JP5946728B2 - Centerless grinding method for shaft member and method for manufacturing circular shaft member - Google Patents

Description

  The present invention relates to a shaft member centerless grinding method for grinding a shaft member which is a workpiece (workpiece) without being supported at the centers of both ends thereof, and a circular shaft member manufacturing method using the method.

  In centerless grinding (centerless grinding) when the shaft member is a difficult-to-cut material, the grinding part, etc. is cooled, heat generation is prevented, cleaning, the accuracy of the ground surface is maintained, and grinding. It is extremely important to supply a grinding fluid (cooling fluid) for smoothing the surface and extending the life of a grinding wheel or the like. Therefore, in this type of grinding (or polishing), it is common to continue supplying the grinding liquid to the surface of the grinding wheel layer of the grinding wheel or the grinding part via a supply pipe or the like (for example, Patent Document 1). ). In particular, when centerless grinding of a shaft member (also called a workpiece) of a difficult-to-cut material such as ceramic, an expensive diamond grindstone is used, so that the grinding liquid is applied to the entire surface (outer peripheral surface) of the grindstone layer. In addition, it is important to supply the grinding part so as to spread efficiently.

  However, in such centerless grinding, of the surface of the grindstone layer responsible for grinding (the outer peripheral surface of the cylinder), the portion parallel to the rotation axis is a straight line, and the surface of the shaft member that is pressed and cylindrically ground here The same applies to (the outer peripheral surface of the cylinder). For this reason, even if the grinding fluid can be supplied to the outer peripheral surface of the grinding wheel, that is, the entire surface of the grinding wheel layer, the grinding liquid is ground to the outer peripheral surface and the actual grinding portion of the outer peripheral surface of the workpiece pressed against the grinding wheel. It is not easy for the liquid to sufficiently wrap around. That is, in normal centerless grinding, the actual situation is that the grinding fluid cannot be smoothly supplied to such a grinding portion.

JP 2001-138187 A

  For this reason, in conventional centerless grinding, the cooling performance of the grinding part is insufficient, and the grinding wheel (hereinafter, also simply referred to as a grinding wheel) tends to become high temperature. Problems such as (bond) burn occurred, resulting in a decrease in the sharpness of the grindstone and a shortening of its life due to falling off of the abrasive grains. In addition, as described above, when the workpiece is a difficult-to-cut material such as ceramic, the burden on the grindstone is large, and thus such a problem tends to occur. Specifically, it is as follows. That is, when looking at such problems with a grindstone, for example, when grinding with a normal through-field method that feeds a workpiece in the direction of the rotation axis, grinding on the workpiece input side (inlet side) of the grindstone The resistance or grinding load is definitely greater than the discharge side (exit side). For this reason, uneven wear or local wear in which the input side wears quickly on the surface of the grindstone tends to occur, and the sharpness tends to be lowered quickly. As a result, it is necessary to change (change) the end face (input side) of the grindstone in order to maintain balance at an early stage, and to make correction (truing) to maintain its surface accuracy (sharpening) at an early stage. Therefore, the grinding wheel layer (diamond) tends to wear quickly, resulting in a reduction in the life of the grinding wheel. Moreover, there is a problem due to seizure of the support blade (blade).

  Also, if the workpiece is ceramic and has a burned surface immediately after firing, and the cross-sectional shape is an irregular circle or a polygon (not an iso-diameter round), the grinding resistance is It is large and problems such as uneven wear tend to be obvious. For example, multiple workpieces are manufactured by cutting and individualizing workpieces by hot pressing with the outer peripheral surfaces of adjacent workpieces in contact with each other and firing after firing. This work has a fracture surface at the time of cutting on both sides of the outer peripheral surface. A workpiece having such a poor cross-sectional state inevitably has a large grinding resistance, and problems such as uneven wear on the grindstone are easily manifested. Moreover, since the grinding resistance is large, defects such as bending and cracking are likely to occur in the workpiece itself during the grinding process, which has been a factor in yield reduction. In addition, the grinding of such workpieces has a problem of increased noise because of the cross-sectional shape of the workpiece, resulting in unsmooth grinding.

