JP2023075770A - Screw shaft polishing device and screw shaft polishing method - Google Patents

Abstract

To provide a screw shaft polishing device that can evenly and accurately polish a male screw part of a screw shaft without causing any hindrance on polishing operation.SOLUTION: A screw shaft polishing device 1 for polishing a male screw part 100b of a ball screw 100 includes: a pair of polishing bodies 3 including a flexible female screw-like polishing part that engages the male screw part 100b and is disposed so as to hold the ball screw 100 from both sides; pressing means 7 for pressing the pair of polishing bodies 3 to the ball screw 100; and rotation means 5 for rotating the ball screw 100.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a screw shaft polishing apparatus and a screw shaft polishing method for polishing a male thread portion of a screw shaft.

For example, ball screws, screw gauges, taps, etc., which have a male threaded portion on the outer peripheral surface, have a flexible female threaded grinding portion in order to achieve high-quality finishing with high accuracy. There is one in which a screw shaft polishing body is used to polish the surface of the male thread portion of a screw shaft (see, for example, Patent Document 1).

The screw shaft grinding body according to Patent Document 1 has a screw shaft insertion hole into which a screw shaft can be inserted, and a female screw grinding portion is formed on the inner peripheral surface of the screw shaft insertion hole. Polishing using this screw shaft polishing body is performed by inserting the screw shaft to be polished into the screw shaft insertion hole and engaging the female threaded polishing portion so as to press against the male threaded portion of the screw shaft from one side in the direction perpendicular to the screw shaft. This is done by rotating the screw shaft in a state where the When the screw shaft is rotated, the screw shaft grinding body is fed in the axial direction of the screw shaft by a screw feeding thrust applied from the male threaded portion of the screw shaft to the female threaded grinding portion of the screw shaft grinding body. At this time, polishing is performed by rubbing the female threaded polishing portion against the male threaded portion while the female threaded polishing portion bends according to the surface shape of the male threaded portion.

JP 2016-129914 A

In the polishing using the screw shaft polishing body according to Patent Document 1, the ridges of the female screw-shaped polishing part of the screw shaft polishing body are deeper than the grooves between the adjacent thread ridges of the male thread part of the screw shaft. Polishing may be performed in a state in which a gap is formed between the two without entering, and unevenness may occur in the polishing finish. If the pressing force of the female threaded ground portion against the male threaded portion of the screw shaft is increased, the ridges of the female threaded ground portion enter deeply into the grooves of the male threaded portion, and grinding is performed in a state in which both are in close contact with each other. It is thought that spots do not occur in the polishing finish. However, the pressing force applied to the screw shaft from the screw shaft grinder is applied only from one side of the screw shaft. there is a risk of

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a screw shaft polishing apparatus capable of polishing a male thread portion of a screw shaft uniformly and accurately without interfering with the polishing operation, and a screw shaft polishing apparatus. The purpose is to provide a method.

The characteristic configuration of the screw shaft grinding apparatus according to the present invention for solving the above problems is as follows:
A screw shaft polishing device for polishing a male thread portion of a screw shaft,
a pair of polishing bodies having a flexible female-threaded polishing portion that engages with the male-threaded portion and arranged to sandwich the screw shaft from both sides;
pressing means for pressing the polishing body against the screw shaft;
a rotating means for rotating the screw shaft;
It is to prepare

According to the screw shaft polishing apparatus of this configuration, the pair of polishing bodies are pressed against the screw shaft by the pressing means in a state in which the flexible female thread polishing portion is engaged with the male thread portion of the screw shaft, and the screw shaft rotates. rotated by means. As a result, the ridges of the female threaded polishing portion are deeply inserted into the grooves of the male threaded portion, and polishing is performed in a state in which both are in close contact with each other. At this time, between the screw shaft and the pair of grinding bodies, the pressing force of the female threaded grinding portion against the male threaded portion is applied from both sides of the screw shaft. There is no problem with the polishing operation. Therefore, the external thread portion of the screw shaft can be ground uniformly and accurately.

In the screw shaft polishing device according to the present invention,
The polishing body includes a plurality of polishing sheets arranged in a laminated state in the axial direction of the screw shaft,
The internally threaded polishing portion is formed by superimposing the polishing sheets so as to form a screw shape,
It is preferable to further include swinging means for swinging the polishing body around the screw shaft.

In the screw shaft polishing apparatus having this configuration, the polishing body includes a plurality of polishing sheets arranged in a laminated state in the axial direction of the screw shaft, and the female threaded polishing portion includes a plurality of polishing sheets that are superimposed so as to form a screw shape. formed by When the internally threaded polishing portion formed in this manner rotates relative to the screw shaft, the threaded portion of the externally threaded portion of the screw shaft moves relative to the steps of the adjacent polishing sheets that are superimposed on each other. It has a first threaded surface in sliding contact and a second threaded surface in sliding contact while the threaded portion of the male threaded portion of the screw shaft moves relatively so as to climb the steps of the adjacent polishing sheets that are superimposed on each other. are doing.

