JP2016129914A - Polishing body for screw shaft and its segment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing body for a screw shaft which can be easily manufactured, and can uniformly and accurately polish a male screw part of the screw shaft, and its segments.SOLUTION: A polishing body 5 for a screw shaft has a female screw-shaped polishing part, and polishes the screw shaft by rotating the screw shaft in a state that the female screw-shaped polishing part is engaged with a male screw part of the screw shaft. The female screw-shaped polishing part is constituted by laminating a plurality of flexible polishing sheets 15 having recessed circular edges 21a. This laminate is formed by superimposing the recessed circular edges 21a on one another in a center axial line Sdirection while making them displaced around the center axial line Swhich passes through a center of a virtual circle 20 with a trough diameter of the female screw-shaped polishing part as a diameter, and the laminated recessed circular edges 21a form a screw shaft insertion opening. Segments are obtained by dividing the polishing body 5 for the screw shaft into a plurality of pieces in a direction around the center axial line S.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a screw shaft polishing body for polishing a surface of a male screw portion of a screw shaft, and particularly to a screw shaft polishing body formed by laminating a plurality of polishing sheets and a segment thereof.

  Conventionally, for example, a single screw thread or a plurality of threads are used to accurately finish a screw shaft having a male thread portion formed on the outer peripheral surface of a shaft body such as a ball screw, a screw gauge, or a tap. There is known a grinding method in which a male screw surface of a screw shaft is ground using a grindstone having a thread (see, for example, Patent Documents 1 to 3).

  However, in the above grinding method using a grindstone, in order to grind the surface of the male screw portion of the screw shaft with high accuracy, the screw thread of the grindstone itself must be formed with high accuracy according to the shape of the male screw portion targeted by the screw shaft. Therefore, when manufacturing a grindstone, an advanced processing technique is required, and there is a problem that it cannot be easily manufactured.

Then, although the original grinding | polishing object is different, it is possible to grind the external thread part of a screw shaft using the gear grinding | polishing body (refer patent document 4) which laminates | stacks a flexible grinding | polishing sheet | seat.
However, in this gear polished body, since the bulging portion of the polishing sheet has a convex arc shape, the region where the bulging portion is superimposed on the male screw portion is narrow, and the bulging portion is bent in accordance with the surface shape of the male screw portion. Even so, the contact between the bulging portion and the male screw portion is close to a line contact, and there is a problem that there is a risk of non-uniform and inaccurate polishing.

Japanese Patent Laid-Open No. 5-138438 JP-A-10-296537 JP 2010-284796 Japanese Patent No. 5450870

  The present invention has been made in view of the above-described problems, and provides a screw shaft polishing body and a segment thereof that can be easily manufactured and can uniformly and accurately polish a male screw portion of a screw shaft. It is for the purpose.

In order to achieve the above object, a threaded shaft polishing body according to the first invention comprises:
A screw shaft insertion hole into which a screw shaft as an object to be polished is formed by forming a male screw portion on the outer peripheral surface of the shaft main body, and formed on an inner peripheral surface of the screw shaft insertion hole, and is engaged with the male screw portion. A female threaded polishing part, and the male threaded part is polished by the female threaded polishing part by rotating the screw shaft in a state where the male threaded part and the female threaded polishing part are engaged with each other. An abrasive body for a screw shaft,
A screw shaft insertion opening is formed which has a concave arc edge portion of a concave arc shape located radially inward from a virtual circle whose diameter is the valley diameter of the female thread-shaped polishing portion, and which constitutes the screw shaft insertion hole. A plurality of flexible polishing sheets, and overlapping the polishing sheets in the direction of the central axis while shifting the concave arc edges of the polishing sheets around a central axis passing through the center of the virtual circle. The female thread-like polishing portion is configured.