  The present invention has been made in view of the above-described problems. In centerless grinding of a workpiece (shaft member) made of a difficult-to-cut material such as ceramic with a diamond grindstone, the grinding liquid (cooling liquid) is the outer periphery of the grindstone. It is an object of the present invention to provide a technique capable of effectively and sufficiently spreading to a grinding part (a part actually entrusted to grinding) of a surface where a workpiece is actually ground.

The present invention according to claim 1 is a centerless grinding method of a shaft member using a grinding wheel whose grinding wheel layer is made of a diamond grinding wheel,
On the outer peripheral surface of the grinding wheel layer of the grinding wheel, so that the grooves extending in the circumferential direction, a plurality at intervals in the rotation axis direction of the own kicked set,
The grinding wheel is composed of a splittable assembly in which a plurality of divided grinding wheels are stacked and fixed by bolting in the direction of the rotation axis. The divided grinding wheel includes a divided grinding wheel having a metal divided wheel main body and the grinding wheel layer formed narrower than the width of the divided grinding wheel so that the groove is formed therebetween. characterized in that it was.
The present invention according to claim 2 is a centerless grinding method of a shaft member using a grinding wheel whose grinding wheel layer is made of a diamond grinding wheel,
A groove extending spirally around its rotation axis is provided on the outer peripheral surface of the grinding wheel layer of the grinding wheel.

3. The shaft member centerless grinding method according to claim 1, wherein the groove has a groove width smaller than an outer diameter of the shaft member after grinding. It is.
According to a fourth aspect of the present invention, the grinding wheel is composed of a splittable assembly formed by stacking and fixing a plurality of divided grinding wheels in the rotational axis direction, and is overlapped in the rotational axis direction. The divided grindstone having the metal divided wheel main body and the grindstone layer formed narrower than the width on the outer peripheral surface of the divided grindstone so that the groove is formed between the adjacent divided grindstones. The centerless grinding method for a shaft member according to claim 2, comprising a vehicle.

A fifth aspect of the present invention is a method for manufacturing a circular shaft member, including a grinding step using the centerless grinding method for a shaft member according to any one of the first to fourth aspects.
The present invention according to claim 6 is the method of manufacturing a circular shaft member according to claim 5, wherein the shape of the cross section of the shaft member before grinding is a polygon or a non-circular shape.
The present invention according to claim 7 is the method of manufacturing a circular shaft member according to claim 5 or 6, characterized in that the shaft member has ceramic as a main component.

  According to the centerless grinding method of the present invention and the method of manufacturing a circular shaft member including a grinding step using the method, the groove is provided on the outer peripheral surface of the grinding wheel layer of the grinding wheel used in the method. Therefore, as compared with the case of the centerless grinding method using a grinding wheel without the grinding wheel, the grinding liquid supplied in the grinding process is more likely to go around the grinding portion of the outer peripheral surface of the grinding stone as much as it is provided. For this reason, excellent smooth grinding such as cooling effect or heat dissipation effect is performed. Thereby, for example, even when the shaft member is supplied and ground one after another in the axial direction from one end side (workpiece supply side) to the other end side (workpiece discharge side) of the grinding wheel in the through field method. Further, uneven wear (local wear) on the supply side of the grinding wheel having a large grinding load can be reduced. Thereby, the frequency | count of the change (change) of the edge side of a grindstone, and its operation | work time can be reduced. Moreover, the sharpness fall of a grindstone can be delayed. As a result, the number of times of truing of the grindstone can be reduced, and effects such as extending the life of the grindstone can be obtained. When a plurality of grooves extending in the circumferential direction are provided at intervals in the direction of their own rotation axis, the grooves are equally spaced in the width direction so that the grinding liquid spreads over the entire surface in the width direction of the grindstone. Therefore, it is preferable to provide as many as possible.

  In addition, when looking at the shaft member that is the workpiece to be ground, smooth grinding with high cooling effect or heat dissipation effect is performed by the amount of the groove, so that it is made of brittle ceramic and has a non-circular cross-sectional shape ( Even a non-equal-diameter round product) is less prone to grinding failure such as bending, and is effective in preventing a decrease in yield. Moreover, even if the shaft member has such a poor cross-sectional shape and becomes a severe grinding condition for the grinding wheel, resulting in a decrease in the service life and an increase in grinding noise, according to the present invention, the groove is provided. Since the grinding fluid is excellent in wrapping around the outer peripheral surface of the grindstone, it is also effective in preventing such problems.