In the case where the internally threaded ground portion has such a first thread surface and a second thread surface, when the screw shaft is rotated by the rotating means, the first thread surface has adjacent threads that overlap each other. Before crossing the step in the polishing sheet, the polishing sheet on the front side of the step contact with which the thread portion of the male thread portion contacts is pressed against the polishing sheet on the rear side of the step contact with which the thread portion of the male thread portion contacts after crossing the step. A pressing force is sequentially applied to adjacent superimposed abrasive sheets as the thread portion moves relative to the first thread surface to press the threads of the external thread portion with the abrasive sheets in closer contact with each other. part will be polished. On the other hand, on the second thread surface, the thread portion of the male thread portion is oriented in such a direction that the thread portion of the male thread portion bites between the abrasive sheet on the front side of crossing the step and the abrasive sheet on the rear side of crossing the step. A pressing force is applied to the polishing sheet on the front side of the step so as to separate the polishing sheet on the front side of the step from the polishing sheet on the rear side of the step. A grinding operation for grinding the thread portion of the male thread portion is performed in such a state that the sheets are pulled apart. For this reason, in the portion on one side and the other side in the male thread portion of the screw shaft, for example, the portion on the one side in the axial direction contacts the first thread surface, When the side portion contacts the second thread surface, the portion on the one axial side is ground well, while the portion on the other axial side is ground with the first thread surface. It will not be done as well. As a result, a difference in polishing accuracy occurs between the portion on one side and the portion on the other side of the screw thread portion of the male thread portion of the screw shaft. In other words, there is a difference in polishing accuracy between the axially one side portion and the other side portion of the groove portion formed between the adjacent thread portions in the male thread portion of the screw shaft. In view of such a difference in polishing accuracy, in order to polish the entire groove uniformly and accurately, the direction of the portion functioning as the first thread surface and the portion functioning as the second thread surface It is conceivable to change the setting of the pair of polishing bodies with respect to the screw shaft so as to replace the , and perform the polishing operation again. However, in this case, it takes time and effort to change the setting, and the time required for polishing is increased because the polishing is performed again.

Therefore, the screw shaft polishing apparatus of this configuration further includes swinging means for swinging the pair of polishing bodies around the screw shaft. As a result, the pair of grinding bodies are oscillated around the screw shaft by the oscillating means. The part where the polishing is performed is replaced according to the oscillation period of the pair of polishing bodies. As a result, it is equivalent to contacting the entire groove portion of the male thread portion of the screw shaft with the first thread surface capable of performing good grinding. Therefore, the setting of the pair of grinding bodies with respect to the screw shaft is changed so that the direction of the portion functioning as the first thread surface and the direction of the portion functioning as the second thread surface are exchanged, and then the grinding operation is performed again. Even if it is not performed, the entire groove can be uniformly and accurately polished, the labor for setting change can be saved, the time required for polishing can be shortened, and the polishing efficiency can be improved.

In the screw shaft polishing device according to the present invention,
The pressing means includes a pair of arm members having one end attached with the polishing body and the other end side being pivotally connected to each other. pressing against the screw shaft;
The rocking means is
a push/pull rod having one end connected to the arm member;
a crank connected to the other end of the push/pull rod;
including
It is preferable that the pushing/pulling rod is reciprocated by the rotation of the crank, thereby swinging the polishing body around the screw shaft via the arm member.

According to the screw shaft polishing apparatus of this configuration, the pair of arm members attached to one end of the pair of arm members whose other ends are pivoted to each other is applied with a force in a direction to bring the pair of arm members closer to each other. Since the grinding body is pressed against the screw shaft, the pressing force of the female thread grinding portion against the male thread portion can be applied equally from both sides of the screw shaft in the direction perpendicular to the axis. Furthermore, according to the screw shaft polishing apparatus of this configuration, the pair of arm members are rotated at a constant rotation angle around the screw shaft by the push/pull rod that is reciprocated by the rotation of the crank. A pair of polishing bodies attached to the member can be oscillated around the screw shaft at a constant amount of oscillation and at a constant oscillating period. By providing such pressing means and swinging means, the entire groove can be polished more uniformly and accurately.