  In the first invention, the contour shape of the predetermined angle range around the center of the virtual circle in the screw shaft insertion opening is such that the distance between the point on the contour line and the center of the virtual circle is 1 of the male screw portion. It is preferable that the distance is determined so as to coincide with the distance between the contact point between the male threaded portion and the female thread-like polished portion in the pitch section and the central axis (second invention).

Next, the segment of the abrasive body for a screw shaft according to the third invention is:
The threaded shaft abrasive body according to the first or second aspect of the present invention comprises a portion divided into a plurality of portions in the direction around the central axis.

  According to the abrasive body for a screw shaft of the first invention, the concave arc edge portion of the polishing sheet is superimposed on the male screw portion by engagement of the external thread portion and the internal thread-like abrasive portion of the screw shaft, and the concave arc edge portion is recessed. Since it has an arc shape, the area where the concave arc edge is superimposed on the male thread is wide, and the concave arc edge bends according to the surface shape of the male thread so that the concave arc edge fits the male thread. Polishing is performed in a contacted state, and the external thread portion of the screw shaft can be uniformly and accurately polished. Moreover, since the concave arc edge part which comprises a female thread-like grinding | polishing part bends according to the surface shape of the external thread part of a screw shaft, it becomes unnecessary to shape | mold a female thread-like grinding | polishing part according to the surface shape of a male thread part with high precision. Can be easily manufactured.

  In addition, by adopting the configuration of the second invention, the male screw portion and the female screw-like polishing portion of the screw shaft can be engaged with each other with higher accuracy, and the polishing accuracy can be further improved.

  Further, according to the segment of the threaded shaft abrasive body of the third aspect of the invention, the threaded shaft abrasive body according to the first aspect of the invention or the second aspect of the invention is composed of a plurality of parts divided in the direction around the central axis. The peripheral device such as a holder for holding the segment is of course the first invention or the second invention, as well as the same effect as the threaded shaft abrasive body of the first invention or the second invention. There is an advantage that a smaller device than a peripheral device such as a holder for holding the screw shaft polishing body according to the present invention is sufficient.

FIG. 1 is a view showing a polishing operation for polishing a ball screw by a screw shaft polishing apparatus using a screw shaft polishing body according to an embodiment of the present invention, and FIG. ) Is a state diagram in which one end portion of the ball screw is being polished, (c) is a state diagram in which an intermediate portion of the ball screw is being polished, and (d) is a state diagram in which the other end portion of the ball screw is being polished. is there. FIG. 2 is a cross-sectional view taken along line AA in FIG. 3 is a cross-sectional view taken along line BB in FIG. FIG. 4 is an exploded perspective view of the threaded shaft abrasive body of the present embodiment. FIG. 5 is a view showing a polishing sheet constituting the screw shaft polishing body of the present embodiment, wherein (a) is a front view, (b) is a side view, and (c) is a rear view. FIG. 6 is an enlarged view of a portion C in FIG. FIG. 7 is a view for explaining the contour shape of the screw shaft insertion opening of the polishing sheet. FIG. 8 is a view showing another example of the polishing sheet, in which (a) is a front view, (b) is a side view, and (c) is a rear view. FIG. 9 is a view for explaining the contour shape of the screw shaft insertion opening of the polishing sheet for constituting the two female thread-like polishing portions. FIG. 10 is a view for explaining the contour shape of the screw shaft insertion opening of the polishing sheet for constituting the three female thread-like polishing portions. It is a side view which shows the segment of the abrasive body for screw shafts of this embodiment.

  Next, specific embodiments of a threaded shaft abrasive body and a segment thereof according to the present invention will be described with reference to the drawings. In the following, a ball screw will be described as an example of a screw shaft to be polished. However, the present invention is not limited to this, and a screw shaft in a form such as a screw gauge or a tap can also be a polishing target. It is.