  In this invention, the cross-sectional shape of the groove | channel of the outer peripheral surface of the said grindstone layer can be made into appropriate cross-sectional shapes, such as a rectangle, V shape, and U shape. In addition, the number or pitch of the grooves (or leads in the case of spiral grooves), the width and depth of the groove, the material and dimensions of the workpiece to be ground, and the workpiece feed rate Alternatively, the surface condition of the workpiece, the grain size of the abrasive grains of the grindstone, and the grinding fluid supply flow rate may be set as appropriate. That is, the grinding liquid may be set on the basis of the grinding conditions so that the grinding liquid is wide on the outer peripheral surface of the grinding wheel (the entire width direction on the surface of the grinding wheel) and can efficiently wrap around the actual grinding site. In the present invention, the centerless grinding is normally performed by the through field method in which the adjustment wheel is given an up and down inclination so that the workpiece is fed in the rotation axis direction. Applicable.

  In addition, when it is set as a spiral groove | channel, since the wraparound property of a grinding fluid can be improved, a grinding fluid can be spread widely widely in the width direction of a grinding wheel. When it is set as such a helical groove | channel, it is good also as one spiral, but it is good also as two or more spirals. Further, as described above, the groove width may be set appropriately according to the grinding conditions. However, since the ceramic elongated shaft member is easily broken, the broken piece fits into the groove depending on the groove width dimension. There is a possibility that. In order to prevent the fitting, the width of the groove is preferably smaller than the outer diameter of the shaft member after grinding as described in claim 3. The depth of the groove should be deep in view of the ability of the grinding fluid to enter and flow. On the other hand, if the groove is deep, the possibility that the broken piece is fitted increases. For this reason, although it depends on the depth, the width of the groove is as small as possible from the outer diameter of the shaft member to be ground, preferably 80% or less, particularly preferably 60% or less. However, it is preferable that the width of the groove is 1.0 mm or more at a minimum from the viewpoint of penetration of the grinding fluid and prevention of clogging. It is efficient in manufacturing the grinding wheel that the depth of the groove is the same as the thickness of the diamond grinding wheel layer. In this case, since there is a groove where there is no diamond grindstone layer, it is only necessary to form the grindstone layer only in a portion where the groove is not formed.

According to the grinding wheel having the assembly structure according to claim 1 or 4, since the groove is formed in the assembling process, the grinding wheel can be easily manufactured. Moreover, the width of the grinding wheel itself can be easily changed or selected depending on the number of divided grinding wheels, and the grinding wheel can be partially replaced. In addition, in this specification, each of the grinding wheels that can be divided into a plurality of parts that constitutes a grinding wheel composed of an assembly that is overlapped and fixed in the rotation axis direction is referred to as a divided grinding wheel, and one of these divided grinding wheels. The grinding wheel main body excluding the grinding wheel layer constituting the car is referred to as a divided vehicle main body.

  In centerless grinding, for example, in order to finish a shaft member made of ceramic by a through-field method from a burned skin state immediately after firing to a high-quality surface roughness and high-precision round bar, the grinding process includes a plurality of grinding processes. A grinding process (for example, 2-5 processes) is required. In particular, the shaft member forming the workpiece is immediately after firing as described above, and the outer peripheral surface has a fractured surface generated when it is individually folded (cut). When it is a square or non-circular object and is finished into a circular shaft member, the burden on the grindstone used for the first grinding is particularly large. Therefore, even if it is a case where the life of the grindstone is shortened, according to the present invention, since the groove is present, the wraparound property of the grinding fluid to the grinding portion is improved as compared with the case where there is no groove. In addition, the service life of the grindstone can be extended and the reduction of noise can be effectively prevented. For this reason, according to the manufacturing method of the circular shaft member of this invention, a big effect is acquired especially when a shaft member is a thing which contains a ceramic as a main component and a cross-sectional state is bad.