Next, the characteristic configuration of the screw shaft grinding method according to the present invention for solving the above problems is as follows:
A screw shaft polishing method for polishing a male threaded portion of a screw shaft, comprising:
an arranging step of arranging a pair of polishing bodies having a flexible female-threaded polishing portion that engages with the male-threaded portion so as to sandwich the screw shaft from both sides;
a pressing step of pressing the polishing body against the screw shaft;
a rotating step of rotating the screw shaft;
to include

According to the threaded shaft grinding method of this configuration, in the arranging step, a pair of grinding bodies having a flexible female threaded grinding portion that engages with the male threaded portion are placed so as to sandwich the threaded shaft from both sides. Then, in the pressing step, the pair of grinding bodies are pressed against the screw shaft while the female threaded grinding portion is engaged with the male thread portion of the screw shaft, and in the rotating step, the screw shaft is rotated. As a result, the ridges of the female threaded polishing portion are deeply inserted into the grooves of the male threaded portion, and polishing is performed in a state in which both are in close contact with each other. At this time, between the screw shaft and the screw shaft grinder, the pressing force of the female thread grinding portion against the male thread portion is applied from both sides of the screw shaft. It does not bend and does not hinder the polishing operation. Therefore, the external thread portion of the screw shaft can be ground uniformly and accurately.

In the screw shaft polishing method according to the present invention,
The polishing body includes a plurality of polishing sheets arranged in a laminated state in the axial direction of the screw shaft,
The internally threaded polishing portion is formed by superimposing the polishing sheets so as to form a screw shape,
It is preferable that the polishing body is swung around the screw shaft during the rotation step.

According to the threaded shaft grinding method of this configuration, the rocking step of rocking the pair of grinding bodies configured as described above around the threaded shaft is performed. As a result, the portion functioning as the above-described first thread surface and the portion functioning as the above-described second thread surface of the pair of polishing bodies are exchanged according to the oscillation period of the pair of polishing bodies. become. As a result, it is equivalent to contacting the entire groove portion of the male thread portion of the screw shaft with the first thread surface capable of performing good grinding. Therefore, the setting of the pair of grinding bodies with respect to the screw shaft is changed so that the direction of the portion functioning as the first thread surface and the direction of the portion functioning as the second thread surface are exchanged, and then the grinding operation is performed again. Even if it is not performed, the entire groove can be uniformly and accurately polished, the labor for setting change can be saved, the time required for polishing can be shortened, and the polishing efficiency can be improved.

FIG. 1 is a schematic configuration diagram of a screw shaft polishing apparatus according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part taken along the line XX in FIG. 1(a). FIG. 3 is an explanatory diagram of a polishing body used in the screw shaft polishing apparatus of this embodiment. FIG. 4 is an exploded perspective view of a cylindrical polishing body. FIG. 5 is a diagram showing a polishing sheet that constitutes a cylindrical polishing body. FIG. 6 is a plan view showing the polishing operation. FIG. 7 is an explanatory diagram of the swinging process. FIG. 8 is a diagram showing a lamination state of a part of the polishing bodies.

The present invention will be described below with reference to the drawings. In the following embodiments, a ball screw will be described as an example of a screw shaft to be ground. However, the present invention is not intended to be limited to the embodiments described below or the configurations described in the drawings.

<Overall composition>
FIG. 1 is a schematic configuration diagram of a screw shaft polishing apparatus 1 according to one embodiment of the present invention. FIG. 1(a) is a plan view of the screw shaft polishing apparatus 1, and FIG. 1(b) is an enlarged view of part A in FIG. 1(a). A ball screw 100, which is a type of screw shaft, is to be polished by the screw shaft polishing apparatus 1 shown in FIG. 1(a). The ball screw 100 has a shaft body 100a and a male threaded portion 100b formed on the outer peripheral surface of the shaft body 100a. A screw shaft polishing device 1 is a device for polishing a male thread portion 100 b of a ball screw 100 , and includes a pair of polishing bodies 3 , rotating means 5 , pressing means 7 and swinging means 9 .

<Polish body>
FIG. 2 is a cross-sectional view of a main part taken along the line XX in FIG. 1(a). As shown in FIG. 2, the pair of grinding bodies 3 has a flexible female threaded grinding portion 10 that engages with the male threaded portion 100b of the ball screw 100. It is arranged so as to sandwich it from both sides.

FIG. 3 is an explanatory view of the grinding body 3 used in the screw shaft grinding device 1 of this embodiment. FIG. 3(a) is an exploded perspective view of the polishing body 3, and FIG. 3(b) is an explanatory diagram showing that the pair of polishing bodies 3 is composed of the tubular polishing body 20 portion. As shown in FIG. 3(a), the grinding body 3 has a central axis S2 passing through the axial direction of the ball screw 100 (the center point O of a virtual circle 30 described later (see FIGS. 5(a) and 5(c)) ₎ . direction) are arranged in a laminated state. The polishing sheet 15 is made of, for example, a flexible sheet material having a partial fan shape with a central corner portion notched and having a predetermined thickness. The internally threaded polishing portion 10 is formed in a predetermined portion of the plurality of polishing sheets 15, in this example, a portion between the inner peripheral position and the inner peripheral edge of the partial fan-shaped polishing sheet (to which an abrasive material 27 described later is attached). part) are overlapped so as to form a screw shape. A plurality of polishing sheets 15 are fixed by a fixing means such as an adhesive at required portions other than the portion that will become the internally threaded polishing portion 10 . As a result, the shape of the polishing body 3 is maintained.