<Description of screw shaft polishing device>
A screw shaft polishing apparatus 1 shown in FIGS. 1A to 1D includes a chuck device 2 disposed on the negative side of the X axis extending in the left-right direction in FIG. And a saddle 3 disposed on the positive direction side of the Y axis perpendicular to the X axis.
Chuck device 2 is for rotating the ball screw 4 in the axial S ₁ about in a state of gripping the end portion of the ball screw 4 male thread portion 4b on the outer circumferential surface of the shaft body 4a is formed, the saddle 3 The screw shaft polishing body 5 for polishing the ball screw 4 is supported via the polishing body holder 6 and is freely movable in the positive and negative directions of the X axis.

<Description of abrasive body for screw shaft>
As shown in FIGS. 2 and 3, the screw shaft polishing body 5 includes a screw shaft insertion hole 10 into which the ball screw 4 can be inserted. On the inner peripheral surface of the screw shaft insertion hole 10, a female thread-like polishing portion 11 that can be engaged with the male screw portion 4 b of the ball screw 4 is formed. The female screw-like polishing portion 11 is connected to the male screw portion of the ball screw 4. while remaining engaged in 4b, as shown in FIG. 1 (b) ~ (d) , by rotating the ball screw 4 in the axial S ₁ about the chuck device 2, the external thread portion in the female screw-like polishing section 11 4b can be polished.

As shown in FIG. 4, the screw shaft polishing body 5 is formed by laminating a plurality of flexible polishing sheets 15.
As shown in FIGS. 5 (a) to 5 (c), the polishing sheet 15 has a base material 16 and an adhesive layer on the entire surface of one side of the base material 16 (left side in FIG. 5 (b)). And a polishing layer 17 formed by adhering an abrasive. Note that the polishing layer 17 may be formed on both surfaces of the substrate 16.
Here, as shown in FIG. 5 (c), the base material 16 is concentric with a virtual circle 20 whose diameter is the valley diameter D ₁ (see FIG. 3) of the female thread-like polishing portion 11, and the virtual circle is formed. The screw shaft insertion hole 10 (see FIGS. 2 and 3) has an outer shape defined by the outline of a circle having a diameter D ₂ larger than 20 (the outer diameter of the threaded shaft polishing body 5: see FIG. 3). The screw shaft insertion opening 21 to be formed is provided at the center, and constitutes the basic portion of the polishing sheet 15.

Here, as the base material 16, it can select suitably from the sheet material which has flexibility, For example, a cotton cloth, synthetic fiber cloth, a kraft paper, a nonwoven fabric, a metal net, a synthetic resin sheet etc. are used.
As an abrasive (abrasive grain) attached to the substrate 16, for example, at least one selected from diamond, CBN (cubic boron nitride), B ₄ C, Al ₂ O ₃ , SiO ₂ , and SiC. The thing which consists of is mentioned.
The adhesive layer for adhering the abrasive to the base material 16 is composed of a binder for adhering the abrasives and an adhesive for adhering the abrasive to the base material.
The binder for adhering the abrasives is appropriately selected from commonly used metals, electrodeposition, vitrified, resin, and the like.
As an adhesive for adhering the abrasive to the base material, glue or synthetic resin is used. Examples of main synthetic resins used include polyimide resins, phenol resins, and epoxy resins. A filler such as calcium carbonate may be blended.

<Description of screw shaft insertion opening>
As shown in FIG. 5 (c), the screw shaft insertion opening 21 has a concave arc edge 21 a having a concave arc shape located radially inward from the virtual circle 20 concentric with the center of the base material 16. doing.

  Further, the contour shape of the screw shaft insertion opening 21 will be described in detail below with reference to FIGS.

