Mandrel applied to ball assembly in ball screw

Abstract

The utility model discloses a mandrel applied to ball assembly in a ball screw, which comprises a mandrel body, the front end of the mandrel body is provided with a spiral groove, the rear end of the mandrel body is provided with a polished shaft, the spiral groove is divided into three sections, namely a first spiral groove section, a second spiral groove section and a third spiral groove section in sequence, the pitch diameter of the first spiral groove section is between the pitch diameter of a lead screw and the pitch diameter of a ball circulator positioning boss, the pitch diameter of the second spiral groove section is gradually changed, the pitch diameter of the third spiral groove section is smaller than the pitch diameter of the lead screw, a conical notch is formed in the end face of the spiral groove end of the mandrel body, and a section of conical flow guide groove is formed in the bottom of the conical notch. When the ball is assembled, the concentricity of the mandrel and the nut does not need to be manually controlled, the assembling difficulty and the labor intensity are reduced, the situation that the ball escapes due to the fact that the mandrel is separated from the nut can be prevented, guiding can be provided for assembling of the ball, and the phenomena of wrong assembling, ball clamping and the like are reduced; and the phenomenon that the balls are scattered all around due to unstable hands during assembly can be prevented.

Description

Technical Field

[0001] The utility model belongs to the technical field of ball screw assembly, and particularly relates to a mandrel applied to the assembly of balls in a ball screw. Background Art

[0002] A ball screw is a component that converts rotational motion into linear motion, and in some specific situations, it can also convert linear motion into rotational motion. Since the transmission unit therein is a ball, the contacts with the screw and the nut during the transmission process are all point contacts and are rolling frictions, so the ball screw has a very high transmission efficiency. In addition, the ball screw also has characteristics such as high rotational speed and high precision. Therefore, the ball screw has a wide range of applications in the fields of automated industry, aerospace industry, precision machine tools, and automotive braking, etc.

[0003] A ball screw generally includes parts such as a screw, a nut, balls, and a ball circulator. The balls move infinitely in a circular motion in the nut spiral groove by climbing over the screw under the action of the circulator. Among them, the assembly of the balls is a major difficulty in the assembly of the ball screw. The traditional method is to use a smooth rod to replace the screw for assembling the balls. This method requires a certain degree of proficiency, has a high installation threshold, and is not conducive to getting started quickly. In addition, since it is necessary to keep the smooth rod and the nut concentric during installation, one arm of the operator needs to hold the smooth rod and the nut at the same time and maintain a posture for a long time. After assembling for a period of time, phenomena such as sore arms and mental fatigue will occur. The resulting consequences are that the balls often scatter, are misassembled, or there are fewer balls during the installation process, greatly reducing the assembly efficiency and indirectly increasing the production cost.

[0004] Therefore, how to solve the defects existing in the above-mentioned prior art has become the direction of efforts of those skilled in the art. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a mandrel applied to the assembly of balls in a ball screw, which can completely solve the deficiencies of the above-mentioned prior art.

[0006] The purpose of the utility model is achieved by the following technical solutions:

[0007] A mandrel applied to the assembly of balls in a ball screw includes a mandrel body. A spiral groove is provided at the front end of the mandrel body, and the rear end is a smooth shaft. The spiral groove is divided into three sections, namely the first spiral groove section, the second spiral groove section, and the third spiral groove section. The mean diameter of the first spiral groove section is between the mean diameters of the screw and the positioning boss of the ball circulator. The mean diameter of the second spiral groove section is a gradually changing mean diameter. The mean diameter of the third spiral groove section is smaller than the mean diameter of the screw. A conical notch is provided at the end face of the spiral groove end of the mandrel body, and a section of conical diversion groove is provided at the bottom of the conical notch.

[0008] Further, the mean diameter of the second helical groove section gradually changes from 0.5 mm smaller than the mean diameter of the lead screw to 0.1 mm smaller than the mean diameter of the lead screw.

[0009] Further, the mean diameter of the third helical groove section is 0.1 mm smaller than the mean diameter of the lead screw.

[0010] Further, the angle of the conical notch is 140° to 160°.

[0011] Further, the taper of the conical flow guide groove is 3° to 6°.

[0012] Further, the diameter of the conical flow guide groove is 0.1 mm to 0.2 mm larger than the diameter of the ball.

[0013] Further, the diameter of the optical axis is 0.1 mm to 0.2 mm smaller than the bottom diameter of the lead screw helical groove.

[0014] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0015] 1. When assembling the balls, there is no need for manual control of the concentricity of the mandrel and the nut, which reduces the assembly difficulty and labor intensity. Even without assembly experience, one can quickly get started, improving the assembly efficiency;

[0016] 2. One end of the mandrel is provided with a helical groove, which can prevent the mandrel from separating from the nut and causing the balls to escape, and can also provide guidance for the assembly of the balls, reducing misassembly, ball jamming and other phenomena;

[0017] 3. A conical notch is provided at the end face of the helical groove of the mandrel, which can prevent the balls from scattering due to unsteady hands during assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic three-dimensional structure diagram of the present utility model;

[0019] Figure 2 is a sectional view of the present utility model;

[0020] Figure 3 is a schematic diagram of assembling the balls of the present utility model;

[0021] Figure 4 is a schematic diagram of the mean diameters of the three helical grooves of the present utility model;

[0022] Figure 5 is a schematic three-dimensional structure diagram of the ball circulator in the present utility model;

[0023] Figure 6 is a schematic three-dimensional structure diagram of the ball circulator from another angle in the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The present utility model will be further described below in conjunction with specific embodiments and the accompanying drawings.