As shown in FIG. 3(b), the pair of polishing bodies 3 are arranged so that the cylindrical polishing body 20 is positioned at the center point of an imaginary circle (see FIGS. 5(a) and (c)), which will be described later and is indicated by symbol O in the figure. Consists of any two parts (in this example, two parts in a symmetrical positional relationship with respect to the center point O) of the parts divided into a plurality of parts (e.g., 8 divisions) around a straight line that passes through and is perpendicular to the paper surface. It is Accordingly, the polishing sheet 15 constituting the polishing body 3 is composed of a part (1/8 part) of the later-described polishing sheet 25 constituting the cylindrical polishing body 20 . The cylindrical polishing body 20 has a screw shaft insertion hole 21 into which the ball screw 100 can be inserted. A shaped polishing portion 23 is formed. Accordingly, the internally threaded polishing portion 10 of the polishing body 3 is composed of the female threaded polishing portion 23 of the cylindrical polishing body 20 (1/8 portion).

FIG. 4 is an exploded perspective view of the cylindrical polishing body 20. FIG. As shown in FIG. 4, the cylindrical polishing body 20 includes a plurality of hollow circular polishing sheets 25 arranged in a laminated state in the direction of the central axis _S2 . The internally threaded polishing portion 23 is formed by stacking a plurality of polishing sheets 25 having the same structure and shape while shifting them by a predetermined angle in one direction around the central axis _S2 . More specifically, the internally threaded polishing portion 23 extends from a predetermined portion of the plurality of polishing sheets 25, which in this example is a hollow circular polishing sheet, from a position near the inner periphery (virtual circle 30 to be described later) to the inner peripheral edge ( The portion (the portion to which the abrasive material 27 described later is attached) between the recessed arc edge 33 (to be described later) is shifted in one direction around the central axis _S2 by a predetermined angle so as to form a screw shape. It is superimposed and formed. The plurality of polishing sheets 25 are fixed by a fixing means such as an adhesive agent at required portions other than the portions that will become the internally threaded polishing portions 23 . Thereby, the shape of the cylindrical polishing body 20 is maintained.

FIG. 5 shows a polishing sheet 25 that constitutes the cylindrical polishing body 20. As shown in FIG. 5(a) is a front view, FIG. 5(b) is a side view, and FIG. 5(c) is a rear view. As shown in FIGS. 5(a) to 5(c), the polishing sheet 25 is adhered to the base material 26 and a predetermined portion on one side (the left side in FIG. 5(b)) of the base material 26 via an adhesive. It is composed of an abrasive material 27 that is

As shown in FIG. 5(c), the substrate 26 is concentric with an imaginary circle 30 whose diameter is the root diameter _D1 of the internally threaded polished portion 23, and has a diameter _D2 (cylindrical shape) larger than the imaginary circle 30. The polishing sheet 25 has an outer shape defined by a circular outline of the outer diameter of the polishing body 20) and has a screw shaft insertion opening 31 forming the screw shaft insertion hole 21 (see FIG. 3) in the center. It forms the basis of

The base material 26 can be appropriately selected from sheet materials having flexibility, and examples thereof include cotton cloth, glass cloth, synthetic fiber cloth, kraft paper, nonwoven fabric, metal mesh, and synthetic resin sheet.

The abrasive (abrasive grains) 27 attached to the base material 26 is, for example, diamond, CBN (cubic boron nitride), B ₄ C, Al ₂ O ₃ , SiO ₂ , and SiC. One type is mentioned. Among these, diamond and CBN are preferred. Diamond and CBN are called cemented carbide grains, and the use of these cemented carbide grains can improve polishing efficiency. Here, the abrasive 27 is attached to the substrate 26 via an adhesive. The adhesive used here is composed of a bonding component that bonds the abrasives 27 together and an adhesive component that bonds the abrasives 27 to the substrate 26 . The bonding component that bonds the abrasives 27 together can be appropriately selected from commonly used metals, vitrified materials, resins, and the like. Glue, synthetic resin, or the like is used as an adhesive component for adhering the abrasive material 27 to the base material 26 . Main synthetic resins include polyimide resin, phenol resin, epoxy resin, and the like.

As shown in FIG. 5(c), the substrate 26 has a concave arcuate edge 33. As shown in FIG. The concave arc edge portion 33 is located radially inward from the virtual circle 30 concentric with the center of the base material 26 and forms part of the edge portion of the screw shaft insertion opening 31 . As shown in FIG. 5(a), the abrasive 27 is provided only on the portion between the concave arc edge 33 and the virtual circle 30 on the surface of one side of the substrate 26 (the left side in FIG. 5(b)). be done. By doing so, the abrasive material 27 is provided only on the portion that substantially contacts the male threaded portion 100b of the ball screw 100, and the entire one side surface of the base material 26 is provided with the necessary abrasive function. Compared to the case where the abrasive material 27 is provided, the amount of the abrasive material 27 and adhesive used can be greatly reduced. Further, since the polishing sheet 25 is not provided with the polishing material 27 except for the portion between the concave arc edge 33 and the imaginary circle 30, the polishing material 27 is provided on the entire surface of the base material 26. In comparison, the polishing sheet 25 (polishing sheet 15) bends more flexibly, so that the concave arc edge 33 (the edge of the partially fan-shaped polishing sheet 15) can be brought into closer contact with the male threaded portion 100b. , more uniform and high-precision polishing can be achieved.

