TW201413128A - Processing method for grinding inner ball groove of outer tube of ball spline assembly - Google Patents

Abstract

A processing method for grinding inner ball grooves of an outer tube of a ball spline assembly includes the steps of forming a plurality of ball retained structure on an inner wall of the outer tube and grinding each of the ball retained structures to form the inner ball grooves.

Description

Grinding processing method for inner bead groove of ball spline group outer cylinder

The invention relates to a method for grinding and grinding a bead groove in an outer cylinder of a ball spline group.

In the various ball spline groups, the outer cylinder plays a central role and must have sufficient rigidity to provide the bearing capacity and the impact force generated when the ball is moved. On the other hand, the structure has extremely high precision requirements. To avoid the poor performance of the overall components, or to generate abnormal noise.

1 is a main component of a conventional ball spline group 1, which includes a spline shaft 11, an outer cylinder 12, an end cap 13, a ball retainer 14, and balls 15 that circulate between the components, and a dustproof member. 16 is disposed on the end cover 13. Among them, the ball retainer 14 is disposed between the spline shaft 11 and the outer cylinder 12, so that the ball 15 can maintain its position to avoid falling before assembly or when the outer cylinder 12 is separated from the spline shaft 11. However, the ball retainer 14 is made of a plastic material having a weak strength. When the ball 15 is subjected to the cyclic motion for a long period of time, it is easily damaged, which may cause vibration of the ball 15 during movement, and is particularly high in the ball 15 During exercise, the probability of the ball 15 falling off is increased, causing a risk of user operation.

The above situation is more severe as the size of the ball spline group 1 increases. Since the ball retainer 14 of the large ball spline group 1 has a long length, the number of the balls 15 in the middle portion is increased, and is far from the support point, and the rigidity is insufficient, and it is easily deformed or twisted.

In addition, since the inner bead groove 121 of the outer cylinder 12 must directly carry the high-speed movement of the ball 15, the accuracy of the inner bead groove 121 is relatively high. Further, in the conventional outer cylinder 12, the processing of the bead groove 121 is a grinding process, and a large amount of heat is generated in the polishing process, and the precision of the inner bead groove 121 is broken. In addition, in order to meet the high precision requirements of the inner bead groove 121, the conventional grinding process can only perform angle adjustment and operation one by one for each inner bead groove 121, so the general polishing process system is quite complicated and slow, and the manufacturing cost is also high. .

Therefore, how to provide a ball bead grinding method for a ball spline group outer cylinder, which has a simple manufacturing process, is easy to process and assemble, and can form a high-precision and high-reliability inner bead groove to reduce the production of the ball spline group. Cost and improved operational stability have become an important issue.

In view of the above problems, an object of the present invention is to provide a method for polishing a bead groove in an outer cylinder of a ball spline group, which eliminates the need for a ball retainer, reduces the number of assembled components, and simplifies the assembly process. Reducing the grinding requirement when forming the inner bead groove is beneficial to making the inner bead groove with high precision and high reliability, so as to improve the production yield and operational stability of the ball spline group.

In order to achieve the above object, a method for polishing a bead groove in an outer cylinder of a ball spline group according to the present invention comprises the steps of: forming a plurality of ball retaining structures on an inner wall surface of the outer cylinder; and grinding each ball retaining structure to form a Inner bead ditch.

In an embodiment of the invention, the ball retaining structure has a surface on the inner wall There is a first opening having a diameter smaller than a diameter of a plurality of balls of the ball spline group.

In an embodiment of the invention, each of the ball retaining structures is in the shape of an inverted bag.

In one embodiment of the invention, the ball retaining structure is formed in a broaching, wire cutting, discharging or draw forming process.

In an embodiment of the invention, the ball retaining structure has a plurality of non-ball contact portions.

In an embodiment of the invention, each of the ball retaining structures has an upper non-ball contact portion, a left non-ball contact portion, and a right non-ball contact portion, and the left non-ball contact portion and the right non-ball contact portion are symmetric. .

In an embodiment of the invention, the grinding process further comprises the step of adding a coolant or a lubricating fluid to the non-ball contact.

In an embodiment of the invention, in the step of grinding the respective ball retaining structures, at least one inner recess of each of the ball retaining structures is ground and removed.

In an embodiment of the invention, each of the ball retaining structures has two recesses, and at the same time, the inner recesses are removed during grinding.

In an embodiment of the invention, the inner recess is ground to form a ball contact.