First, as shown in FIG. 6, with determining the X-axis in FIG. 1 (c) the same manner so as to coincide with the central axis line S ₂ passing through the center point O of the virtual circle 20 (see FIG. 5 (c)) The positive direction of the Y-axis is determined in a direction perpendicular to the X-axis and toward the engagement position between the male screw portion 4b of the screw shaft 4 and the female screw-like polishing portion 11.
Then, with respect to the contact point with the female thread-like polishing part 11 in one pitch section of the male screw part 4b, the contact point between the top of the thread on the one side (left side in FIG. 6) and the female thread-like polishing part 11 in the male screw part 4b is defined as a. The coordinates of the point a are (X _a , Y _a ), the contact point between the valley bottom of the male screw portion 4b and the female screw-like polished portion 11 is b, and the coordinates of this point b are (X _b , Y _b ) An arbitrary contact point between the male threaded portion 4b and the female thread-like polished portion 11 between a and point b is c, and the coordinates of this point c are ( _Xc , _Yc ), and the other side of the male threaded portion 4b (FIG. 6). The contact point between the top of the thread on the right side) and the female thread-like polished part 11 is d, and the coordinates of this point d are (X _d , Y _d ), and the male thread 4b and female thread between the point b and the point d to any point of contact with Jo polishing unit 11 e, the coordinates of this point e and _(X e, _{Y e)} , The distance between each point and the center axis _{S 2} of the points a~ point e can be represented by each point Y coordinate _(Y a to Y _e).

Next, as shown in FIG. 7, the center point O of the imaginary circle 20 is set as the origin so as to go to the engagement position between the male screw portion 4 b of the screw shaft 4 and the female screw-like polishing portion 11 on the plane of the polishing sheet 15. A Y-axis is defined, and a Z-axis perpendicular to the Y-axis is defined. An arbitrary point P on the contour line of the screw shaft insertion opening 21 is set to a distance r from the center point O and a deviation angle θ from the Y-axis. Set polar coordinates in pairs.
And when theta is 0 °, r is _D 1/2: is a _{(D 1} root diameter of the female screw-like polishing section 11), when theta of, for example 60 °, r is a _{Y a,} theta is 0 ° In the range of greater than 60 °, r is gradually decreased from D _1/2 to approach Y _a, and in the range of θ greater than 60 ° and less than 180 °, r is Y _c, and θ is 180 ° , r is a _{Y b,} theta is the r is _{Y e} is in a range of less than 300 ° larger than 180 °, when theta is 300 °, r is a _{Y d,} theta is greater than 360 ° than 300 ° the range, r is gradually increased so as to approach the D _1/2 from Y _d.

As shown in FIG. 7, the contour shape in a predetermined angle range (for example, an angle range in which θ is 60 ° to 300 °) around the center point O of the virtual circle 20 in the screw shaft insertion opening 21 is on the contour line. The relationship between the distance r between the point P and the center point O of the virtual circle 20 is the distance (Y _{a to} Y) between the contact points a to e and the center axis S ₂ in one pitch section of the male screw portion 4b shown in FIG. _e ) It is determined to coincide with the relationship. Thereby, the external thread part 4b and the internal thread-like grinding | polishing part 11 can be engaged with high precision, and grinding | polishing precision can be raised more.

In the present embodiment, in order to position them abrasive sheet 15 in the state of shifting the concave Koen portion 21a at a plurality of abrasive sheet 15 by a predetermined angle from each other around the central axis line S _2, as shown in FIG. 7 The outer peripheral edge of the polishing sheet 15 has a first notch 22a at an angular position of, for example, θ = 0 ° around the center point O, and a second notch 22b at an angular position of θ = 10 °, respectively. Is provided. For example, in one polishing sheet 15 and the other polishing sheet 15 that are overlapped with each other, the first notch 22a of one polishing sheet 15 and the second notch 22b of the other polishing sheet 15 are aligned. it is thus possible to position the one abrasive sheet 15 and the other abrasive sheet 15 around the central axis S ₂ in a state shifted 10 ° from each other.

<Description of Method for Manufacturing Screw Shaft Polishing Body>
As shown in FIG. 4, the screw shaft polishing body 5 configured as described above has a structure in which all the polishing layers 17 of the plurality of polishing sheets 15 are oriented in the same direction. shifting each other concave Koen portion 21a around the central axis S ₂ is prepared by superimposing them abrasive sheet 15 S in _two directions its central axis.