A grinding wheel and an adjustment wheel, which are the main parts of a centerless grinding machine, for explaining a manufacturing method ( reference embodiment ) of a circular shaft member using a centerless grinding method that embodies a reference invention different from the present invention. FIG. 2 is a schematic configuration diagram showing an arrangement of support blades and the like, in which A is an elevation view and B is a plan view thereof. FIG. 2A is a perspective view of the grinding fluid supply pipe as viewed from obliquely above in FIG. The figure explaining the cross-sectional shape of a shaft member. In FIG. 2, the perspective view of another example which made the groove | channel provided in the grinding wheel spiral. It is explanatory drawing which assumed that the grinding wheel of FIG. 1 consists of a some division | segmentation grinding wheel, Comprising: The upper figure (A) is a figure explaining a division | segmentation state, and the lower figure (B) is explanatory drawing of the grinding wheel after an assembly. . It is a figure explaining the other example of the grinding wheel which consists of an assembly, Comprising: A is the half sectional view and the elements on larger scale, B is a right view of A. It is a figure explaining the further another example of the grinding wheel which consists of an assembly, Comprising: The half sectional view and the partial enlarged view.

Before explaining an embodiment of the present invention, as a reference embodiment of a reference invention different from the present invention , a centerless grinding method and a method of manufacturing a circular shaft member including a grinding step using the centerless grinding method ( Reference Example) will be described in detail with reference to FIGS. 1 and 2 show a grinding wheel 10 and an adjustment wheel 20, which are main parts of a centerless grinding machine, and a support blade (blade) 30 and the like arranged so as to be sandwiched between the grinding wheel 10 and the two in plan view. Is. That is, the grinding wheel 10 and the adjustment wheel 20 are arranged in parallel in plan view so that the center distance between the rotating shafts 11 and 21 can be adjusted, and the support blade (blade) arranged so that the position can be adjusted between them. 30 is provided. Further, as shown in FIG. 1-A, above the grinding wheel 10, the tip (discharge port) 41 of the supply pipe 40 for supplying the grinding fluid is used to feed the grinding fluid to the outer peripheral surface of the grinding wheel 10, that is, the grinding wheel 10. The outer circumferential surface 16 of the grindstone layer 15 is opened downward so as to be exposed to a portion near the shaft member 101 that is a workpiece. Thereby, it sets so that a grinding fluid can be supplied between the grinding wheel 10 and the shaft member 101 (grinding site | part). However, the tip 41 of the pipe 40 is provided so as to be opened at a plurality (two in this reference example (hereinafter also referred to as this example )) at intervals along the rotating shaft 11 of the grinding wheel 10. The grinding fluid is set to be supplied to the entire width direction of the grinding wheel 10. In addition, in order to send the shaft member 101 being ground in the axial direction (applying a propulsive force), the rotary shaft 21 of the adjusting wheel 20 (for example, the outer peripheral surface is made of rubber) pressed against the shaft member 101 as a workpiece is a grinding wheel. Although not shown in the figure when viewed from the side with respect to the ten rotation shafts 11, they are tilted by a small angle. As described above, the arrangement of the grinding wheel 10 and the like is the same as that of a conventionally known centerless grinding machine, and only the configuration of the grinding wheel 10 is different. For this reason, the grinding method and the like will be described below centering on this difference.

  However, the shaft member 101 which is a workpiece to be ground in this example is a rod made of ceramic (made of silicon nitride). Specifically, it is a ceramic heater member for glow plugs used for promoting ignition of diesel engines. In FIG. 1 and FIG. 2, this is simply shown as a short cylindrical shape for ease of explanation, but in reality, a resistance heating element (not shown) is provided in an embedded state. Is a long and thin round bar having an outer diameter of φ3.5 mm after final finishing. In addition, as shown in FIG. 3, the shaft member 101 is an aggregate 100 in which a large number are connected to each other on both sides forming the outer peripheral surface when viewed from one end side, as shown in FIG. Thereafter, the cross-sectional shape after being divided individually by breaking (breaking) the side surface of each part is as shown in an enlarged manner in FIG. That is, the shaft member 101, which is a starting material before grinding, is a bar that has an irregular shape that should be called a polygon or a non-circular shape, and extends straight and long.