Next, specific configurations of the rotating means 5, the pressing means 7, and the swinging means 9, which constitute the screw shaft polishing apparatus 1, will be described in order.

<Rotating Means>
As shown in FIG. 1A, the rotating means 5 includes a chuck device 51 arranged on the negative direction side of the X-axis extending in the left-right direction in the drawing, and a chuck device 51 facing the positive direction of the X-axis. and a tailstock 53 disposed on the side. The chuck device 51 rotates the ball screw 100 about the axis _S1 of the shaft body 100a while gripping one end of the ball screw 100. As shown in FIG. The tailstock 53 rotatably supports the other end of the ball screw 100 . Thus, in the rotating means 5, both ends of the ball screw 100 are stably supported by the chuck device 51 and the tailstock 53, and the chuck device 51 is operated to rotate the ball screw 100 around its axis _S1 . be able to.

<Pressing Means>
As shown in FIG. 2, the pressing means 7 includes a pair of arm members 61 and an extension coil spring 63 as a pressing force applying device.

<Arm member>
The pair of arm members 61 includes a pair of arm body portions 65 which are bent so as to bulge outward between one end side (lower end side) and the other end side (upper end side), and a pair of arm bodies. A pair of pad portions 67 attached to the lower end side of the portion 65 are provided.

Upper end sides of the pair of arm body portions 65 are pivoted to each other via a pivot shaft 70 . As a result, the pair of arm body portions 65 are connected to each other so as to be rotatable about the pivot shaft 70 , and the pair of arm members 61 are moved by rotating the pair of arm body portions 65 about the pivot shaft 70 . Can be opened and closed. A pair of pad portions 67 are rotatably connected to the lower end sides of the pair of arm body portions 65 via a pair of connecting pins 69 . A pair of polishing bodies 3 are fixed to the opposing surfaces of the pair of pad portions 67 with an adhesive or the like.

When the ball screw 100 is sandwiched by the pair of grinding bodies 3 from both sides in the direction perpendicular to the axis, the pair of arm main bodies 65 are provided so that the pair of grinding bodies 3 come into contact along the shape of the outer peripheral surface of the ball screw 100. On the other hand, the pair of pad portions 67 rotate via the pair of connecting pins 69, and the attitude of the pair of pad portions 67 with respect to the pair of arm body portions 65 changes. In this way, the pair of polishing bodies 3 can be brought into contact along the shape of the outer peripheral surface of the ball screw 100, and the female threaded polishing portion 10 of the polishing body 3 can be easily and reliably engaged with the male threaded portion 100b of the ball screw 100. can be combined. Further, for example, when a plurality of types of ball screws 100 having different outer diameters are treated as objects to be polished, even if the opening angle of the pair of arm members 61 changes, the ball screw 100 can be ground along the shape of the outer peripheral surface of the ball screw 100. A pair of polishing bodies 3 can be stably pressed against both sides of the .

<Pressing Force Applicator>
The tension coil spring 63 exerts a force in a direction to bring the pair of arm members 61 closer to each other, so that the pressing force for pressing the pair of polishing bodies 3 against the ball screw 100 is applied to the pair of arm main bodies 65 and the pair of pad portions. It functions as a pressing force applicator that applies a pressing force to the pair of polishing bodies 3 via 67 . In this way, the ball screw 100 can be sandwiched between the pair of polishing bodies 3 .

The extension coil spring 63 is arranged inside the pair of arm body portions 65 . Both ends of the tension coil spring 63 are connected to upper portions of the pair of arm body portions 65 . In this example, an example in which the tension coil spring 63 is used as the pressing force applicator is shown, but the present invention is not limited to this. and the like using a screw mechanism.

<Swing Means>
The rocking means 9 comprises a push/pull rod 71 , a crank 73 and an electric motor 75 . The electric motor 75 is fixedly installed on the saddle 77 . Here, as shown in FIG. 1A, the saddle 77 is positioned laterally (perpendicular to the X-axis) of the region where the object to be polished (the ball screw 100) is arranged between the chuck device 51 and the tailstock 53. on the positive direction side of the Y axis) so as to be movable in the positive and negative directions of the X axis.

