JP2008296304A - Ball screw, ball screw assembling device, and method of assembling ball screw using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball screw assembling device enhancing the durability of a ball screw by filling a nut with a sufficient quantity of balls, and also to provide a method of assembling the ball screw using the assembling device. <P>SOLUTION: The offset amount L between the center axis of a ball pusher 45 and the inscribed circle of the balls 4 put in the screw groove 3a of the nut 3 is, where the diameter of the balls is Dw, the requirement of Dw/2 < L < Dw is desirable. More desirably, the offset amount L is set as close to Dw/2 as possible. When the offset amount L is larger than Dw, the balls may remain between the end of the ball pusher 45 and the track of the screw groove 3a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ball screw having a screw shaft, a nut and a ball, a ball screw assembling apparatus, and a ball screw assembling method using the same.

  In electric actuators used in various drive units of vehicles such as automobiles, a gear mechanism such as a trapezoidal screw or a rack and pinion is generally used as a mechanism for converting the rotational movement of the electric motor into a linear linear movement. Yes. Since these conversion mechanisms involve a sliding contact portion, the power loss is large, and it is necessary to increase the size of the electric motor and increase the power consumption. Therefore, a ball screw mechanism has been adopted as a more efficient actuator.

  This ball screw is composed of a screw shaft in which a spiral ball rolling groove is formed on the outer periphery, a nut in which a spiral ball rolling groove is formed in a cylindrical surface, and both opposing ball rolling grooves. It is a mechanical element that is composed of a large number of balls that are rotatably accommodated in the ball rolling path, and converts the rotation of the screw shaft or nut into translational motion in the axial direction.

As a method for assembling the ball screw, for example, there is a method as disclosed in Patent Document 1. In this example, the top member is fixed to the nut in advance or integrally formed, a ball insertion jig is inserted into the nut, and a predetermined number of balls are supplied from the ball insertion jig toward the thread groove on the inner surface of the nut. Yes. This ball insertion jig is provided with the same number of ball supply holes as the number of circulation rows, and the outlet of this ball supply hole is installed at the highest position of the nut raceway groove forming the corresponding circulation row, A predetermined ball is aligned and continuously supplied to each ball supply hole, and a ball that has not been able to enter the circulation train track by its own weight is pushed by an insertion rod to fill the nut with the ball.
JP-A-5-138458

  However, in the conventional ball screw assembling method, the ball remaining in the ball supply hole is pushed into the thread groove with the insertion rod, but there is a gap between the tip of the insertion rod and the thread groove. There is a possibility that the balls remain and the screw grooves are not filled with a sufficient number of balls, and in this case, the durability of the ball screw is lowered.

  The present invention has been made in view of such circumstances, and a ball screw, a ball screw assembling apparatus, and a ball screw using the ball screw that can fill a nut with a sufficient number of balls to improve the durability of the ball screw. It is an object to provide an assembly method.

  In order to achieve such an object, the present invention provides a screw shaft having a helical thread groove formed on the outer peripheral surface, a nut externally fitted to the screw shaft, and a spiral screw groove formed on the inner peripheral surface. An assembly device for a ball screw comprising a large number of balls accommodated in a rolling path formed by corresponding screw grooves, and having a ball supply hole for supplying the balls to the screw grooves of the nut, A ball guide that is inserted into the nut; a ball pusher that is inserted into the ball supply hole and pushes the ball in the ball supply hole into a screw groove of the nut; and a central axis of the ball pusher and the ball pusher The offset amount L of the inscribed circle of the ball in a state where the ball is filled in the thread groove of the nut is set such that Dw / 2 <L <Dw, where Dw is the ball diameter.

  Thereby, since the ball does not remain between the ball supply hole and the thread groove of the nut, the nut can be filled with a sufficient number of balls, and the durability of the ball screw can be improved.

  In addition, the present invention further includes a locating jig that is arranged to be slidable in the horizontal direction with respect to the ball guide and has a ball hole for holding a predetermined number of the balls. Can be held by a fixed jig, and the quantity of balls filled in the nut can be strictly controlled.