  On the other hand, the grinding wheel 10 used in this example has a grinding wheel layer 15 formed in a layered shape including a binder and the like using diamond as abrasive grains on the outer peripheral surface of a metallic grinding wheel main body 13. The outer diameter of the grinding wheel 10 on the outer peripheral surface 16 formed by the grinding wheel layer 15 is 200 mm, and the width is 100 mm. In this example, the abrasive grains have a particle size of No. 120. Moreover, the thickness of the grindstone layer 15 is set within a range of 1 to 10 mm. In such a grinding wheel 10, as shown in FIGS. 1B and 2, the outer circumferential surface 16 of the grinding wheel layer 15 has a groove 18 extending continuously in a circumferential manner in the circumferential direction. A plurality of cuts are formed at regular intervals. However, the groove 18 has, for example, a rectangular groove whose cross-sectional shape is narrow, the width W is 1 mm (or 2 mm), and the depth D is 5 mm. However, the pitch between the grooves 18 is 10 mm. In this example, the shaft member 101 is continuously supplied to such a grinding wheel 10 by the through field method, and the outer peripheral surface 16 is cylindrically ground. Therefore, the adjustment wheel 20 and the support blade 30 described above are used. The position is adjusted and held.

  Thus, the outer periphery of the grinding wheel 10 that rotates at a relatively high speed while giving rotations at different rotational speeds in the same direction to the grinding wheel 10 and the adjustment wheel 20 as indicated by arrows in the figure. Grinding liquid is discharged from the front end of the supply pipe 40 onto the surface 16 (grindstone layer 15). Under this state, the shaft member 101 is supplied one after another from the one end face (lower side of FIG. 1-B, left side of FIG. 2) of the grinding wheel 10 and is elastically pressed from above by the pressing member 35. . By doing so, each shaft member 101 is rotated, and grinding is performed by the grinding wheel 10. Since each shaft member 101 is fed in the axial direction (propulsive force) by the adjusting wheel 20, one side of the grinding wheel 10 (below FIG. 1-B, left in FIG. 2) while being cylindrically ground. Is sent to the other side and discharged. In this way, the shaft member 101 which is a workpiece is ground one after another by the through field method. The second and subsequent rounds of grinding are repeated for a desired number of times, so that a circular member having a circular cross-sectional shape and an outer diameter that are finally desired, that is, a ceramic heater member (cylindrical grinding finished product) ) Is obtained.

  In the grinding step, the grinding liquid discharged from the tip 41 of the supply pipe 40 is supplied to the grinding surface of the outer circumferential surface 16 and the shaft member 101 together with the outer circumferential surface 16 of the grinding wheel 10, and grinding is performed therein. Is called. In this grinding process, in this example, a plurality of grooves 18 are provided on the outer peripheral surface 16 of the grinding wheel layer 15 (diamond grinding wheel layer 15) of the grinding wheel 10 as described above. For this reason, the grinding liquid is supplied to the outer peripheral surface 16 of the grindstone layer 15, enters the groove 18, and goes around in the circumferential direction. Thereby, according to the centerless grinding method of this example using such a grinding wheel 10, compared with the case of grinding using a conventional grinding wheel in which the grinding wheel 10 does not have the groove 18 as described above, the groove As much as 18, the grinding fluid is surely and well distributed to the outer peripheral surface 16 of the grinding wheel 10 (grinding wheel layer 15) and the grinding site between the grinding wheel 10 and the workpiece. For this reason, as compared with the case of the conventional grinding method, the grinding is performed in a state where the grinding liquid is sufficiently washed while the grinding liquid is sufficiently washed. Thus, the following specific effects can be obtained.