As shown in FIG. 2 , the push/pull rod 71 is arranged between the pair of arm members 61 and the electric motor 75 . The crank 73 is arranged between the push/pull rod 71 and the electric motor 75 . One end of the push/pull rod 71 is connected to the pair of arm members 61 via a pivot shaft 70 that pivots the pair of arm main bodies 65 . The other end of the push/pull rod 71 is connected to the tip of the crank 73 via a connecting pin 81 . A base end portion of the crank 73 is fixed to an output shaft 83 of the electric motor 75 .

In the rocking means 9, the crank 73 is rotated by the operation of the electric motor 75, and the rotation of the crank 73 reciprocates the push/pull rod 71 in its longitudinal direction. As a result, where R is the distance between the center of the ball screw 100 and the center of the pivot shaft 70 and F is the push/pull force of the push/pull rod 71, a torque of F×R is applied around the axis of the ball screw 100. Then, the pair of grinding bodies 3 are swung about the axis of the ball screw 100 via the pair of arm members 61 connected to the push/pull rod 71, that is, rotated about the axis of the ball screw 100 by a predetermined angle in forward and reverse directions. It can be rotated repeatedly within a range.

A polishing operation of the ball screw 100 using the screw shaft polishing apparatus 1 configured as described above will be described.

FIG. 6 is a plan view showing the polishing operation. FIG. 6(a) is a state diagram of grinding one end of the ball screw 100, FIG. 6(b) is a state diagram of grinding the intermediate portion of the ball screw 100, and FIG. FIG. 4 is a state diagram of polishing the other end of the screw 100;

First, as shown in FIG. 6(a), one end of the ball screw 100 is gripped by the chuck device 51, and the center of the other end of the ball screw 100 is brought into contact with the center of the tailstock 53. Both ends are supported by a chuck device 51 and a tailstock 53 . Then, the saddle 77 is moved in the negative direction of the X axis so that the pair of grinding bodies 3 do not interfere with the ball screw 100, and when the pair of grinding bodies 3 are positioned near one end of the ball screw 100, the saddle 77 is moved. to stop

<Placement process>
Next, the pair of arm members 61 is operated vertically while opening the pair of arm members 61 so as to separate the pair of arm members 61 from each other against the biasing force of the tension coil spring 63 shown in FIG. The positions are adjusted so that the pair of grinding bodies 3 are located on both sides of the ball screw 100 in the direction perpendicular to the axis. Subsequently, while finely adjusting the relative position of the pair of grinding bodies 3 with respect to the ball screw 100 so that the female threaded grinding parts 10 of the pair of grinding bodies 3 engage with the male threaded part 100b of the ball screw 100, the pair of arms The pair of arm members 61 are closed so as to rely on the biasing force of the tension coil spring 63 acting to bring the members 61 closer together, and the pair of polishing bodies 3 are brought into a state capable of polishing so as to sandwich the ball screw 100 from both sides. Deploy.

The biasing force of the tension coil spring 63 is transmitted to the pair of grinding bodies 3 via the pair of arm members 61, so that the pressing force of the female threaded grinding portion 10 against the male threaded portion 100b is evenly applied from both sides in the direction perpendicular to the axis of the ball screw. can act on In this way, by the pressing force of the female threaded polishing portion 10 against the male threaded portion 100b, the portions of the plurality of polishing sheets 15 forming the female threaded polishing portion 10 are bent according to the surface shape of the male threaded portion 100b. The ridges of the internally threaded grinding portion 10 can be deeply inserted into the grooves so that they are in close contact with each other.

<Rotation process>
Following the placement step, as shown in FIGS. 6(a) to 6(c), a rotation step for rotating the ball screw 100 is performed. That is, as shown in FIGS. 6A to 6C, the ball screw 100 is rotated around the axis _S1 by operating the chuck device 51. As shown in FIGS. Assuming that the ball screw 100 is replaced with a bolt and the pair of polishing bodies 3 are replaced with a nut screwed onto the bolt, the rotation at this time is the same direction as the rotation of the nut in the direction of loosening the bolt. In this way, the ridges of the female threaded grinding portion 10 are deeply inserted into the grooves of the male threaded portion 100b, and grinding is performed in a state in which they are in close contact with each other. At this time, when the male threaded portion 100b rubs against the female threaded polishing portion 10 due to the screw feeding thrust applied from the male threaded portion 100b to the female threaded polishing portion 10 as the ball screw 100 rotates, the female threaded portions of the plurality of polishing sheets 15 are pushed together. Since the portion constituting the polishing portion 10 bends according to the surface shape of the male threaded portion 100b, polishing is performed in a state of being in close surface contact with the male threaded portion 100b. In addition, between the ball screw 100 and the pair of grinding bodies 3, the pressing force of the female thread grinding portion 10 against the male thread portion 100b is applied from both sides of the ball screw 100. Therefore, even if the pressing force is increased, The ball screw 100 does not bend, and the polishing operation is not hindered. Therefore, the external thread portion 100b of the ball screw 100 can be ground uniformly and accurately without interfering with the grinding operation.

