T Thickness dimension

Claims (6)

It is a rod that can be attached to the honing tool in an exchangeable manner,
A grindstone in the shape of a square pillar is integrally joined to a grindstone table that is mounted and supported on the tool body of the honing tool,
The grindstone is a superabrasive metal bond grindstone in which superabrasive grains such as fine diamond abrasive grains and CBN abrasive grains are bonded by a metal binding material,
A honing grindstone characterized in that a grindstone surface portion of the superabrasive metal bond grindstone is formed of a brittle grindstone layer having a number of irregular surfaces. The honing grindstone according to claim 1, wherein the brittle grindstone layer is made of a material that is brittle and weaker than a constituent material of a workpiece to be processed. The fragile grindstone layer is composed of an electrolytic layer in which a large number of minute recesses are formed on the surface of the superabrasive metal bond grindstone by applying electrical processing to a grindstone surface portion. Or the honing grindstone of 2. The honing grindstone according to any one of claims 1 to 3, wherein the thickness dimension of the brittle grindstone layer is set in accordance with a dropout amount at the time of initial shaping after mounting on the honing tool. .  The honing grindstone according to claim 3, wherein the electric machining is electric discharge machining. The honing grindstone according to claim 3, wherein the electric machining is electrolytic machining.

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