JP6180912B2 - Linear actuator ball spline device - Google Patents

Description

  The present invention relates to a linear actuator unit, and more particularly to a linear actuator / ball spline device.

  The present invention is a transmission unit that performs relative linear motion by combining a spline shaft and a nut member via a large number of balls, and is a ball spline such as a linear guide part of a machine tool or various industrial machines or a torque transmission part of an industrial robot. Used for equipment.

  As is known, this type of ball spline device is known from the patent documents 1 and 2. The ball spline device is assembled to the spline shaft through a plurality of balls and a spline shaft having a plurality of ball transfer grooves extending along the longitudinal direction, and a nut member having an infinite circulation path for the balls; The nut member can be freely moved along the longitudinal direction around the spline shaft with the infinite circulation of the balls.

  The infinite circulation path of the ball provided in the nut member is a load passage composed of the ball rolling groove of the nut member installed on the ball and the ball rolling groove of the spline shaft, and is parallel to the load passage. And a U-shaped direction change path connecting the load path and the ball return path. And the infinite circulation path of a ball | bowl is formed by arrange | positioning the said direction change path in the both ends of a load channel | path and a ball | bowl return channel | path.

  In the ball spline device of the above-mentioned document, a synthetic resin cage is attached to a gap between an inner peripheral surface of a nut member formed in a cylindrical shape and a spline shaft passing through the inner peripheral surface. The ball return path and the direction change path are formed using the cooperation.

  Further, in order to move the ball in the load passage to the ball return passage through the direction change, it is necessary to remove the ball from the ball transfer groove of the spline shaft. For this reason, in the conventional ball spline device, the cage is provided with a ball scooping portion that is continuous with the direction change path, and the ball transferred through the ball transfer groove exceeds the scooping portion and this ball It separates from the transfer groove and is accommodated in a direction change path formed by the cooperation of the cage and the nut member.

  However, in the conventional ball spline device described above, since the ball return passage is formed by the cage and the nut member, the ball return passage projects at least in the radial direction from the spline shaft by the thickness of the cage. . Further, the direction change path or the ball return path is formed in the cage, and in order to realize this complicated shape, the cage is manufactured by injection molding of a synthetic resin. For this reason, the conventional ball spline device has the following problems.

  When the cage mounted on the inner peripheral surface of the nut member is deformed, the cage comes into contact with the spline shaft and the movement of the nut member is obstructed, so it is difficult to form the cage extremely thin. . For this reason, in the conventional ball spline device in which the cage is accommodated between the spline shaft and the nut member, the outer diameter of the nut member is affected by the thickness of the cage, and the outer diameter of the nut member is increased. It is the result.

  In the conventional ball spline device, the balls are circulated infinitely by using the cage. However, since the cage is manufactured by plastic injection molding, all the length dimensions thereof are fixed. Therefore, it cannot be applied to nuts of different lengths and is not versatile.

Japanese Utility Model Publication No. 61-179414 JP-A-58-137616

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to be able to miniaturize the outer diameter of the nut member to the limit while sufficiently exhibiting the original function, and further assembled. An object of the present invention is to provide a reliable ball spline device that does not require man-hours, can be manufactured inexpensively and easily, and can maintain quality.

  In order to solve the above problems, a kind of linear actuator / ball spline device of the present invention includes the following.

  Spline shaft. It has an elongated structure extending in one direction, this extending direction is defined as the axial direction, and the surface of this spline shaft is transferred to the ball of a device extended along multiple axial directions. There is a groove.

  Moving body. It includes a main body, two rotors, and a plurality of rolling elements. This main body has a through hole set in the spline shaft, and a ball transfer tank facing the ball transfer groove on the inner edge surface of the through hole. There is. The ball transfer groove and the ball transfer tank constitute a load passage, and an installation hole is provided at each end of the through hole. The diameter of the installation hole is larger than the diameter of the through hole, and both of them communicate with each other. Yes. The main body has an opposing ball transfer tank and a circulation hole provided in parallel to the ball transfer tank. Both ends of the circulation hole are connected to the mounting hole, and the cross section of the circulation hole is circular. The two rotors are accommodated in two mounting holes, respectively, and the rotor has a circulation path for a ball transfer tank facing each other. The outline of this circulation path is U-shaped, and at both ends thereof, a circulation path is constituted by connecting with a load path and a circulation hole. The plurality of ball transfer bodies are installed in the circulation passage.