  Further, according to the present invention, since the ball hole of the fixed jig is set to a length obtained by multiplying the number of balls incorporated in each circulation row of the nut by the ball diameter, a predetermined number of balls can be easily and accurately applied. Can be supplied to the ball supply hole.

  In addition, the present invention further includes an insertion shaft having a cylindrical portion that is fitted to the nut and is fitted to a stepped portion at the tip of the ball guide and a small diameter portion at the tip of the screw shaft. The guide and screw shaft can be more securely inserted and the ball screw can be assembled more smoothly.

  The present invention is also a ball screw assembling method using the ball screw assembling apparatus, the step of supplying the ball to the thread groove of the nut through the ball supply hole of the ball guide, and the ball Since the step of pushing the ball in the supply hole with a ball pusher is provided, a sufficient number of balls can be filled in the nut, and the durability of the ball screw can be improved.

  The present invention also provides a screw shaft that is assembled by the above-described ball screw assembly method and that has a helical thread groove formed on the outer peripheral surface thereof, and is externally fitted to the screw shaft and has a helical thread groove formed on the inner peripheral surface thereof. And a large number of balls accommodated in the rolling path formed by the corresponding screw grooves, so that the nut can be filled with a sufficient number of balls and the durability of the ball screw can be improved. .

  A ball screw assembling apparatus according to the present invention includes a screw shaft having a helical thread groove formed on an outer peripheral surface, and a nut externally fitted to the screw shaft and having a helical screw groove formed on an inner peripheral surface thereof. An assembly device for a ball screw comprising a large number of balls accommodated in a rolling path formed by corresponding screw grooves, and having a ball supply hole for supplying the balls to the screw grooves of the nut, A ball guide that is inserted into the nut; a ball pusher that is inserted into the ball supply hole and pushes the ball in the ball supply hole into a screw groove of the nut; and a central axis of the ball pusher and the ball pusher The offset amount L of the inscribed circle of the ball in a state where the ball is filled in the thread groove of the nut is set to Dw / 2 <L <Dw where Dw is the ball diameter. Filling the balls It is possible to improve the durability of the ball screw.

  A screw shaft having a spiral thread groove formed on the outer peripheral surface, a nut externally fitted to the screw shaft and having a spiral thread groove formed on the inner peripheral surface, and a roller formed by the corresponding both screw grooves. A ball screw assembling apparatus having a large number of balls accommodated in a moving path, having a ball supply hole for supplying the ball to the screw groove of the nut, and a ball guide inserted into the nut; A ball pusher that is inserted into the ball supply hole and pushes the ball in the ball supply hole into the screw groove of the nut, and the ball is filled in the central axis of the ball pusher and the screw groove of the nut The offset amount L of the inscribed circle of the ball is set to Dw / 2 <L <Dw where the ball diameter is Dw.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a view showing an embodiment of a ball screw according to the present invention, in which (a) is a plan view, (b) is a side view, and (c) is a longitudinal sectional view.

  The ball screw 1 includes a screw shaft 2 having a helical screw groove 2a formed on the outer peripheral surface, and a nut 3 fitted on the screw shaft 2 and having a helical screw groove 3a formed on the inner peripheral surface. A large number of balls 4 accommodated in a rolling path formed by the opposing screw grooves 2a and 3a, and two or more piece members 5 serving as circulation members for the balls 4 are provided. In addition, although the two piece members 5 are shown in the figure, they can be arranged at a plurality of locations of the nut 3. Further, in this example, an example in which the screw groove 3a is formed also in the central portion of the nut 3 is shown, but the present invention is not limited to this, and the nut in which the screw groove is not formed in the central portion. It can also be applied to.

  The cross-sectional shape of each screw groove 2a, 3a of the screw shaft 2 and the nut 3 may be a circular arc shape or a gothic arc shape, but here the contact angle with the ball 4 can be taken large and the axial clearance is It is formed in a gothic arc shape that can be set small. Thereby, the rigidity with respect to an axial load becomes high and generation | occurrence | production of a vibration can be suppressed.