  That is, in the manufacturing method of the circular shaft member including the grinding process using the centerless grinding method according to the present example, the groove 18 is provided on the outer peripheral surface 16 of the grinding wheel layer 15 forming the cylinder of the grinding wheel 10, so Compared with the case of the conventional grinding method using a grinding wheel having no groove on the surface, the grinding liquid is efficiently supplied to the grinding portion by the amount of the groove 18. For this reason, smooth grinding with a high heat dissipation effect is performed accordingly. Thus, even if the shaft member 101 is ground by the through-field method, the end surface side (the lower side of FIG. 1-B, the left side of FIG. 2) of the outer peripheral surface 16 of the grinding wheel 10 (the lower side of FIG. 1-B) It is also possible to reduce uneven wear (local wear) that tends to occur in the shift part). As a result, the number of changes on the input side of the grinding wheel 10 (replacement of the end face in the grinding wheel 10) can be reduced, and the number of sharpening can also be reduced. Thus, according to the grinding method of this example and the manufacturing method of the circular shaft member using the same, the grinding efficiency can be increased and the life of the grinding wheel 10 can be extended. Incidentally, from the actual measurement results by the inventors of the present application, the number of shaft members 101 that can be ground with one grinding wheel 10 is twice or more on average as compared with the case where a conventional grinding wheel without grooves 18 is used, that is, The service life of the grinding wheel 10 has more than doubled.

  Moreover, even if the workpiece to be ground as in this example is the shaft member 101 made of a long and brittle ceramic, the grinding fluid can be well distributed to the grinding site and wrap around by using the grinding wheel 10. Since the heat dissipation effect is enhanced and smooth grinding is performed, the shaft member 101 is unlikely to be broken or broken. As a result, it is possible to prevent the occurrence of grinding failure and to prevent the yield from decreasing. Moreover, as in this example, when the shaft member is broken as described above after firing and the cross-sectional shape thereof is irregular, the load applied to the grinding wheel 10 is extremely severe, When grinding is performed under the conditions, the burden of the grinding liquid can be reduced by the smooth distribution of the grinding liquid in the groove 18 to the surface of the grindstone layer 15. Therefore, in the conventional grinding, the generated noise has been very large, but the noise can be reduced.

Further, in the centerless grinding of a shaft member made of a brittle ceramic material as in this example, bending, cracking, etc. are inevitably generated in the grinding process, and the cut piece is fitted into the groove 18. In this reference example , the width W of the groove 18 is sufficiently smaller than the outer diameter (φ3.5 mm) of the shaft member 101 and 1 mm (or 2 mm). It is said. For this reason, the occurrence of such a problem can be prevented almost certainly. As a result, it is possible to avoid grinding problems caused by the inserted cut pieces and interruption of the grinding work for removing them. The depth D of the groove 18 is preferably deeper in order to ensure the flowability of the grinding fluid. On the other hand, it is preferable to make the width W of the groove 18 as small as possible as compared with the outer diameter of the shaft member 101 which is a workpiece in order to prevent the broken pieces from being inserted.

In the above reference example , the groove 18 provided on the outer peripheral surface 16 of the grinding wheel 10 is embodied as a plurality of independent grooves 18 having a circumference, but is used in the embodiment of the present invention. In the grinding wheel 10, as a spiral groove, as in another example shown in FIG. 4, the groove 18 </ b> S is continuously extended spirally in the rotation axis direction on the outer peripheral surface 16 of the grinding wheel layer 15. It may be formed. When such a spiral groove 18S is used, the groove 18S can be continuously present in the width direction of the outer peripheral surface 16 of the grinding wheel 10. For this reason, a grinding liquid can be made to wrap around more widely in the width direction in a grinding part. Thereby, according to such a helical groove | channel 18S, the cooling property of the grinding | polishing site | part by a grinding fluid and the smoothness of grinding are improved further. In the example of the grinding wheel 10 used in the embodiment of the present invention shown in FIG. 4, only the point that the groove 18S is spiral is different from the above example. Stop it. When the groove is an independent groove 18 having a circumference as in the above reference example , the groove 18 is basically provided so as to pass through one virtual plane perpendicular to the rotation axis. It can also be provided without passing through a virtual plane.

