TW201800674A - Ball spline shaft structure and manufacturing method thereof characterized by utilizing two sets of grinders to allow the circumference of the spline shaft to be formed with four ball grooves evenly distributed and spaced from each other with an included angle of 90 degrees - Google Patents

Abstract

A ball spline shaft structure and a manufacturing method thereof are disclosed. The spline shaft is sleeved on a ball sleeve, and the interior of the ball sleeve is disposed with balls capable of rolling in ball grooves formed on the circumference of the spline shaft, so that the ball sleeve is able to be axially displaced along the spline shaft. The spline shaft is formed as a round rod, and the circumference thereof is concavely formed with four ball grooves which are axially extended, and cross sections of the four ball grooves are evenly distributed on the circumference of the spline shaft and spaced from each other with an included angle of 90 degrees. Accordingly, two sets of grinders can be synchronously leaned toward the circumference of the spline shaft, and two grinding parts of the two sets of grinders are respectively served to grind for forming two ball grooves on the circumference at two sides of the spline shaft, thereby allowing the circumference of the spline shaft to be formed with four ball grooves evenly distributed and spaced from each other with an included angle of 90 degrees.

Description

Ball spline shaft structure and manufacturing method thereof

The present invention relates to a ball spline shaft, in particular to a ball bushing, which is used to roll a ball bushing in a ball groove of a spline shaft, so that the ball bushing is along the spline shaft. Structure of axially moving ball spline shaft and manufacturing method thereof.

The spline shaft is a linear guide member for movably sleeve a ball bushing. The inner hole wall of the ball bushing is provided with a plurality of balls arranged in a row. The ball is on the inner hole wall of the ball bushing and the peripheral surface of the spline shaft. Rolling between the ball grooves, so that the ball bushing and the spline shaft can move relatively axially. The conventional spline shaft structure is shown in Fig. 1. It is a spline shaft 10a adapted to high torque. On the circumferential surface of the spline shaft 10a, 120 ball grooves are evenly distributed at a uniform angle of 120 degrees. The groove 20a is used to provide the ball in the ball bushing to roll along the ball groove 20a. When the spline shaft 10a grinds the ball groove 20a on the circumferential surface, as shown in FIG. Grinding wheels 30 evenly distributed at an equal angle of 120 degrees are grinding at the same time, so special grinding tools composed of three sets of grinding wheels 30 are required. The three sets of grinding wheels 30 must be aligned to the same axis of the spline shaft 10a, which makes calibration very difficult. , So the entire process is more complicated.

In order to overcome the problems of difficult calibration and tedious process before the above-mentioned three groups of grinding wheels 30, the conventional method of improving the structure of the spline shaft is shown in FIG. 3, which is changed to two on the circumferential surface of the spline shaft 10b. Two ball grooves 20b are provided on each side. From the structure of the spline shaft 10b, the distance between the two ball grooves 20b on the same side is A, and the distance between the two ball grooves 20b on the same side is A. The distance is B, where the distance B is greater than the distance A. As shown in FIG. 4, as long as two sets of grinding wheels 40 are provided on the grinding tool, the two sides of the circumferential surface of the spline shaft 10 b can be ground and processed separately. The two ball grooves 20b are relatively easy to calibrate before grinding. However, concentrating the four ball grooves 20b on the two sides of the spline shaft 10b (that is, two ball grooves 20b on one side) is equivalent to applying grinding processing on only two sides of the spline shaft 10b, and grinding processing The temperature between the friction part between the middle grinding wheel and the spline shaft 10b is generally about 500-800 ° C, and the grinding heat is transmitted to the workpiece temperature caused by the spline shaft 10b, which causes uneven heating on the two sides and above and below. The situation will affect the shape and dimensional accuracy of the ball groove 20b, especially the tubular spline shaft with a through hole 101b at its axis, which is more likely to be affected.