  Due to the above structure, no retainer is installed between the spline shaft and the main body, so that the outer diameter of the main body can be reduced. The rotor is installed in the mounting holes at both ends of the main body, and the rotor can still be used in the main body even when the axial length of the main body changes. For this reason, the versatility of the rotor is enhanced.

  Further, when the ball transfer body is moved in the circulation path, better smoothness can be obtained. According to the present invention, a special passage can be designed for the circulation path in which the movement of the ball transfer body becomes the easiest and smooth, and the description thereof is as follows.

  The circulation channel is divided into four parts, and the four parts are connected in order to form a rising part, a first rotating part, a second rotating part, and a connecting part. The width of this circulation path is larger than the diameter of the ball transfer body. A part of the ascending part is accommodated in the ball transfer groove, and the ascending part has a certain ascending height and ascending length. The rising height is smaller than the rising length, and this rising length satisfies the following relational expression. 0.25 times the diameter of the ball transfer body ≤ rising length ≤ 0.5 times the diameter of the ball transfer body. The first rotating part and the second rotating part constitute one rotating part. The radius of the inner contour of the rotating part matches the following relational expression. 0.5 times the length of the second arc portion <the length of the first arc portion <0.8 times the length of the second arc portion. The radius of the first arc portion is smaller than the radius of the second arc portion.

  In the present invention, in order to fix and stabilize the rotor in the mounting hole, an annular fixing groove is provided in the recess of the inner edge surface of the mounting hole, and when the rotor is installed in the mounting hole, the end face of the rotor is Connect to the inner groove wall of the fixed groove. The fixed body is installed in the fixed groove, and the fixed body is in contact with the end face of the rotor.

It is a systematic diagram of the linear actuator ball spline device of the present invention. It is an assembly figure of the linear actuator ball spline device of the present invention. It is sectional drawing of AA of FIG. It is a three-dimensional view of the rotor of the linear actuator ball spline device of the present invention. It is the structure schematic of the rotation path of the rotor of this invention. It is the structure schematic of the rotation path of the rotor of this invention, and is seen from the axial direction. 5 is a cross-sectional view taken along the line B-B in FIG. 5 to explain the detailed design of the rising portion of the circulation path.

  For a better understanding of the features and technical contents of the present invention, please refer to the description of the implementation method of the present invention and the drawings. However, this implementation method and drawings are for explanation and reference, and these do not impose any limitation on the present invention.

  1 to 3, the present invention is a kind of linear actuator / ball spline device, which includes a spline shaft (1), a moving body, and a rotor (3). including.

  The spline shaft (1) is an elongated structure extending in one direction, and this extension direction is defined as the axial direction (X), and a plurality of axial directions (X) are formed on the surface of the spline shaft (1). There is a ball rolling groove (11) installed along.

  The moving body includes a main body (2), two rotors (3), and a plurality of ball rolling elements (4). The body (2) has a through hole (21) that is paired with the spline shaft (1). There is a ball rolling tank (211) facing the ball rolling groove (11) on the inner edge surface of the through hole, and the ball rolling groove (11) and the ball rolling tank (211) are provided as one load passage. (90), and there are mounting holes (22) at both ends of the through hole (21). The diameter (D2) of the mounting hole (22) is larger than the diameter (D1) of the through hole (21). Big and both communicate with each other. The main body (2) has an opposing ball rolling tank (211) and a circulation hole (24) installed in parallel to the rolling tank (211). Both ends of the circulation hole (24) communicate with the mounting hole (22). The cross section of the circulation hole (24) is circular. That is, the radial direction of the circulation hole (24) is a sealed form. The two rotors (3) are accommodated in the two mounting holes (22), respectively. The rotor (3) has a rotating passage (31) of an opposing ball rolling tank (211). The outline of this circulation path (31) is U-shaped. Both ends thereof are connected to the load passage (90) and the circulation hole (24) to constitute a circulation passage (100). The plurality of ball rolling elements (4) are installed in the circulation passage.