That is, when the other polishing sheet 15 is overlaid on one polishing sheet 15, the first notch 22 a of one polishing sheet 15 and the second notch 22 b of the other polishing sheet 15 are aligned. Then, the plurality of polishing sheets 15 are sequentially overlapped. Thus, a plurality of abrasive sheet 15, the positioning in the position each other of the concave Koen portion 21a is shifted by a predetermined angle around the central axis S ₂ (10 ° in this example) is superimposed in a state of being made become.

The screw shaft polishing body 5 formed by laminating the plurality of polishing sheets 15 as described above is maintained by the polishing body holder 6 to maintain its shape.
Here, the polishing body holder 6 is composed of a pair of ring plates 6a and required bolts 6b. The pair of ring plates 6a sandwich the screw shaft polishing body 5 from both ends, and the ring plates 6a are connected to the required bolts 6b. By tightening at, the laminated state of the plurality of polishing sheets 15 is firmly maintained, and the shape of the ball screw 4 can be maintained and withstand the polishing operation.
It should be noted that the laminated state of the plurality of polishing sheets 15 can also be firmly held by fixing the adjacent polishing sheets 15 in the plurality of polishing sheets 15 with fixing means such as an adhesive, and the polishing body holder is not necessarily required. 6 is not required.

<Description of ball screw polishing operation>
Next, the polishing operation of the ball screw 4 using the screw shaft polishing body 5 will be described mainly with reference to FIG.

First, as shown in FIG. 1A, the chuck device 2 grips one end of the ball screw 4 and the other end is a free end so that the ball screw 4 is in a cantilevered state, and the abrasive holder 6 The polishing body 5 for the screw shaft in the state of being held by the polishing member 17 so that the polishing layer 17 (see FIGS. 5A and 5B) of the polishing sheet 15 is directed toward one end side (the negative direction side of the X axis) of the ball screw 4. Attach to saddle 3.
Next, as shown in FIG. 1B, the saddle 3 is moved to the negative direction side of the X axis so that the ball screw 4 is inserted into the screw shaft insertion hole 10 (see FIG. 2). The saddle 3 is stopped at a position near the one end of the ball screw 4 in a state where 4 is inserted into the screw shaft insertion hole 10. Then, a pressing force is applied to the negative direction side of the Y-axis by the saddle 3 so that the male screw portion 4b of the ball screw 4 and the female screw-like polishing portion 11 of the screw shaft polishing body 5 are engaged with each other. , The ball screw 4 is rotated around the axis S ₁ by the operation of the chuck device 2. The rotation at this time is equivalent to the rotation in the direction of loosening the bolt with respect to the nut, for example, assuming that the ball screw 4 is replaced with a bolt and the screw shaft polishing body 5 is replaced with a nut screwed into the bolt.

  Due to the rotational movement of the ball screw 4, the screw shaft polishing body 5 is moved together with the saddle 3 by the thrust applied from the male screw portion 4 b to the female screw-like polishing portion 11 as shown in FIGS. The ball screw 4 is fed to the other end side, whereby the male screw portion 4b is rubbed against the female screw-shaped polishing portion 11 from the portion near the one end portion of the ball screw 4 to the other end portion, so that the entire ball screw 4 is It will be polished. Further, when the feeding operation of the threaded shaft abrasive body 5 by the ball screw 4 proceeds, the threaded shaft abrasive body 5 is finally detached from the ball screw 4 and the engagement between the male threaded portion 4b and the female threaded polished portion 11 is released. This completes one cycle of the polishing operation.

  The above-described polishing operation is performed using a part of the circumferential direction of the female thread-shaped polishing portion 11 in the threaded shaft polishing body 5, and the portion of the female thread-shaped polishing portion 11 that engages with the male thread portion 4b is determined. By gradually shifting in the circumferential direction of the female thread-like polishing portion 11, polishing is always performed on a new polishing surface, and the polishing performance when new can be maintained for a long time.