In addition, referring to FIG. 5, if the spline shaft 10b is used to carry a load W1 in the vertical direction, the two ball grooves 20b are biased to the two sides of the spline shaft 10b, so only the center of the spline shaft 10b The two left and right ball grooves 20b above the line can be used to support the balls 60 of the ball bushing 50. The two ball grooves 20b below the center line have no load bearing effect, and the two left and right ball grooves 20b above are used to support the ball 60. The groove surface has only half of the arc surface, so its ability to carry radial load W1 is limited; and if the spline shaft 10b in FIG. 5 is rotated to 90 degrees and installed (as shown in FIG. 6), The groove surface of the two ball grooves 20b above the center line of the spline shaft 10b can support the load from the ball 60 (that is, the load W1 in the vertical direction), but the two ball grooves to the right of the center line of the spline shaft 10b The ability of 20b to resist lateral external forces or to carry horizontal load W2 is insufficient, and the ball groove 20b on the left side of the centerline of the spline shaft 10b in FIG. 6 cannot carry the horizontal load W2 from the right side, which causes many problems and applications in industrial applications. limits.

The object of the present invention is to provide a ball spline shaft structure and a manufacturing method thereof, which can improve the situation of uneven thermal strain caused by grinding the ball groove through the ball groove design of the circumferential surface of the spline shaft, and can evenly load the vertical direction. With the lateral load, and improve the precision of the spline shaft and simplify the grinding equipment and other purposes.

In order to achieve the above object, a preferred technical solution of the ball spline shaft structure of the present invention includes: the spline shaft is used to sleeve a ball bushing, and the balls inside the ball bushing are accommodated on the circumferential surface of the spline shaft; Rolling in the ball groove on the upper side causes the ball bush to move axially along the spline shaft, which is characterized in that the spline shaft is a round rod, and four axial directions are recessed on the circumferential surface of the spline shaft. The extended ball grooves, the four ball grooves are parallel to each other, and the four ball grooves are evenly distributed on the circumferential surface of the spline shaft at an angle of 90 degrees to each other in the cross-sectional direction.

In the above-mentioned ball spline shaft structure, the center of the spline shaft is provided with an axial through hole communicating with two ends.

In the above-mentioned ball spline shaft structure, the ball groove is a semi-circular arc or a Goth arc groove.

In order to achieve the above object, the method for manufacturing a ball spline shaft structure of the present invention, the preferred technical solution includes: (a) fixing a spline shaft on a grinding machine, and the grinding device is provided on two sides of the spline shaft The two sets of rotating grinding wheels each have two grinding parts protruding from the circumferential surface of the grinding wheel, and the distance between the two grinding parts is equal to a distance of 90 degrees between the two ball grooves; (b) the The spline shaft is conveyed and moved in the axial direction of the spline shaft by the conveying table of the grinding tool, and the intermediate point between the two grinding parts is aligned with the center of the spline shaft; (c) the two sets of grinding wheels Leaning against the spline shaft synchronously, the two grinding parts of the two sets of grinding wheels were respectively ground on the circumferential surface on the two sides of the spline shaft to form two ball grooves, thereby forming four circumferential surfaces of the spline shaft. The ball grooves are evenly distributed at an angle of 90 degrees with each other.

According to the ball spline shaft structure and the manufacturing method of the invention, the angle between the four grooves of the ball is 90 degrees, and the following effects can be achieved:

(1) The grinding process is simplified and the cost is reduced: the angle between the four grooves of the ball groove on the circumferential surface of the spline shaft of the present invention is 90 degrees, so two sets of grinding wheels can be used from the spline shaft. Grinding is performed on two sides, and the two grinding sections of each group of wheels can grind two ball grooves on one side, avoiding the grinding process of the conventional three groups of wheels, which overcomes the tedious problem of calibration operations. A total of four ball grooves of the spline shaft can be ground in one operation, thereby achieving the effect of simplifying the grinding process and reducing manufacturing costs.

(2) Improve the situation of uneven thermal strain caused by grinding ball grooves: The angle between the four grooves of the ball groove on the circumferential surface of the spline shaft according to the present invention is 90 degrees, and when two sets of grinding wheels are grinding When cutting, the four points on the circumferential surface of the spline shaft are ground at an average angle of 90 degrees, so as to overcome the uneven thermal strain of the conventional spline shaft during grinding, and achieve the effect of improving the accuracy of the ball groove.