  Two cylindrical windows 6 having a substantially circular cross section are formed in the body of the cylindrical nut 3 so as to penetrate the inner and outer peripheral surfaces and cut out a part of the thread groove 3a. Each piece window 6 is fitted with a piece member 5 serving as a circulation member for the ball 4. Note that the piece window does not necessarily have a circular shape, and may be, for example, an oval shape. The ball circulation method is not limited to the piece type, but may be a return tube type, an end cap type, or a guide plate type.

  A connecting groove 5a that connects adjacent one rounds of the screw groove 3a is formed inward of the piece member 5. Thereby, the ball | bowl 4 can go around by the connection groove | channel 5a and the part of the substantially 1 round of the thread groove 3a. That is, the rolling path formed by the opposing screw grooves 2a and 3a becomes a circulation path (circulation line). A large number of balls 4 interposed between the inner and outer screw grooves 2a and 3a in the rolling path roll along the screw grooves 2a and 3a, and are guided by the connecting groove 5a of the piece member 5 to be screw shafts. 2 over the thread 2 and return to the adjacent thread groove 3a, and roll along the thread grooves 2a and 3a again.

  The connecting groove 5a of the piece member 5 is formed to be curved in an S shape so as to smoothly connect the adjacent screw grooves 3a and 3a of the nut 3, and is smoothly connected to the screw groove 3a. The depth of the connecting groove 5a is set to a depth at which the ball 4 can exceed the thread of the screw groove 2a in the screw shaft 2 within the connecting groove 5a.

  A notch 3 b is formed at the outer diameter end of the nut 3. The notch 3 b is a flattened outer diameter end of the nut 3, and is formed only at one end of the nut 3. By forming the cutout portion 3b, the side surface of the nut 3 becomes a D-shaped convex portion 3c protruding in a substantially D shape as a result. The D-shaped convex portion 3c is fitted into the substantially D-shaped concave portion 27c (see FIG. 3) of the nut base 27, and the screw groove 3a of the nut 3 and the opening 41d of the ball supply hole of the ball guide. (See FIG. 2). The notch 3b is preferably provided only on one end face side of the nut 3 in the cylindrical axis direction. For example, if the notch is formed over the entire axial direction of the nut, the cross-sectional shape of the nut is substantially D-shaped no matter where it is taken, but both end surfaces of the nut are also D-shaped. When fitted into the substantially D-shaped concave portion, there is a possibility that the upper and lower sides are attached upside down. In this case, the screw groove of the nut and the opening of the ball supply hole of the ball guide cannot be accurately aligned, and the ball cannot be normally assembled. Further, since the notch 3b is provided, when the nut 3 is fitted upside down on the nut pedestal, the nut 3 is lifted, so that the end face height of the nut is detected by an inexpensive target sensor or the like. As a result, it is possible to detect the reverse set of nuts and to prevent assembly problems.

  The piece member 5 is made of a sintered alloy formed by an injection molding machine by adjusting the metal powder into a plastic shape. In this injection molding, first, metal powder and a binder made of plastic and wax are kneaded by a kneader, and the kneaded product is granulated into pellets. The granulated pellets are molded by so-called MIM (Metal Injection Molding), which is supplied to a hopper of an injection molding machine and pushed into a mold in a heated and melted state. A sintered alloy formed by such an MIM can be easily and accurately formed into a desired shape / dimension even if it has a high workability and a complicated shape.

Next, an embodiment of a ball screw assembling apparatus according to the present invention will be described.
FIG. 2 is a front view showing an embodiment of a ball screw assembling apparatus according to the present invention. FIG. 3 is a plan view of the nut base. FIG. 4 is a plan view of the nut fixing portion.

  As shown in FIG. 2, the ball screw assembly device 10 according to the present invention includes a nut fixing portion 11 on which a nut 3 is placed, an insertion shaft 12 to be inserted into a through hole of the nut fixing portion 11, and a vertical direction. And a ball supply unit 13 for supplying a ball to the nut 3.