According to the present invention, in the method of grinding the inner bead groove of the ball spline group, the ball retaining structure is formed on the inner wall surface of the outer cylinder by a non-abrasive processing method such as broaching, etc., and then Grinding each ball retaining structure to form an inner bead groove, so that the inner wall surface of the outer cylinder can provide ball retaining effect, reduce the number of assembled parts, and eliminate the use of ball retainers The problem of insufficient strength rigidity that may occur is particularly advantageous for the use of large ball spline groups.

Moreover, in the above two-stage method, since the preliminary ball retaining structure is formed by the non-polishing method, and the characteristics of the ball retaining structure are retained, the inner bead groove can be formed by simply grinding, so that the grinding can be avoided. The problem of deformation, thereby improving the accuracy, and also shortening the processing time increased by the entire grinding process.

Compared with the conventional method of grinding only, the two-stage method can reduce the grinding area, reduce the probability of occurrence of the vibrating knife, and also does not produce excessive heat affecting the accuracy of the inner bead groove, ensuring the ball spline. The stability and reliability of the group at high speed operation. In addition, the ball retaining structure formed by the present invention can have a non-ball contact portion, and is suitable as a place for adding a coolant or a lubricating fluid, and can also reduce the thermal energy crisis generated by the grinding process and enhance the smoothness of the ball rotation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of grinding a bead groove in an outer cylinder of a ball spline set according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings, wherein like elements will be described with the same reference numerals.

2A is a flow chart showing the steps of a grinding process for a ball groove in an outer cylinder of a ball spline group according to an embodiment of the present invention, and FIG. 2B is an exploded view of the ball spline group obtained by the process shown in FIG. 2A. Please refer to FIG. 2A and FIG. 2B at the same time. The ball spline set 2 includes a spline shaft 21, an outer cylinder 22, an end cover 23, a dust guard 24, and a cyclic movement of the elements Ball 25 between pieces. The outer tube 22 is sleeved on the spline shaft 21, and the end cover 23 is assembled on the two ends of the outer tube 22. The dustproof sheet 24 is disposed on the end cover 23. The method for polishing the inner bead groove of the ball spline group of the present embodiment may include the steps of: forming a plurality of ball retaining structures on the inner wall surface of the outer cylinder (S10); and grinding the ball retaining structures to form an inner portion Pearl groove (S20).

3 is a cross-sectional view of the outer cylinder and its ball retaining structure shown in FIG. 2B, which is shown in FIG. 3. The outer cylinder 22 is a tubular metal member that is open at both ends before being processed, and has an inner wall surface 221 and an outer wall surface 222. In addition, the outer cylinder 22 can also be referred to as a spline nut. In step S10, the inner wall surface 221 of the outer cylinder 22 forms a plurality of ball retaining structures 223, wherein the ball retaining structure 223 is formed by processing such as but not limited to broaching, wire cutting, discharging or drawing. These processing methods are faster and more economical than grinding, especially in the case of broach cutting, which has the advantages of faster speed and lower cost.

The ball retaining structure 223 has no particular configuration limitation, and is based on the principle of engaging an opening of the ball 25 and having an opening smaller than the diameter of the ball 25. As shown in FIG. 2B, the ball retaining structure 223 may be elongated and penetrate both ends of the outer cylinder 22.

However, preferably, the ball retaining structure 223 may have an inverted shape as shown in this embodiment. The inverted packet shape may have a plurality of notches, and as shown in FIG. 3, the ball retaining structure 223 has three projections. However, it should be particularly noted that the term "reverse package structure" as used herein is merely a name indicating the structure shown in FIG. 3. Others having the same or similar structure but different names are also covered by the present invention. range.

The ball retaining structure 223 has a first opening 224 on the inner wall surface 221, and the diameter of the first opening 224 is smaller than the diameter D of the ball 25 of the ball spline group 2 (please first) Referring to Fig. 5), therefore, when the ball 25 is accommodated in the prepared outer cylinder 22, the ball 25 does not fall off even if the ball cage is not used, and the detailed description will be described later with reference to Fig. 5.

4A is a schematic view of the polishing performed in the step S20 shown in FIG. 2A, and FIG. 4B is a partially enlarged schematic view of FIG. 4A, and please refer to FIG. 3, FIG. 4A and FIG. 4B at the same time. In step S20, each of the ball holding structures 223 is ground to remove the inner concave portion 225 of each of the ball holding structures 223 to form an inner bead groove 226. In order to highlight the difference between before and after the grinding, FIG. 4A shows the two ball retaining structure 223 before grinding and the two inner bead grooves 226 after grinding, wherein the inner concave portion 225 in the ball retaining structure 223 is ground to form the inner bead groove 226. Ball contact portion 227.