The structural features and other functions and purposes of the present invention are described in detail with reference to the embodiments of the drawings as follows:

Referring to FIG. 7 and FIG. 8, a preferred embodiment of the ball spline shaft structure of the present invention includes: a spline shaft 1 for providing a ball bushing 50 linearly sleeved, the spline shaft 1 It is a solid round rod, or a pipe body with an axial through hole 11 communicating with two ends in the center; in particular, referring to FIG. 7 and FIG. 10 together, the spline shaft 1 is provided with four recesses on the circumferential surface. The ball grooves 12 extending in the axial direction, the four ball grooves 12 are parallel to each other, and the four ball grooves 12 are evenly distributed on the circumferential surface of the spline shaft 1 at an angle of 90 degrees to each other in the cross-sectional direction. Each of the ball grooves 12 is a semi-circular arc or a Gothic arc groove, thereby forming a spline shaft 1 that provides a linear movable sleeve of the ball bushing 50; referring to FIG. 7 and FIG. 9 together, when When the ball bushing 50 is sleeved on the spline shaft 1, the four rows of balls 60 inside the ball bushing 50 are accommodated in the four ball grooves 12 on the peripheral surface of the spline shaft 1 to roll, The ball bushing 50 can move axially along the spline shaft 1.

Referring to FIG. 11 again, the method for manufacturing a spline shaft according to the present invention, a preferred embodiment thereof includes: fixing a spline shaft 1 on a grinding machine, and the spline shaft 1 is axially conveyed by the grinding machine Moving, the grinding device is provided with two sets of grinding wheels 40 rotating on the two sides of the spline shaft 1, the circumferential surface of each grinding wheel 40 protrudes from two grinding portions 401, and the distance C between the two grinding portions 401 is equal to two The angle between the two ball grooves 12 is a distance D of 90 degrees, and the intermediate point between the two grinding portions 401 is aligned with the center of the spline shaft 1, so that the two sets of grinding wheels 40 are simultaneously moved toward each other. On the two sides of the spline shaft 1, the two grinding portions 401 of the two sets of grinding wheels 40 are respectively polished on the circumferential surface of the two sides of the spline shaft 1 into the two ball grooves 12, so that the spline shaft 1 is further grounded. Four ball grooves 12 are formed on the circumferential surface of the ball grooves at an angle of 90 degrees.

The ball spline shaft structure and the manufacturing method thereof of the present invention can be applied to a vertical shaft (not shown) at the end of a horizontal joint robotic arm (SCARA). The ball bushing 50 drives the spline shaft 1 and the gripper to rotate ( In other fields of application, the ball bushing 50 can be driven by the spline shaft 1), and the balls 60 in the ball bushing 50 can roll along the ball grooves 12, so the spline shaft 1 and the The ball bushing 50 moves relatively linearly; and when the spline shaft 1 rotates under a radial torsion, the above-mentioned four ball grooves are arranged in an average manner, and the torque is evenly applied to the circumference of the spline shaft 1 The result of average stress will be able to extend its service life. Furthermore, the present invention can use two sets of grinding wheels 40 to grind the ball grooves 12 from the two sides of the spline shaft 1. Compared with the traditional three-group grinding wheel 30 processing method, the processing machine of the present invention is easier to prepare and does not require Dedicated machines can be used for production. In addition to reducing manufacturing costs, the industry's competitiveness has made full progress and has strong industrial competitiveness. In addition, in the manner that four ball grooves 12 are ground and fed simultaneously by the two opposite grinding wheels 40, the forming accuracy of each ball groove 12 can be more easily controlled, so its precision will be improved compared to the traditional processing method. .

According to the present invention, the four ball grooves 12 of the spline shaft 1 are distributed on the circumferential surface at an average angle of 90 degrees. The vertical load W1 and the horizontal (transverse) load W2 can be carried on average regardless of the installation application direction. In detail, as shown in FIG. 9, it is assumed that the four ball grooves 12 at the time of installation and application are at a first angle (similar to the cross-sectional direction of the cross-section), and the entire groove surface of the uppermost ball groove 12 is Can withstand the vertical load W1 from the ball 60, and the 1/2 groove surface of the ball groove 12 on the two sides (the total is equal to one groove surface) can also withstand the vertical load W1 from the ball 60; if it is a horizontal load W2, no matter which direction is left and right, all the groove surfaces of the ball groove 12 on one side can bear the horizontal load W2 from the ball 60, and the 1/2 groove surface of the upper and lower ball grooves 12 (the total is equal to One full groove surface) can also withstand the horizontal load W2 from the balls 60, so the mechanical strength of the two-way load W1 and W2 is the same. As shown in FIG. 12, it is assumed that the four ball grooves 12 are installed at a second angle when the application is installed (that is, the spline shaft 1 in FIG. 12 is rotated 90 degrees again, and the cross-section direction is similar to the state of the X-shape arrangement). Regardless of the vertical load W1 or the horizontal load W2, all the groove surfaces of the two ball grooves 12 can be used to bear the loads W1 and W2 from the balls 60. The strength of the two-way load W1 and W2 is also the same. The inventive spline shaft 1 is more advanced than the conventional second type spline shaft shown in FIGS. 3 to 6.