6(a) to 6(c), in the pair of polishing bodies 3, a screw feeding thrust acts on the female threaded polishing portion 10 from the male screw portion 100b. As a result, the pair of grinding bodies 3 are sent to the other end side of the ball screw 100 together with the devices constituting the pressing means 7 and the swinging means 9 (hereinafter referred to as "attached devices"). Here, in order to smoothly feed the pair of polishing bodies 3 together with the accessory equipment to the other end side of the ball screw 100, the saddle 77 is moved at the same speed as the feeding speed of the pair of polishing bodies 3 by a feeding device (not shown) to move the saddle 77 along the X axis. move in the positive direction. In this way, the ball screw 100 is smoothly polished from the portion near one end to the other end.

<Oscillating process>
FIG. 7 is an explanatory diagram of the swinging process. During the rotation process, a rocking process for rocking the pair of polishing bodies 3 around the axis of the ball screw 100 is performed as shown in FIGS. 7(a) to 7(d). That is, the electric motor 75 is operated to rotate the crank 73, and the rotation of the crank 73 reciprocates the push/pull rod 71 in its longitudinal direction. As a result, the pair of polishing bodies 3 are swung around the axis of the ball screw 100 via the pair of arm members 61 connected to the push/pull rod 71 .

In the swinging process, the pair of arm members 61 are swung (rotated) around the ball screw 100 at a constant swing angle (rotational angle) by the push/pull rod 71 which is reciprocated by the rotation of the crank 73. Therefore, the pair of polishing bodies 3 attached to the pair of arm members 61 can be oscillated around the ball screw 100 at a constant amount of oscillation and at a constant oscillation period. In this way, by the cooperation of the pressing means 7 and the swinging means 9, the entire groove portion between the adjacent thread portions in the male thread portion 100b of the ball screw 100 can be ground more uniformly and accurately.

In the screw shaft grinding apparatus 1 of the present embodiment, by providing the oscillating means 9, the entire groove of the ball screw 100 can be ground uniformly and accurately by setting the pair of grinding bodies 3 on the ball screw 100 once. can. This will be explained below.

FIG. 8 is a diagram showing a layered state of a portion of the polishing body 3. As shown in FIG. FIG. 8(a) is a diagram showing a case where the male threaded portion 100b of the ball screw 100 relatively moves down the steps of the plurality of polishing sheets 15. FIG. FIG. 8(b) is a diagram showing a case where the male threaded portion 100b of the ball screw 100 relatively moves so as to climb the steps of the plurality of polishing sheets 15. As shown in FIG. In FIGS. 8(a) and 8(b), the thickness of each layer in the laminated structure and the form of lamination are not exact reproductions of the thickness of each layer and the form of lamination of the actual polishing body 3. It is appropriately exaggerated so that the lamination state can be easily grasped.

As shown in FIGS. 8(a) and 8(b), the polishing body 3 includes a plurality of polishing sheets 15, and the internally threaded polishing portion 10 is a predetermined portion (to which the polishing material 27 is attached) of the plurality of polishing sheets 15. parts) are overlapped to form a screw shape. In the internally threaded ground portion 10 formed in this manner, when the threaded portion of the externally threaded portion 100b of the ball screw 100 rotates relative to the ball screw 100, the threaded portions of the externally threaded portion 100b of the ball screw 100 are mutually aligned along the arrow _R1 in FIG. 8(a). The first threaded surface 10a, which is in sliding contact with the superimposed adjacent polishing sheets 15 while relatively moving down the steps, and the threaded portion of the male threaded portion 100b of the ball screw 100 are aligned as indicated by the arrow R in FIG. 8(b). ₂ , and has a second threaded surface 10b which is in sliding contact while relatively moving so as to climb the steps of the adjacent polishing sheets 15 superimposed on each other.

When the internally threaded ground portion 10 has such a first thread surface 10a and a second thread surface 10b, when the ball screw 100 is rotated by the rotating means 5, as shown in FIG. , on the first threaded surface 10a, the polishing sheet 15 (15A) on the front side beyond the step with which the threaded portion of the male screw portion 100b contacts before going over the step of the adjacent polishing sheets 15 superimposed on each other is The pressing force that presses the polishing sheet 15 (15B) behind the step with which the thread portion of the male thread portion 100b comes into contact after crossing over the step overlaps with each other as the thread portion moves relative to the first thread surface 10a. The threaded portion of the male screw portion 100b is ground while the abrasive sheets 15 are in close contact with each other. On the other hand, as shown in FIG. 8(b), on the second thread surface 10b, between the polishing sheet 15 (15A) on the front side over the step and the polishing sheet 15 (15B) on the rear side over the step. The threaded portion of the male threaded portion 100b is moved relative to the second threaded surface 10b in such a direction that the threaded portion of the male threaded portion 100b bites in, and the abrasive sheet 15 (15A) on the front side beyond the step is moved. The male thread portion is in such a state that a pressing force is applied to the polishing sheet 15 (15A) on the front side of the step so that the polishing sheets 15 (15A, 15B) are separated from the polishing sheet 15 (15B) on the rear side of the step. A grinding operation will be performed to grind the threads of 100b.