According to the method for polishing the inner bead groove of the ball spline group of the present invention, the inner bead groove 226 is processed in two stages, so that the grinding tool 3 only needs to grind the inner concave portion 225 during grinding. Knowing the full grinding process, not only the resistance is small, the probability of vibrating the knife is reduced, and the requirement of grinding the entire ball contact curvature is not required. The grinding tool 3 does not need to frequently adjust the angle, so the time required for processing can be shortened. .

The abrasive tool 3 can be, for example but not limited to, a grinding wheel, except that the width W of the abrasive tool 3 must be smaller than the diameter D of the ball (shown in Figure 5), but not necessarily smaller than the diameter of the first opening 224. Therefore, after the inner bead groove 226 is formed, a second opening 228 is formed on the inner wall surface 221 (Fig. 5)), and the diameter of the second opening 228 is equal to the diameter of the first opening 224 or approaches the width W of the abrasive tool 3. In the present embodiment, the diameter of the first opening 224 of the ball retaining structure 223 is between the width W of the grinding tool 3 and the diameter D of the ball 25 (shown in FIG. 4B), so the inner bead formed after grinding The diameter of the second opening 228 of the groove 226 is equal to the diameter of the first opening 224.

4C is an enlarged schematic view showing another embodiment of the inner bead groove shown in FIG. 4B, which is also referred to FIG. 4A and FIG. 4C. If the diameter of the first opening 224 is smaller than the width W of the abrasive tool 3 (shown in FIG. 4C) when the ball retaining structure 223 is formed, the diameter of the second opening 228 of the inner bead groove 226 formed after the grinding is It is larger than the diameter of the first opening 224 and approaches the width W of the grinding tool 3, and since the width W of the grinding tool 3 is still smaller than the diameter D of the ball 25 (shown in FIG. 5), even if the ball retainer is not used, When the ball 25 is placed in the inner bead 226, the ball 25 does not fall off as well.

In general, according to the grinding method of the inner bead groove of the ball spline group of the present invention, the inner bead groove is prepared, and the inner bead groove and the ball retainer of the outer tube of the ball spline group are provided, There is no need to use additional ball cages, which simplifies the assembly process and reduces assembly procedures and assembly accuracy.

Fig. 5 is a schematic cross-sectional view showing the outer cylinder of the ball-and-groove group in the outer cylinder of the ball spline group according to the present invention applied to the ball spline group, as shown in Fig. 5. The inner bead groove 226 of the outer cylinder 22 and the track groove 211 of the spline shaft 21 together form a ball passage to accommodate the ball 25, and the outer cylinder 22 and the flower The gap between the key shafts 21 may be from 0.05 mm to 1 mm. Since the second opening 228 of the inner bead 226 is smaller than the diameter D of the ball 25, even if the outer cylinder 22 is separated from the spline shaft 21, the ball 25 does not fall, so that it is not necessary to add a plastic ball retainer, and The outer cylinder 22 is made of a relatively rigid metal material, and the bearing force of the ball 25 at a high speed is superior to that of the conventional ball cage.

Further, the inner bead groove 226 has a plurality of projections which are non-ball contact portions 229. Moreover, the non-ball contact portions 229 can be respectively divided into an upper non-ball contact portion 229a, a left non-ball contact portion 229b, and a right non-ball contact portion 229c according to the azimuth relationship, and the left non-ball contact portion 229b and the right non-ball contact portion. The 229c system is symmetrical. Since the ball 25 and the inner bead groove 226 are only in contact with the ball contact portion 227 at two points, and the upper non-ball contact portion 229a, the left non-ball contact portion 229b, and the right non-ball contact portion 229c are left, the end cap can be used. The design of the oil filling hole is used as a space or passage for oil storage after the lubricating fluid is input to improve the smoothness of the ball 25 when moving.

It should be particularly noted that the outer cylinder 22 formed by the inner ball groove grinding method of the ball spline group of the present invention can also be used in combination with the ball cage to strengthen the ball 25 in the ball spline group. GPS.