  In this embodiment, in order to fix the rotor (3), an annular fixing groove (23) is provided in the recess of the inner edge surface of the mounting hole (22). When this rotor (3) is installed in the mounting hole (22), the end face (32) of the rotor (3) is aligned with the inner groove wall (231) of the fixed groove (23). After the fixed body (5) is installed in the fixed groove (23), the fixed body (5) comes into contact with the end face (32) of the rotor (3). This limits the degree of freedom in the axial direction (X) of the rotor (3). The fixed body (5) is a metal C-shaped clasp in this embodiment. Thereby, the rotor (3) is entirely covered with a metal material in an arbitrary direction. As shown in FIGS. 2 and 3, the longitudinal direction of the rotor (3) is covered by the mounting hole (22), and one end in the axial direction (X) of the rotor (3) is the end face of the fixed body (5). (32) is partially covered. The coverage is optimally more than half of the end face (32). The other end is placed facing the through hole (21) to avoid factors such as inappropriate use of the spline device. Also, if the ball rolling element (4) has an excessively large impact force on the circuit (31), it will cause the rotor (3) to burst (破: Most of the rotor is manufactured by plastic injection molding. Because) At that time, there is a metal stopper around the rotor (3), so that the rolling element (4) can be prevented from being separated from the circuit (31). Even if it was possible to avoid installing spline equipment, the rolling element (4) was completely detached from the main body (2) and spline shaft (1), and the equipment was originally restricted. Since the degree of freedom is lost, the related parts of the equipment collide with each other and are damaged. Therefore, in the present invention, by designing a special fixing structure of the rotor (3), it has a safety effect that spontaneously prevents the ball (referring to the ball rolling element) from bursting, and causes further damage. Avoid.

  3 to 7, in order to obtain better smoothness when the ball rolling element (4) moves in the circulation passage (100), the present invention divides the circulation path (31) into four parts. And the division of these four parts is connected according to the order, and is the rising part (A), the 1st rotation part (B), the 2nd rotation part (C), and the connection part (D). Among them, the rising portion (A) is connected to the load passage (90), and the connecting portion (D) is connected to the circulation hole (24). Referring to FIG. 7, a part of the rising portion (A) is stored in the ball rolling groove (11). The ascending part (A) has an ascending height (H) and an ascending length (C). The climb height (H) is smaller than the climb length (C), and the climb length (C) satisfies the following relational expression. 0.25 times the diameter of the rolling element ≤ rising length (C) ≤ 0.5 times the diameter of the rolling element. The first rotating part (B) and the second rotating part (C) constitute one rotating part, and the radius (R3) of the inner contour of this rotating part matches the following relational expression. 0.5 times the diameter of the rolling element ≤ inner contour radius (R3) ≤ diameter of the rolling element. Further, the width of the circular passage (31) is larger than the diameter of the rolling element (4).

  Referring to FIG. 6, the first rotating part (B) and the second rotating part (C) are viewed from the axial direction (X), and the first rotating part (B) and the second rotating part (C). Each bottom contour is formed by connecting the first arc part (B1) and the second arc part (C1) to each other, and it has a phase cut point (Q). The first arc portion (B1) and the second arc portion (C1) have different circular centers (B2, C2), and the length of the first arc portion (B1) matches the following relational expression. 0.5 times the second arc part (C1) <the length of the first arc part (B1) <0.8 times the length of the second arc part (C1).