For this reason, in the male thread portion 100b of the ball screw 100, the portion on one side in the axial direction and the portion on the other side of the thread portion, for example, the portion on the one side in the axial direction contacts the first thread surface 10a, When the portion on the other side in the direction comes into contact with the second thread surface 10b, the portion on the one side in the axial direction is ground well, while the portion on the other side in the axial direction is ground on the first thread surface. It will not perform as well as polishing with 10a. As a result, a difference in grinding accuracy occurs between the portion on one side and the other side in the axial direction of the thread portion of the male thread portion 100b of the ball screw 100 . In other words, there is a difference in polishing accuracy between a portion on one side in the axial direction and a portion on the other side of the groove formed between adjacent thread portions in the male screw portion 100b of the ball screw 100 . In view of such a difference in polishing accuracy, in order to polish the entire groove uniformly and accurately, a portion functioning as the first thread surface 10a and a portion functioning as the second thread surface 10b are required. It is conceivable to change the setting of the pair of polishing bodies 3 with respect to the ball screw 100 so as to exchange the directions of the two, and perform the polishing operation again. However, in this case, it is expected that the setting change will take time and effort, and the time required for the polishing will become longer because the polishing will be performed again.

Therefore, in the screw shaft grinding apparatus 1 of the present embodiment, the pair of grinding bodies 3 are rocked around the ball screw 100 by the rocking means 9, so that the first thread surface 10a of the pair of grinding bodies 3 is and the portion functioning as the second thread surface 10b are switched according to the oscillation period of the pair of polishing bodies 3. As shown in FIG. As a result, it is equivalent to contacting the first thread surface 10a capable of good grinding to the entire groove portion of the male thread portion 100b of the ball screw 100. As shown in FIG. Therefore, after changing the setting of the pair of grinding bodies 3 with respect to the ball screw 100, the direction of the portion functioning as the first thread surface 10a and the direction of the portion functioning as the second thread surface 10b are exchanged. To polish the entire groove uniformly and accurately without performing polishing operation again, save labor for setting change, shorten the time required for polishing, and improve polishing efficiency. can be done.

As described above, the screw shaft polishing apparatus and the screw shaft polishing method of the present invention have been described based on one embodiment, but the present invention is not limited to the configuration described in the above embodiment, and does not deviate from the gist thereof. The configuration can be appropriately changed within the range.

INDUSTRIAL APPLICABILITY The screw shaft polishing apparatus and the screw shaft polishing method of the present invention can be used, for example, for polishing screw shafts such as ball screws, screw gauges and taps, and for polishing the external thread portion of the screw shaft.

REFERENCE SIGNS LIST 1 screw shaft polishing device 3 polishing body 5 rotating means 7 pressing means 9 rocking means 10 female threaded polishing portion 15 polishing sheet 61 arm member 71 push/pull rod 73 crank 100 ball screw (screw shaft)
100b male screw

Claims (5)

A screw shaft polishing device for polishing a male thread portion of a screw shaft,
a pair of polishing bodies having a flexible female-threaded polishing portion that engages with the male-threaded portion and arranged to sandwich the screw shaft from both sides;
pressing means for pressing the polishing body against the screw shaft;
a rotating means for rotating the screw shaft;
A screw shaft polishing device comprising: The polishing body includes a plurality of polishing sheets arranged in a laminated state in the axial direction of the screw shaft,
The internally threaded polishing portion is formed by superimposing the polishing sheets so as to form a screw shape,
2. The screw shaft polishing apparatus according to claim 1, further comprising swinging means for swinging said polishing body around said screw shaft. The pressing means includes a pair of arm members having one end attached with the polishing body and the other end side being pivotally connected to each other. pressing against the screw shaft;
The rocking means is
a push/pull rod having one end connected to the arm member;
a crank connected to the other end of the push/pull rod;
including
3. A threaded shaft grinding apparatus according to claim 2, wherein said grinding body is oscillated around said threaded shaft via said arm member by reciprocating said push/pull rod by rotation of said crank. A screw shaft polishing method for polishing a male threaded portion of a screw shaft, comprising:
an arranging step of arranging a pair of polishing bodies having a flexible female-threaded polishing portion that engages with the male-threaded portion so as to sandwich the screw shaft from both sides;
a pressing step of pressing the polishing body against the screw shaft;
a rotating step of rotating the screw shaft;
A screw shaft polishing method comprising: The polishing body includes a plurality of polishing sheets arranged in a laminated state in the axial direction of the screw shaft,
The internally threaded polishing portion is formed by superimposing the polishing sheets so as to form a screw shape,
5. A screw shaft grinding method according to claim 4, wherein said grinding body is swung around said screw shaft during said rotating step.

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