<Description of effects>
According to the threaded shaft abrasive body 5 of the present embodiment, the concave arc edge 21a of the polishing sheet 15 is superimposed on the male thread part 4b by the engagement of the male thread part 4b of the ball screw 4 and the female thread-like grinding part 11, Since the concave arc edge 21a has a concave arc shape, a region where the concave arc edge 21 is superimposed on the male screw portion 4b (region with a mesh pattern indicated by reference numeral “30” in FIG. 2) is wide. When the male screw portion 4b is rubbed against the female screw-like polishing portion 11 by the thrust applied from the male screw portion 4b to the female screw-like polishing portion 11 as the ball screw 4 rotates, the concave arc edge 21a becomes the surface shape of the male screw portion 4b. By bending together, the polishing is performed in a state in which the concave arc edge 21a is in close contact with the male screw portion 4b, and the male screw portion 4b of the ball screw 4 can be uniformly and accurately polished. Moreover, since the concave arc edge 21a which comprises the internal thread-shaped grinding | polishing part 11 bends according to the surface shape of the external thread part 4b of the ball screw 4, it is highly accurate according to the surface shape of the external thread part 4b. Therefore, it can be easily manufactured.

  The threaded shaft abrasive body of the present invention has been described based on one embodiment. However, the present invention is not limited to the structure described in the above embodiment, and the structure is appropriately set within the scope of the invention. Can be changed.

For example, although detailed explanation by illustration is omitted, in the above-described threaded shaft polishing body 5, a spacer for providing a predetermined gap is provided between the polishing sheets 15 adjacent to each other in the plurality of polishing sheets 15. It may be. By doing so, the degree of bending of the concave arc edge 21a of the polishing sheet 15 can be easily adjusted by adjusting the thickness, diameter, number, etc. of the spacers.
Further, by adhering adjacent abrasive sheets 15 with an adhesive or the like and adjusting the adhesion area, the degree of bending of the concave arc edge 21a of the abrasive sheet 15 can be easily adjusted. For example, when the adjacent abrasive sheets 15 are bonded together or when the portions near the inner periphery including the concave arc edge 21a in the adjacent abrasive sheets 15 are bonded to each other, the concave arc edge 21a is bent. The internal thread-like polishing part 11 can be hardened by this, and the adhesion area of the part near the inner periphery of the polishing sheet 15 including the concave arc edge 21a is reduced from the inner peripheral side toward the outer peripheral side. Accordingly, the amount of bending can be increased accordingly, and the hardness of the female threaded polishing portion 11 can be reduced.

  Further, in the polishing sheet 15 in the above embodiment, as shown in FIGS. 5A to 5C, the polishing layer 17 is provided on the entire surface of one side of the base material 16 (left side in FIG. 5B). Although it is provided, as shown in 8 (a) to (c), between the concave arc edge 21 a and the virtual circle 20 on the surface of one side of the base material 16 (left side in FIG. 8B). The polishing layer 17 may be provided only in this part. By doing so, the polishing layer 17 is provided only in the portion that is substantially in contact with the male screw portion 4b, and the amount of abrasives and the like used can be greatly reduced while providing the necessary polishing function. Further, since the polishing layer 17 is not provided in a portion other than the portion between the concave arc edge 21a and the virtual circle 20 in the polishing sheet 15, the polishing layer 17 is provided on the entire surface of the base material 16. In comparison, the polishing sheet 15 is flexed more flexibly, the concave arc edge 21a can be brought into close contact with the male screw portion 4b, and more uniform and highly accurate polishing can be realized.