  A base 21 having a hole at the center is disposed below the nut fixing portion 11. On the upper part of the base 21, a base 22 having a hole in the center is placed. At the upper part of the base 22, there is provided an outer cylinder 23 having a circular shape at the center and a flange having a flange for fixing to the base 22 at the lower end as a whole. Roller bearings 24 and 25 are arranged at two locations on the inner peripheral surface of the outer cylinder 23, upper and lower. An inner cylinder 26 having a cylindrical shape as a whole is disposed on the inner circumference of the rolling bearings 24 and 25. The inner cylinder 26 is rotatable with respect to the outer cylinder 23. A nut base 27 on which the nut 3 is placed is fixed to the upper portion of the inner cylinder 26.

  As shown in FIG. 3, a circular hole 27 a is formed in the center of the nut base 27. A hole 27 b having a predetermined depth for fitting the nut 3 is formed on the upper surface of the nut base 27. A substantially D-shaped concave portion 27c is further formed on the lower surface of the hole 27b. A portion of the lower surface of the hole 27b where the D-shaped concave portion 27c is not formed is a convex portion 27d that is one step higher. When the nut 3 is fitted into the circular hole 27a, the D-shaped convex portion 3c of the nut 3 is fitted into the D-shaped concave portion 27c, and the notched portion 3b of the nut 3 is fitted into the convex portion 27d. Therefore, the nut 3 can be prevented from being installed upside down, and the nut 3 can be aligned around the axis, so that the screw groove of the nut 3 and the tip of the ball supply hole of the ball guide are accurately aligned. The ball can be accurately supplied to the nut 3.

  A motor mounting table 32 having an L-shaped cross section for mounting the motor 31 is fixed to the side surface of the base 22 with bolts. A rotating member 33 having a flange at the upper end is fitted to the rotating shaft of the motor 31. The flange portion of the rotating member 33 is provided with a through hole penetrating in the vertical direction. A first coupling 34 is rotatably provided in the through hole of the rotating member 33. A hole penetrating in the horizontal direction is provided at the center of the first coupling 34, and one end of a rod-like arm 35 is inserted. The other end of the arm 35 is rotatably fitted in a hole of a second coupling 36 having the same shape as the first coupling 34. A connecting member 37 having an L-shaped cross section is rotatably connected to the lower end of the second coupling 36. The other end of the connecting member 37 is fixed to the outer peripheral surface of the inner cylinder 26 with a bolt. The rotation member 33, the first coupling 34, the arm 35, the second coupling 36 and the connecting member 37 constitute a link mechanism 38.

  With this configuration, as shown in FIG. 4, the motor 31 and the nut base 27 are connected by the link mechanism 38. Therefore, when the rotation shaft of the motor 31 is continuously rotated, the rotating member 33 is rotated and the first cup is rotated. The ring 34 rotates around the rotation axis of the motor 31. Then, when the connecting member 37 repeats horizontal movement around the central axis of the nut pedestal 27, the nut pedestal 27 swings around its axis. As a result, an unfilled space for the ball is repeatedly generated in the thread groove track of the nut each time the rocking motion is performed, and the ball can easily enter the unfilled space, and the ball can be filled in a short time. Further, since the vibration is generated in the nut 3 by the swinging motion, the ball can easily flow along the screw groove, and the filling of the ball into the nut screw groove is promoted without difficulty.

  The insertion shaft 12 is inserted into a through hole provided at the center of the inner cylinder 26 and the nut base 27. The upper portion of the insertion shaft 12 is a stepped portion having a reduced diameter, and further ahead is a cylindrical portion 12a having the same outer diameter as the stepped portion. The cylindrical portion 12a is inserted into the nut 3 with a clearance. The outer diameter of the cylindrical portion 12 a is slightly smaller than the inscribed circle of the ball 4 when the ball 4 is filled in the nut 3.

  A shaft-shaped ball guide 41 that is inserted into the nut 3 is provided at the lower end of the ball supply unit 13. At a position eccentric from the axial center inside the ball guide 41, at least one ball supply hole 41a extending in the vertical direction is formed. The lower end of the ball supply hole 41a is an opening 41d that opens toward the side surface of the ball guide 41, so that the ball 4 can be supplied from the ball supply hole 41a to the thread groove 3a of the nut 3. A stepped portion 41 b with a reduced diameter is formed at the lower end of the ball guide 41 and is fitted into the cylindrical portion 12 a of the insertion shaft 12.