  When the rolling element (4) reaches the first stage of the first rotating part (B), it continues to rise, so the length of the first arc part (B1) is the length of the second arc part (C1). The rising width of the first stage of the first rotating part (B) is slightly flat. Therefore, the rolling element (4) smoothly moves to the second rotating part (C), and a relatively flat rotating path (T) of the rolling element (4) can be obtained. Moreover, the radius (R1) of the first arc part (B1) is smaller than the radius (R2) of the second arc part (C1).

  According to the present invention, in the design of the ascending altitude required when the rolling element (4) leaves the rolling groove (11), the ascending altitude is increased by the ascending part (A) and the first rotating part ( Dispersed up to the previous stage of B), the rolling element (4) makes the ascending height of the ascending section (A) lower than the conventional design. The rising resistance force is relatively reduced, and the rolling element (4) can move smoothly when it leaves the rolling groove (11). Here, the former stage is calculated from the connection point of the rising part and the first rotating part, and is set to a range less than one half of the total length of the first rotating part.

1: Spline shaft
11: Rolling groove
2: Body
21: Through hole
211: Rolling tank
22: Mounting hole
23: Fixed tank
231: Inside tank wall
24: Circulation hole
3: Rotor
31: Circulation channel
32: End face
A: Ascending part
B: First rotating part
C: Second rotating part
D: Connection part
B1: Bottom contour of the first rotating part
C1: Bottom contour of the second rotating part
Q: Phase cut point
T: Rolling element rotation path
R1: Radius of the first arc part
R2: Radius of the second arc part
R3: Radius inner contour radius
U: Rotation path width
H: Ascent height
C: Ascending length
90: Load passage
100: Circulation path
X: Axial direction
4: Rolling element
5: Fixed body
D1: Diameter of the through hole
D2: Mounting hole diameter
B2, C2: Encentric

Claims (4)

A linear actuator ball spline device,
A spline shaft and a moving body,
The spline shaft is an elongated structure extending in one direction, and this extending direction is defined as the axial direction. A plurality of rolling grooves extending in the axial direction are formed on the surface of the spline shaft. Provided,
The moving body includes a main body, two rotors, and a plurality of rolling elements,
The main body has a through hole set with the spline shaft, and an inner edge surface of the through hole has a rolling tank corresponding to the rolling groove, and the rolling groove and the rolling tank have one load. There is a mounting hole at each end of the through-hole, and the diameter of the mounting hole is larger than the diameter of the through-hole and both communicate with each other. There is a circulation hole installed opposite to the rolling tank and parallel to the rolling tank, both ends of the circulation hole communicate with the mounting hole, and the cross section of the circulation hole is circular,
The two rotors are housed in the two mounting holes, respectively, and the rotor has a circulation channel facing the rolling tank, the contour of the circulation channel is U-shaped, and both ends thereof are respectively Connected to the load passage and the circulation hole to constitute one circulation passage,
The plurality of rolling elements are installed in the circulation passage,
The circular flow path is divided into four parts, and the four parts are connected in order to become a rising part, a first rotating part, a second rotating part, and a connecting part, and the width is larger than the diameter of the rolling element. Large linear actuator and ball spline device. The rising part with a portion is accommodated in the rolling groove, have a rise length a constant rise height, the elevated altitude less than increased length, and, the rising length of the rolling body or 0.25 times the diameter, and wherein said more than 0.5 times the diameter of the rolling body, the linear actuator ball spline device according to claim 1. Wherein and the second rotating portion and the first rotating portion to constitute one of the rotating portion, the radius of the inner contour of the rotating parts or 0.5 times the diameter of the rolling element, and less than or equal to the diameter of the rolling element The linear actuator / ball spline device according to claim 1, wherein   As seen from the axial direction of the first rotating part and the second rotating part, the contours of the bottoms of the first rotating part and the second rotating part are configured such that the first arc part and the second arc part are in contact with each other. The first arc part and the second arc part have different circle centers, and the length of the first arc part is greater than 0.5 times the length of the second arc part, and the length of the second arc part. 2. The linear actuator ball spline device according to claim 1, wherein the radius of the first arc portion is smaller than 0.8 times, and the radius of the first arc portion is smaller than the radius of the second arc portion.