  In the above embodiment, the example in which the female thread-like polishing portion 11 has a single thread is shown, but instead of the polishing sheet 15, the circumferential direction around the center point O as shown in FIG. If a polishing sheet 15A in which two concave arc edges 21a are arranged at equal angular intervals is used, the internal thread-like polishing part 11 has a double thread, and the circumference around the center point O as shown in FIG. If a polishing sheet 15B in which three concave arc edges 21a are arranged at equiangular intervals in the direction is used, a plurality of concave arc edges 21a are formed such that the internal thread-like polishing section 11 has a triple thread. By dispersively arranging in the circumferential direction around the center point O, a plurality of female thread-like polishing portions 11 can be configured.

Here, in the polishing sheet 15A shown in FIG. 9, an arbitrary point P on the contour line of the screw shaft insertion opening 21 is set to the distance r from the center point O and the deflection angle θ from the Y axis in the manner described above. setting the polar coordinates in terms of the set, when θ is 0 °, r is D _1/2: is a (D 1 root diameter of the female screw-like polishing section), when θ is 30 °, r is a Y _a , Θ is gradually decreased from D _1/2 to approach Y _a in the range of greater than 0 ° and less than 30 °, and r is Y _{c in} the range of θ greater than 30 ° and less than 90 °, θ When r is 90 °, r is Y _b, and when θ is greater than 90 ° and less than 150 °, r is Y _e, and when θ is 150 °, r is Y _d and θ is 180 °. when, r is the _D 1/2, in the range θ is greater than 180 ° than 0.99 °, increasing as r approaches _D 1/2 from _{Y d} It has been. Further, when θ is 210 °, r is set to Y _a, and in the range where θ is greater than 180 ° and less than 210 °, r is gradually decreased from D _1/2 to approach Y _a , and θ is less than 210 °. R is Y _{c in} the range of greater than 270 °, r is Y _b when θ is 270 °, r is Y _{e in} the range of greater than 270 ° and less than 330 °, and θ is 330 When the angle is °, r is Y _d, and in a range where θ is greater than 330 ° and less than 360 °, r is gradually increased from Y _d to approach D _1/2 .

Further, by setting the polar coordinates also in the abrasive sheet 15B as shown in FIG. 10, when theta is 0 °, r is the D _1/2, when theta is 20 °, r is a Y _a, theta When the angle is greater than 0 ° and less than 20 °, r is gradually decreased from D _1/2 to approach Y _a , and when θ is greater than 20 ° and less than 60 °, r is Y _c, and θ is 60 When r is r, Y is _b . When θ is greater than 60 ° and less than 100 °, r is Y _e . When θ is 100 °, r is Y _d and θ is 120 °. , r is the _D 2/2, _θ is in the range of less than 120 ° larger than 100 °, r is gradually increased so as to approach the _D 1/2 from _{Y d.} In addition, when θ is 140 °, r is Y _a, and in the range where θ is greater than 120 ° and less than 140 °, r is gradually decreased from D _1/2 to approach Y _a , and θ is less than 140 °. In the range of greater than 180 °, r is Y _c . When θ is 180 °, r is Y _b . In the range of θ greater than 180 ° and less than 220 °, r is Y _e and θ is 220. when °, r is a _{Y d,} when θ is 240 °, r is the _D 2/2, in the range θ is greater than 240 ° than 220 °, r is the _D 1/2 from _{Y d} It is gradually increased to approach. Further, when θ is 260 °, r is set to Y _a, and in the range where θ is greater than 240 ° and less than 260 °, r is gradually decreased from D _1/2 to approach Y _a , and θ is less than 260 °. In a large range of less than 300 °, r is Y _c . When θ is 300 °, r is Y _b . In a range of θ greater than 300 ° and less than 340 °, r is Y _e and θ is 340. When the angle is °, r is Y _d, and in a range where θ is greater than 340 ° and less than 360 °, r is gradually increased from Y _d so as to approach D _1/2 .