  A counting sensor 42 that counts the number of passing balls 4 supplied to the nut 3 is disposed on the side surface above the ball guide 41. A through hole 41c is provided in the horizontal direction from the tip of the counting sensor 42 to the side surface of the ball supply hole 41a. The counting sensor 42 counts the number of passing balls 4 through the through hole 41c. As the counting sensor 42, for example, a transmissive or diffuse reflection photoelectric sensor can be exemplified. In the case of the transmissive type, it is necessary to provide a light receiving portion on the side of the ball supply hole 41a.

  A ball supply member 43 is fixed to the upper portion of the ball guide 41 with bolts. The ball supply member 43 has a substantially U-shaped cross section, and a rectangular parallelepiped-shaped fixing jig 44 is disposed in the U-shaped recess. The fixed jig 44 is slidable in the horizontal direction with respect to the ball supply member 43. Ball holes 43a, 43b, and 44a communicating with the ball supply holes 41a are formed in the ball supply member 43 and the fixed distribution jig 44 so as to penetrate in the vertical direction. In the upper part of the ball supply member 43, a ball supply path 43c through which a ball is supplied from the outside is formed so as to penetrate the ball hole 43b in a vertical direction. Further, since the ball holes 44a of the fixed jig 44 are set to a length obtained by multiplying the number of balls incorporated in each circulation row of the nut 3 by the ball diameter, a predetermined number of balls are held in the ball holes 44a. In this state, the fixed distribution jig 44 is slid, the ball hole 44a and the ball supply hole 41a are communicated, and the ball is supplied from the ball supply hole 41a to the thread groove 3a of the nut 3, whereby one circulation row of the nut 3 is provided. It is possible to supply an accurate number of balls.

  In FIG. 2, a rod-shaped ball pusher 45 is inserted into the ball supply hole 41a and the ball holes 43a, 43b, and 44a. The tip of the ball pusher 45 is rounded into a hemisphere, and is used for the purpose of pushing the ball 4 into the nut 3. A holding member 45 a that holds the ball pusher 45 is disposed at the upper end of the ball pusher 45.

Next, the ball screw assembling method according to the present invention will be described.
FIG. 5 is a front view of the apparatus showing the process of lowering the ball guide. FIG. 6 is a front view of the apparatus showing a process of sliding the fixed jig. FIG. 7 is a front view of the apparatus showing the process of lowering the ball pusher. FIG. 8 is an enlarged view of a main part of FIG. FIG. 9 is a front view of the apparatus showing the process of loading the screw shaft. FIG. 10 is a front view of the apparatus when the assembly of the ball screw is completed.

  In the ball screw assembling method of the present invention, first, the nut 3 is placed on the nut base 27 in the vertical direction as shown in FIG. At this time, the nut 3 can be aligned at the same time by fitting the D-shaped convex portion 3 c of the nut 3 to the D-shaped concave portion 27 c of the nut base 27. Further, the insertion shaft 12 is inserted into the nut pedestal 27 and the like, and the cylindrical portion 12 a of the insertion shaft 12 is inserted into the inner peripheral surface of the nut 3.

  Next, as shown in FIG. 5, the ball supply unit 13 is lowered. At this time, the stepped portion 41 b at the tip of the ball guide 41 is fitted into the cylindrical portion 12 a of the insertion shaft 12, and the insertion shaft 12 is also lowered as the ball guide 41 is lowered. Then, the ball guide 41 is fitted into the nut 3. The position of the opening 41 d of the ball guide 41 is controlled so as to face the screw groove 3 a of the lowermost circulation row among the screw grooves 3 a of the nut 3. Further, the distribution jig 44 slides in the horizontal direction (rightward in FIG. 5) with respect to the ball supply member 43, the ball hole 44a and the ball supply path 43c are communicated, and a predetermined number of balls are placed in the ball hole 44a. Retained. Further, as the ball supply unit 13 is lowered, the ball pusher 45 is relatively positioned above the ball supply unit 13. Thus, by disposing the ball pusher 45 upward, the screw groove 3a of the nut 3 and the ball supply hole 41a and the ball holes 43a, 43b, 44a can be communicated, and the ball is inserted into the screw groove 3a of the nut 3. Can be supplied.