In summary, the ball spline shaft structure and its manufacturing method of the present invention are indeed practical and creative, and the use of its technical means is also novel and undoubted, and its efficacy is in line with the purpose of the invention, which has been called a reasonable progress. To Ming. To this end, an application for an invention patent was filed in accordance with the law, but I would like to ask Jun Bureau for detailed review and to grant the patent as a prayer.

[Learning section]
10a, 10b ‧‧‧ spline shaft
20a, 20b ‧‧‧ Ball groove
30, 40‧‧‧ Grinding wheels
A, B‧‧‧ distance
[this invention]
1‧‧‧ spline shaft
11‧‧‧Axial through hole
12‧‧‧ball groove
40‧‧‧ Grinding wheel
401‧‧‧Grinding Department
50‧‧‧ball bush
60‧‧‧ball
C, D‧‧‧distance
W1‧‧‧Vertical load
W2‧‧‧Horizontal load

FIG. 1 is a schematic diagram of an end structure of a conventional first type spline shaft. FIG. 2 is a schematic diagram of the grinding process of the first spline shaft of FIG. 1. FIG. 3 is a schematic diagram of an end structure of a conventional second type spline shaft. FIG. 4 is a schematic diagram of the grinding process of the second type spline shaft of FIG. 3. FIG. 5 is a schematic diagram of the vertical load of the second type of spline shaft of FIG. 3. 6 is a schematic diagram of vertical and lateral loads after the second type spline shaft of FIG. 3 is rotated by 90 degrees. FIG. 7 is a perspective view of a combination of a spline shaft and a ball bush according to the present invention. FIG. 8 is a schematic side view of a combination of a spline shaft and a ball bush according to the present invention. FIG. 9 is a schematic view showing the combination of a spline shaft and a ball bushing and bearing load according to the present invention. FIG. 10 is a schematic sectional view of a spline shaft according to the present invention. FIG. 11 is a schematic diagram of a grinding process of a spline shaft according to the present invention. FIG. 12 is a schematic diagram of a load of a spline bearing according to the present invention.

1‧‧‧ spline shaft

11‧‧‧Axial through hole

12‧‧‧ball groove

50‧‧‧ball bush

Claims (4)

The utility model relates to a ball spline shaft structure. The spline shaft is used to sleeve a ball bushing, and the balls inside the ball bushing are accommodated in ball grooves on the circumferential surface of the spline shaft to roll the ball bushing along The spline shaft moves axially, and is characterized in that the spline shaft is a round rod, and four circumferentially extending ball grooves are recessed on a circumferential surface of the spline shaft, and the four ball grooves are mutually Parallel, and the four ball grooves are evenly distributed on the circumferential surface of the spline shaft at an included angle of 90 degrees to each other in the cross-sectional direction. The ball spline shaft structure according to claim 1, wherein the center of the spline shaft is provided with an axial through hole communicating with two ends. The ball spline shaft structure according to claim 1, wherein the ball groove is a semi-circular arc or a Gothic arc groove. A method for manufacturing a ball spline shaft structure according to claim 1, 2 or 3, comprising: (a) fixing a spline shaft on a grinding machine, and the grinding device is provided on two sides of the spline shaft The two sets of rotating grinding wheels each have two grinding parts protruding from the circumferential surface of the grinding wheel, and the distance between the two grinding parts is equal to a distance of 90 degrees between the two ball grooves; (b) the The spline shaft is conveyed and moved in the axial direction of the spline shaft by the conveying table of the grinding tool, and the intermediate point between the two grinding parts is aligned with the center of the spline shaft; (c) the two sets of grinding wheels Leaning against the spline shaft synchronously, the two grinding parts of the two sets of grinding wheels were respectively ground on the circumferential surface on the two sides of the spline shaft to form two ball grooves, thereby forming four circumferential surfaces of the spline shaft. The ball grooves are evenly distributed at an angle of 90 degrees with each other.