Moreover, in the said embodiment, although the example of an aspect which grind | polishes the ball screw 4 using the whole grinding | polishing body 5 for screw shafts was shown, as FIG. _{2 A} segment 35 composed of one part divided into a plurality of parts (for example, four parts) in a direction around (a straight line perpendicular to the paper surface passing through the center point of the virtual circle 20 (see FIG. 5) indicated by the symbol O in FIG. 11). Alternatively, the ball screw 4 may be polished. By doing so, the same effect as the screw shaft polishing body 5 can be obtained, and the saddle for holding the segment 35 and its supporting structure (not shown) can be used for polishing the screw shaft. There is an advantage that a smaller one than the saddle 3 holding the body 5 and its supporting structure (not shown) is sufficient.

  In the polishing sheet 15, the polishing layer 17 is provided on the surface of the substrate 16. However, the present invention is not limited to this. For example, an abrasive (abrasive grain) is kneaded into a synthetic resin into a sheet shape. You may use what shape | molded and what embed | buried an abrasive grain integrally in a sheet-like metal plate.

Further, in the polishing sheet 15, an example in which the polishing layer 17 is provided only on one surface of the base material 16 has been shown. In this case, in order to polish both screw threads of the male screw portion 4 b, It is necessary to once release the engaged state of the shaft polishing body 5 and then change the mounting direction of the screw shaft polishing body 5 with respect to the saddle 3.
Therefore, in the polishing sheet 15, the polishing layer 17 is also provided on the other surface of the base material 16, that is, the polishing layer 17 is provided on both the front and back surfaces of the base material 16. Thus, both screw threads of the male thread portion 4b can be polished by forward and reverse rotation of the screw shaft 4 with a single chuck without releasing the engaged state, and work efficiency can be improved.

  The abrasive body for a screw shaft and the segment thereof according to the present invention have characteristics that it can be easily manufactured and can polish the external thread portion of the screw shaft uniformly and accurately, and therefore requires high accuracy. It can be suitably used for surface polishing of a male screw portion of a screw shaft such as a ball screw, a screw gauge, or a tap.

DESCRIPTION OF SYMBOLS 1 Screw shaft grinding | polishing apparatus 2 Chuck apparatus 3 Saddle 4 Screw shaft 4a Shaft main body 4b Male thread part 5 Screw shaft grinding | polishing body 10 Screw shaft insertion hole 11 Female thread-shaped grinding | polishing part 15 Polishing sheet 20 Virtual circle 21 Screw shaft insertion opening 21a Concave Arc edge 35 segments

Claims (3)

A screw shaft insertion hole into which a screw shaft as an object to be polished is formed by forming a male screw portion on the outer peripheral surface of the shaft main body, and formed on an inner peripheral surface of the screw shaft insertion hole, and is engaged with the male screw portion. A female threaded polishing part, and the male threaded part is polished by the female threaded polishing part by rotating the screw shaft in a state where the male threaded part and the female threaded polishing part are engaged with each other. An abrasive body for a screw shaft,
A screw shaft insertion opening is formed which has a concave arc edge portion of a concave arc shape located radially inward from a virtual circle whose diameter is the valley diameter of the female thread-shaped polishing portion, and which constitutes the screw shaft insertion hole. A plurality of flexible polishing sheets, and overlapping the polishing sheets in the direction of the central axis while shifting the concave arc edges of the polishing sheets around a central axis passing through the center of the virtual circle. A screw shaft polishing body comprising the female thread polishing portion.   The contour shape of the predetermined angle range around the center of the virtual circle in the screw shaft insertion opening is such that the distance between the point on the contour line and the center of the virtual circle is the male screw in one pitch section of the male screw portion. 2. The threaded shaft abrasive body according to claim 1, wherein the threaded shaft abrasive body is determined so as to coincide with a distance relationship between a contact point between the portion and the female thread-like polished portion and the central axis. 3. A segment of a threaded shaft abrasive body, comprising a portion obtained by dividing the threaded shaft abrasive body according to claim 1 or 2 into a plurality of parts in a direction around the central axis.

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