  Next, as shown in FIG. 6, the fixed jig 44 is slid in the horizontal direction (leftward in FIG. 5) with respect to the ball supply member 43, whereby the screw groove 3a of the nut 3 and the ball supply hole 41a, The ball holes 43 a and 44 a can be communicated, and a predetermined number of balls held in the ball hole 44 a can be supplied to the thread groove 3 a of the nut 3. At this time, by counting the number of balls supplied from the ball hole 44a to the screw groove 3a by the counting sensor 42, the number of balls supplied to the nut 3 can be grasped more accurately. Further, when the ball is supplied to the screw groove 3a, the motor 31 is driven and the nut pedestal 27 is caused to swing, whereby the ball can be smoothly filled into the screw groove 3a.

  Next, as shown in FIG. 7, with the thread groove 3a of the nut 3 and the ball supply hole 41a and the ball holes 43a, 43b, and 44a in communication, the ball pusher 45 is lowered, and the ball in the ball supply hole 41a is removed. Push into the thread groove 3a. The position of the ball pusher 45 is accurately controlled, and the tip of the ball pusher 45 is pushed to the vicinity of the opening 41d of the ball guide 41, so that the ball does not remain in the ball supply hole 41a and the ball supply hole 41a. All the balls supplied inside are filled in the thread groove 3 a of the nut 3.

  Here, as shown in FIG. 8, the offset amount L of the inscribed circle of the ball 4 in a state where the ball 4 is filled in the central axis of the ball pusher 45 and the thread groove 3a of the nut 3 is expressed as follows. It is preferable that Dw / 2 <L <Dw. More preferably, the offset amount L is as close to Dw / 2 as possible. Here, since the outer diameter of the ball guide 41 is substantially equal to the inscribed circle diameter of the ball 4 in a state where the thread groove 3a of the nut 3 is filled with the ball 4, this offset amount L is smaller than Dw / 2. Then, the ball 4 in the ball supply hole 41a breaks through the outer peripheral surface of the ball guide 41, and the durability of the ball guide 41 cannot be ensured. On the other hand, if the offset amount L is larger than Dw, the ball may remain between the tip of the ball pusher 45 and the track of the screw groove 3a.

  Since the balls 4 are filled in one circulation row of the nut 3 by the above steps, these steps are performed for each circulation row of the nut 3. Specifically, when the filling of one circulation row is completed, the insertion shaft 12 and the ball guide 41 are raised by one circulation row, and the fixed jig 44 is slid to a predetermined number of balls in the ball hole 44a. Then, the distribution jig 44 is slid again so that the thread groove 3a of the nut 3 communicates with the ball supply hole 41a and the ball holes 43a and 44a. Then, the ball pusher 45 is lowered to push the ball 4 into the screw groove 3a. By repeating these steps, the balls are filled in all the circulation rows of the nut 3.

  Next, as shown in FIG. 9, the insertion shaft 12 is raised, a stepped portion 41 b at the tip of the ball guide 41 is fitted into the cylindrical portion 12 a of the insertion shaft 12, and the ball supply unit is connected together with the ball guide 41. Push 13 up. If it does so, it will be in the state by which the cylindrical part 12a of the insertion shaft 12 was fitted inside the ball | bowl 4 with which the nut 3 was filled. From this state, the screw shaft 2 is loaded onto the insertion shaft 12 such that the small diameter portion 2b at the tip of the screw shaft 2 of the ball screw 1 is fitted into the cylindrical portion 12a of the insertion shaft 12.

  Next, as shown in FIG. 10, by rotating the nut 3 or the screw shaft 2 around the axis, the screw groove 3 a of the nut 3 is inserted into the screw groove 2 a of the screw shaft 2 via the ball 4 filled in the nut 3. To complete the assembly of the ball screw 1.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  A ball screw, a ball screw assembling apparatus and a ball screw assembling method using the same according to the present invention include a ball screw having a screw shaft, a nut and a ball, a ball screw assembling apparatus, and a ball screw assembling method using the same. Applicable to.