By the way, the grinding wheel 10 used in the above reference example and FIG. 4 is a groove 18 (circumferential) extending along the circumferential direction at an interval in the width direction on the outer peripheral surface of one metallic grinding wheel main body 13. It is assumed that the grindstone layer 15 made of diamond is formed so that there are a plurality of grooves 18) or a spiral groove 18s. However, in the present invention, such a grinding wheel 10 is divided into a plurality of narrow (thin) grinding wheels (divided grinding wheels) 50b as shown in FIG. As shown in FIG. 5B, it may be embodied as a grinding wheel 10 made of a combination formed by overlapping and fixing in the direction of the rotation axis 11. In addition, although a fixing means is not shown in figure, what is necessary is just to perform by bolting etc. so that it may mention later. In this, a plurality of divided grinding wheels having a divided wheel main body 53 made of metal and a grinding wheel layer 15 formed narrower than the width (thickness of the divided wheel main body 53) on the outer peripheral surface thereof are used for the divided grinding wheel 50b. ing. Thus, as shown in the figure, by assembling such a divided grinding wheel 50b so as to overlap in a fixed direction, a groove 18 is formed between the grinding wheel layers 15 of the adjacent divided grinding wheels 50b. It is formed. This is convenient because the width of the grinding wheel 10 itself can be easily changed or selected depending on the number of divided grinding wheels, and can be partially replaced. In FIG. 5, the grindstone layer 15 is formed over the entire width of the leftmost divided grinding wheel. In addition, what was shown in FIG. 6 is illustrated as an example of improvement of the assembly type grinding wheel which consists of this division grinding wheel.

  The grinding wheel 50 shown in FIG. 6 is composed of an assembly of the same plurality of divided grinding wheels 50b. Each of the divided grinding wheels 50b includes a divided wheel main body 53 and a grinding wheel layer 15 formed on the outer peripheral surface 54a. Formed from. Among these, the split vehicle main body 53 is smaller than the outer diameter of the disk main body 53a so that the split disk main body 53 has a concentric and different diameter in the metal disk main body 53a having a constant thickness. A convex circular portion 53b having an outer diameter and protruding at a certain height is provided. Thus, the divided vehicle main body 53 has outer peripheral surfaces 54a and 54b that form two cylinders having different diameters. The grindstone layer 15 has a predetermined thickness over the entire width of the outer peripheral surface 54a of the disc body 53a having a larger diameter than the convex circle portion 53b of the divided wheel main body 53, and the grindstone layer 15 made of diamond (abrasive grains). Is formed. On the other hand, on the other end face side of the disc main body 53a, the convex circular portion 53b can be fitted, and has a constant inner diameter dimension, and is shallower (smaller) than the protruding height (projection amount) of the convex circular portion 53b. Concentric concave portions 53c that are depressed at a certain depth are provided.

  In the center of the divided wheel main body 53, a shaft hole 51 is provided for mounting a rotating shaft of a grinding wheel 50 constituted by assembling them. Also, the divided wheel main body 53 is provided with, for example, eight bolt holes 52 for fixing a plurality of divided grinding wheels 50b in the axial direction at equal angular intervals on the concentric circle with the shaft hole 51. ing.

  Thus, the grinding wheel 50 of this example prepares a plurality of the above-described divided grinding wheels 50b, and fits the other convex circle portion 53b to one concave circle portion 53c of the adjacent divided grinding wheel 50b. And the bolt holes 52 are matched. The bolt hole 52 is assembled by passing the bolt 60 and tightening and fixing the nut 62. In the grinding wheel 50 assembled in this way, the depth of the concave circle portion 53c is shallower than the raised height of the convex circle portion 53b, so that the difference is the groove 18 (width of the groove 18) in the grinding wheel layer 15. Become. Since this structure has the above-mentioned fitting structure when the divided wheel main body 53 is stacked, the stability of the fixing is high, and the groove 18 is made larger than the thickness of the grindstone layer 15, so that the flow of the grinding fluid is increased. A large road cross section is secured. And also in this thing, the width | variety of the whole grinding wheel 50, ie, the grinding wheel layer 15, can be adjusted by adjusting the number of the division grinding wheels 50b to pile up according to the length of a workpiece | work.