[0025] As Figures 1 to 6 shown, a mandrel applied to the ball assembly in a ball screw includes a mandrel body. A spiral groove 1 is provided at the front end of the mandrel body, and the rear end is a smooth shaft 2. The number of starts and the pitch of the spiral groove 1 are the same as those of the screw. The spiral groove 1 is divided into three sections, namely the first spiral groove section 101, the second spiral groove section 102, and the third spiral groove section 103. The pitch diameter of the first spiral groove section 101 is between the pitch diameter of the screw and the pitch diameter of the positioning boss 3 of the ball circulator. That is, only the positioning boss 3 of the ball circulator can pass through this section of the spiral groove, and the ball 8 cannot enter this section. This can prevent the ball 8 from mistakenly entering this section during assembly, resulting in misassembly. At the same time, after the positioning boss 3 of the ball circulator enters this section, it can provide radial and axial support for the mandrel, solving the problem of the need for manual control of the concentricity between the mandrel and the nut. The pitch diameter of the second spiral groove section 102 is a gradually changing pitch diameter. Specifically, the pitch diameter of the second spiral groove section 102 transitions and gradually changes from 0.5 mm smaller than the pitch diameter of the screw to 0.1 mm smaller than the pitch diameter of the screw. The function of this section is to provide guidance for the flow of the ball 8, making it easier for the ball 8 to flow into the spiral groove of the nut 9. The pitch diameter of the third spiral groove section 103 is 0.1 mm smaller than the pitch diameter of the screw, aiming to enable the ball 8 to smoothly transition to the smooth shaft 2. A conical notch 4 is provided at the end face of the spiral groove 1 end of the mandrel body. The angle of the conical notch 4 is 140° to 160°. A conical diversion groove 5 is provided at the bottom of the conical notch 4. The taper of the conical diversion groove 5 is 3° to 6°. The diameter of the conical diversion groove 5 is 0.1 mm to 0.2 mm larger than the diameter of the ball 8.

[0026] In this embodiment, the diameter of the smooth shaft 2 is 0.1 mm to 0.2 mm smaller than the bottom diameter of the screw spiral groove, aiming to enable the nut 9 to freely slide on the mandrel when the screw is replaced with the mandrel, facilitating the ball 8 to be screwed into the screw. The spiral groove 1 of this mandrel can be processed by turning or grinding. The top conical notch 4 is processed by turning, and the conical diversion groove 5 is processed by ball-end milling. The processing difficulty is low.

[0027] During assembly, first install the ball circulator 6 into the nut 9, and then screw in the assembly mandrel until the conical diversion groove 5 of the mandrel is directly opposite to the return ball groove 7 of the first ball circulator 6. At this time, the nut 9 already has circumferential support, and there is no need to worry about radial movement between the mandrel and the nut 9. Hold the mandrel by hand, and support the nut with the index finger and thumb. Use tweezers or a spoon to place the ball 8 into the conical notch 4 at the end face of the mandrel, so that the ball 8 flows into the nut 9 along the conical diversion groove 5 until a full circle is filled. It is also possible to prepare the quantity of balls 8 for a full circle in advance and put them in together. Repeat the above operation until all the nut spiral grooves corresponding to the ball circulators 6 are filled with balls 8. Then continue to rotate the mandrel to move the nut 9 to the smooth shaft 2. Finally, replace the screw with the mandrel and screw it into the nut 9.

[0028] When assembling the ball 8 of the present utility model, it is not necessary to manually control the concentricity of the mandrel and the nut 9, which reduces the assembly difficulty and labor intensity. Even without assembly experience, one can quickly get started, improving the assembly efficiency. One end of the mandrel is provided with a spiral groove 1, which can prevent the mandrel from separating from the nut 9 and causing the ball 8 to escape, and can provide guidance for the assembly of the ball 8, reducing phenomena such as misassembly and ball jamming. A conical notch 4 is provided at the end face of the spiral groove of the mandrel, which can prevent the ball 8 from scattering due to unsteady hands during assembly.

[0029] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A mandrel for ball assembly in a ball screw, comprising a mandrel body, characterized in that: A spiral groove is provided at the front end of the core shaft body, and the rear end is an optical axis. The spiral groove is divided into three sections, namely the first spiral groove section, the second spiral groove section and the third spiral groove section. The middle diameter of the first spiral groove section is between the middle diameters of the screw and the ball circulator positioning boss, the middle diameter of the second spiral groove section is a gradual middle diameter, and the middle diameter of the third spiral groove section is smaller than the middle diameter of the screw. A conical recess is provided on the end face of the spiral groove end of the core shaft body, and a conical guide groove is provided at the bottom of the conical recess.

2. The core shaft for ball assembly in a ball screw according to claim 1, characterized in that: The middle diameter of the second spiral groove section gradually changes from 0.5 mm smaller than the middle diameter of the lead screw to 0.1 mm smaller than the middle diameter of the lead screw.

3. The core shaft for ball assembly in a ball screw according to claim 2, characterized in that: The middle diameter of the third spiral groove segment is 0.1 mm smaller than the middle diameter of the lead screw.

4. The core shaft for ball assembly in a ball screw according to claim 3, characterized in that: The angle of the tapered recess is 140° to 160°.

5. The core shaft for ball assembly in a ball screw according to claim 4, characterized in that: The taper of the conical guide groove is 3° to 6°.

6. The core shaft for ball assembly in a ball screw according to claim 1 or 5, characterized in that: The diameter of the conical guide groove is 0.1 mm to 0.2 mm larger than the diameter of the ball.

7. The core shaft for ball assembly in a ball screw according to claim 6, characterized in that: The diameter of the optical axis is 0.1mm to 0.2mm smaller than the bottom diameter of the spiral groove of the lead screw.

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