It is a figure which shows embodiment of the ball screw which concerns on this invention, (a) is a top view, (b) is a side view, (c) is a longitudinal cross-sectional view. It is a front view which shows embodiment of the assembly apparatus of the ball screw which concerns on this invention. It is a top view of a nut base. It is a top view of a nut fixing | fixed part. It is a front view of the device showing the process of lowering the ball guide. It is a front view of the apparatus which shows the process of sliding the fixed distribution jig. It is a front view of the device showing the process of lowering the ball pusher. It is a principal part enlarged view of FIG. It is a front view of the apparatus which shows the process which loaded the screw shaft. It is a front view of an apparatus when the assembly of a ball screw is completed.

Explanation of symbols

1 ······ Ball screw 2 ··· Screw shaft 2a, 3a ··· Screw groove 2b ··· Small diameter portion 3 ··· Nut 3b ··· Notch 3c ... D-shaped convex part 4 ... Ball 5 ... Piece member 5a ... Connection groove 6 ... Piece window 10 ... Ball screw assembly device 11 Nut fixing portion 12 Insertion shaft 12a Cylindrical portion 13 Ball supply portion 21 Base 22 .... Base 23 ... Outer cylinders 24, 25 ... Rolling bearing 26 ... Inner cylinder 27 ... Nut base 27a ... Round hole 27b ... Hole 27c ··· D-shaped concave portion 27d ··· convex portion 31 ··· motor 32 ··· motor mounting base 33 ··· rotating member 34 ··· first cup Ring 35 ... · Arm 36 ··· Second coupling 37 ··· Connection member 38 ··· Link mechanism 41 ··· Ball guide 41a ··· Ball supply hole 41b ··· Stepped portion 41c ... through hole 41d ... opening 42 ... counting sensor 43 ... ball supply members 43a, 43b, 44a ... ball hole 43c ...・ Ball supply passage 44... Fixed distribution jig 45... Ball pusher 45 a... Holding member L... Offset amount Dw.

Claims (6)

A screw shaft having a spiral thread groove formed on the outer peripheral surface, a nut externally fitted to the screw shaft and having a spiral thread groove formed on the inner peripheral surface, and a roller formed by the corresponding both screw grooves. A ball screw assembling apparatus having a large number of balls accommodated in a moving path,
A ball supply hole that supplies the ball to the thread groove of the nut; a ball guide that is inserted into the nut; and a ball guide that is inserted into the ball supply hole, and the ball in the ball supply hole is inserted into the nut The ball pusher is pushed into the thread groove, and the offset amount L of the inscribed circle of the ball in a state where the ball is filled in the center axis of the ball pusher and the thread groove of the nut is expressed as Dw / 2 <L <Dw. A ball screw assembling apparatus.   The ball screw assembling apparatus according to claim 1, further comprising a locating jig that is arranged to be slidable in a horizontal direction with respect to the ball guide and in which a ball hole for holding a predetermined number of balls is formed.   The ball screw assembly apparatus according to claim 2, wherein the ball hole of the fixed jig is set to a length obtained by multiplying the number of balls incorporated in each circulation row of the nut by the ball diameter.   4. The insertion shaft according to claim 1, further comprising an insertion shaft that is inserted into the nut and has a cylindrical portion that is fitted into a stepped portion at the tip of the ball guide and a small diameter portion at the tip of the screw shaft. The ball screw assembling apparatus described in 1. A ball screw assembling method using the ball screw assembling apparatus according to any one of claims 1 to 4,
Assembling the ball screw, comprising: supplying the ball to the screw groove of the nut through the ball supply hole of the ball guide; and pushing the ball in the ball supply hole with a ball pusher. A method of assembling a ball screw using the apparatus.   6. A screw shaft that is assembled by the ball screw assembling method according to claim 5 and that has a helical thread groove formed on the outer peripheral surface thereof, and is externally fitted to the screw shaft to form a helical thread groove on the inner peripheral surface. And a ball screw having a large number of balls accommodated in a rolling path formed by the corresponding screw grooves.

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