  FIG. 7 shows another example in which the grinding wheel 50 of FIG. 6 is further improved. In this example, in the previous example, one separate grinding wheel 50b that does not have the concave circle portion 53c in the divided grinding wheel 50b and one divided grinding wheel 50b that does not have the convex circle portion 53b in the divided grinding wheel 50b. In the grinding wheel 50 having the above-described assembly structure, these are assembled by being fitted to each end. In other words, as shown in FIG. 7, the former divided grinding wheel 50b prepared separately at the right end of the grinding wheel 50 and the latter divided grinding wheel 50b at the left end are overlapped in the direction of the rotation axis, as shown in FIG. As in the previous example, the convex circle portion 53b and the concave circle portion 53c are fitted and fixed. In the grinding wheel 50 shown in FIG. 7, for example, a counterbore is provided in the bolt hole 52 of one outermost divided grinding wheel 50b (the right end in the drawing), and the other outermost grinding wheel 50b (shown in the drawing). If a screw hole 52b is provided in place of the bolt hole at the left end and is directly screwed in and fixed through a hexagon socket bolt 70 as shown in the figure, there are no protrusions (protrusions) or recesses on both end faces, and the grinding wheel 50 The overall shape can be simplified.

  The present invention is not limited to the examples described above, and can be embodied with appropriate modifications without departing from the scope of the invention. In the above example of the grinding wheel, the groove provided in the grinding wheel layer is exemplified by a case where the cross section is rectangular (square or rectangular). However, as described above, the shape of the groove is the flowability of the grinding fluid ( As long as there is no hindrance to the wraparound property, an appropriate cross-sectional shape such as a V shape or a U shape can be used. Further, the width and depth of the grooves, the pitch between the grooves, and the like may be set according to the difficult-to-cut property of the workpiece, the outer diameter, and the like. It is obvious that the shaft member (or the circular shaft member) in the grinding method and the manufacturing method of the present invention may be not only a solid shaft member but also a hollow shaft member (cylinder). Further, the cross-section of the shaft member to be ground or the shaft member before being ground of the manufactured circular shaft member may be a round bar (equal diameter round object). Furthermore, these workpieces may be ceramics other than silicon nitride, or other difficult-to-cut materials (cemented carbide).

10, 50 Grinding wheel 11 Rotating shaft 15 Grinding wheel layer 18, 18s Groove 16 Grinding wheel outer peripheral surface 50b Divided grinding wheel 53 Divided vehicle main body 54a, 54b Divided vehicle main body outer peripheral surface 101 Shaft member

Claims (7)

A centerless grinding method for a shaft member using a grinding wheel whose grinding wheel layer is composed of a diamond grinding wheel,
On the outer peripheral surface of the grinding wheel layer of the grinding wheel, so that the grooves extending in the circumferential direction, a plurality at intervals in the rotation axis direction of the own kicked set,
The grinding wheel is composed of a splittable assembly in which a plurality of divided grinding wheels are stacked and fixed by bolting in the direction of the rotation axis. The divided grinding wheel includes a divided grinding wheel having a metal divided wheel main body and the grinding wheel layer formed narrower than the width of the divided grinding wheel so that the groove is formed therebetween. and wherein the a, centerless grinding method of the shaft member. A centerless grinding method for a shaft member using a grinding wheel whose grinding wheel layer is composed of a diamond grinding wheel,
A centerless grinding method for a shaft member, characterized in that a groove extending spirally around its rotation axis is provided on the outer peripheral surface of the grinding wheel layer of the grinding wheel.   The centerless grinding method for a shaft member according to claim 1, wherein the groove has a width smaller than an outer diameter of the shaft member after grinding. The grinding wheel is composed of a splittable assembly formed by stacking and fixing a plurality of divided grinding wheels in the rotational axis direction, and the grinding wheel is overlapped between the adjacent divided grinding wheels in the rotational axis direction. The split grinding wheel includes a split grinding wheel having a metal split wheel main body and the grinding wheel layer formed narrower than the width on the outer peripheral surface thereof so that a groove is formed. The centerless grinding method of the shaft member according to claim 2 .   The manufacturing method of a circular shaft member including the grinding process using the centerless grinding method of a shaft member of any one of Claims 1-4.   6. The method of manufacturing a circular shaft member according to claim 5, wherein a shape of a cross section of the shaft member before grinding is a polygon or a non-circular shape.   The method for manufacturing a circular shaft member according to claim 5, wherein the shaft member is mainly composed of ceramic.

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