In summary, according to the present invention, a method for grinding a bead groove in an outer cylinder of a ball spline group is formed by a non-abrasive processing method such as broaching and broaching on the inner wall surface of the outer cylinder, and then a ball retaining structure is formed. Grinding each ball retaining structure to form an inner bead groove, so that the inner wall surface of the outer cylinder can provide ball retaining effect, reduce the number of assembled parts, and eliminate the problem of insufficient strength rigidity which may occur with the ball retainer, which is particularly advantageous Large ball spline group is used.

Moreover, in the above two-stage method, since the preliminary ball retaining structure is formed by the non-polishing method, and the characteristics of the ball retaining structure are retained, the inner bead groove can be formed by simply grinding, so that the grinding can be avoided. The problem of deformation, thereby improving the accuracy, and also shortening the processing time increased by the entire grinding process.

Compared with the conventional method of grinding only, the two-stage method can reduce the grinding area, reduce the probability of occurrence of the vibrating knife, and also does not produce excessive heat affecting the accuracy of the inner bead groove, ensuring the ball spline. The stability and reliability of the group at high speed operation. In addition, the ball retaining structure formed by the present invention can have a non-ball contact portion, and is suitable as a place for adding a coolant or a lubricating fluid, and can also reduce the thermal energy crisis generated by the grinding process and enhance the smoothness of the ball rotation.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

1, 2‧‧‧ ball spline group

11, 21‧‧‧ spline shaft

12, 22‧‧‧ outer cylinder

121, 226‧‧‧ Neizhugou

13, 23‧‧‧ end caps

14‧‧‧Ball retainer

15, 25‧‧‧ balls

16, 24‧‧‧Dust parts

211‧‧‧ Track slot

221‧‧‧ inner wall

222‧‧‧ outer wall

223‧‧‧Ball retention structure

224‧‧‧ first opening

225‧‧‧ Inside recess

227‧‧‧Road contact

228‧‧‧second opening

229‧‧‧Non-ball contact

229a‧‧‧Non-ball contact

229b‧‧‧Left non-ball contact

229c‧‧‧Right non-ball contact

3‧‧‧ grinding tools

D‧‧‧diameter

S10~S20‧‧‧Steps

W‧‧‧Width

1 is a schematic view of a conventional ball spline group; FIG. 2A is a flow chart showing the steps of a grinding process for a ball groove in an outer cylinder of a ball spline group according to an embodiment of the present invention; FIG. 2B is a view according to FIG. The schematic diagram of the decomposition of the ball spline group obtained by the step processing; FIG. 3 is a schematic cross-sectional view of the outer cylinder and the ball retaining structure thereof shown in FIG. 2B; 4A is a schematic view showing the polishing performed in the step S20 shown in FIG. 2A; FIG. 4B is a partially enlarged schematic view showing the embodiment shown in FIG. 4A; and FIG. 4C is an enlarged schematic view showing another embodiment of the inner bead groove shown in FIG. 4B; Fig. 5 is a cross-sectional view showing the outer cylinder of the ball spline group in the inner cylinder of the ball spline group applied to the ball spline group according to the present invention.

S10~S20‧‧‧Steps

Claims (10)

A method for grinding a bead groove in an outer cylinder of a ball spline group, comprising the steps of: forming a plurality of ball retaining structures on an inner wall surface of the outer cylinder; and grinding each of the ball retaining structures to form an inner bead groove. The grinding processing method of claim 1, wherein each of the ball retaining structures has a first opening on the inner wall surface, the first opening having a smaller diameter than the plurality of balls of the ball spline group. The grinding processing method of claim 1, wherein each of the ball retaining structures has an inverted shape. The grinding processing method according to claim 1, wherein the ball retaining structure is formed by a broaching, wire cutting, discharging or drawing forming process. The method of grinding according to claim 1, wherein each of the ball retaining structures has a plurality of non-ball contact portions. The grinding processing method of claim 5, wherein each of the ball retaining structures has an upper non-ball contact portion, a left non-ball contact portion, and a right non-ball contact portion, and the left non-ball contact portion and The right non-ball contact portion is symmetrical. The grinding processing method of claim 5, further comprising the step of: adding a cooling liquid or a lubricating liquid to the non-ball contact portions. A grinding processing method as described in claim 1, wherein In the step of grinding each of the ball retaining structures, at least one inner recess of each of the ball retaining structures is ground and removed. The method of polishing according to claim 8, wherein each of the ball retaining structures has two inner recesses, and at the time of grinding, the inner recesses are simultaneously removed. The method of grinding according to claim 8, wherein the inner concave portion is ground to form a ball contact portion.