TWI661143B - Outer circulation ball screw - Google Patents

Abstract

An external circulation ball screw includes a screw shaft, a nut, a cover, a return element and a plurality of rolling elements. A groove is formed on the outer surface of the nut, and two return holes are formed in the groove. The first step of the nut in the groove has a first half return path, the second step of the cover body has a second half return path, and the second half return path and the first half return path together form a return path. Alternatively, a third step with a return hole is formed in the cover body or the nut in the groove. Allows users to use reflow elements of the same size and with reflow channels of different lengths.

Description

Outer circulation ball screw

The invention relates to a ball screw, in particular to an external circulation ball screw.

General ball screws are divided into internal circulation type and external circulation type. When used under high load conditions, external circulation ball screws are mostly used. For example, the Republic of China Publication No. I509169 discloses an external circulation ball screw, which is connected to each other by the return channels of the two return elements arranged in the groove, so that the balls can circulate and the ball screw operates smoothly.

However, the aforementioned external circulation ball screw has the following problems:

1. For different length nut (different number of rolls), different size reflow element molds need to be opened in order to connect the reflow channels of each reflow element installed in the nut to each other, which will increase the production cost.

2. The reflow element is manufactured by injection molding technology, and the reflow element with increased length is more prone to component deformation. The increased time for trimming the reflow element during assembly will increase the assembly time. In addition, the deformation of the reflow element will also make the return channels of each reflow element inaccurately connected, making the ball circulation not smooth.

The main purpose of the present invention is to provide an external circulation ball screw, which uses a reflow element of the same size in the case of nuts of different lengths, thereby saving the cost of mold development.

In order to achieve the foregoing object, an external circulation ball screw provided according to the present invention includes a screw shaft and has an external thread groove. A nut is sleeved on the screw shaft so as to be movable along the axial direction of the screw shaft. The nut has an internal thread groove, and the internal thread groove of the nut and the external thread groove of the screw shaft form a load together. path. The nut forms a groove on the outer surface, and forms two return holes in the groove. Each of the return holes allows the load path to communicate with the groove. The nut forms a first step in the groove, and the first step is located between the return holes; the nut also forms a first half return channel on the first step. A cover is disposed on the nut and covers the groove. A second step is formed in the cover body, and a second half return path is formed on the second step by the cover body. The second half return path and the first half return path together form a return path. Two reflow elements, each of which has a channel inside. Each reflow element has a first end and a second end at each end of the channel. A first end of each of the return elements is inserted into a return hole of the nut, so that each of the channels communicates with the load path. The second ends of each of the return elements are located on both sides of the return path, and each of the channels communicates with the return path; the load path, the return path, and each of the channels together form a return path. The plurality of rolling elements move within the return path.

Therefore, an outer circulation ball screw of the present invention is provided with the first half return passage and the second half return passage by the nut and the cover, so that the same size return flow elements can be used with different lengths. In addition to responding to the needs of nuts of different lengths, the return channel can also save the mold cost of the return component. In addition, with the return channel, the required length of the return component can be shortened, manufacturing deformation of the return component can be reduced, and the ball screw assembly efficiency can be improved.

More preferably, the second ends of the reflow elements abut against the first or second stage, respectively. In this way, each of the reflow elements abuts against the first stage or the second stage, so that the reflow elements can be stably disposed on the nut.

In addition, each of the reflow elements can also form a positioning protrusion at the second end. The cover body is formed with a retaining wall on opposite sides of the second stage, a positioning groove is formed between each of the retaining wall and the second stage, and each of the positioning protrusions is restricted in each of the positioning grooves. Thereby, each of the reflow elements can be stably disposed on the nut.

It is also worth mentioning that the cover has an oil injection hole, and the oil injection hole communicates with the return channel. It is convenient for the user to inject lubricating oil into the cover body, and ensure that the lubricating oil directly lubricates each rolling element.

The invention also provides an external circulation ball screw, which includes a screw shaft and has an external thread groove. A nut is sleeved on the screw shaft so as to be movable along the axial direction of the screw shaft. The nut has an internal thread groove, and the internal thread groove of the nut and the external thread groove of the screw shaft form a load together. path. The nut forms a groove on the outer surface, and forms two return holes in the groove. Each of the return holes allows the load path to communicate with the groove. A cover is disposed on the nut and covers the groove. A third step is formed in the cover body or the nut in the groove, and the third step is located between the return holes, and a return path is formed on the third step. The two reflow elements each have a channel inside. Each reflow element has a first end and a second end at each end of the channel. A first end of each of the return elements is inserted into a return hole of the nut, so that each of the channels communicates with the load path. The second ends of each of the return elements are located on both sides of the return path, and each of the channels communicates with the return path; the load path, the return path, and each of the channels together form a return path. The plurality of rolling elements move within the return path.

More preferably, the second ends of the reflow elements abut against the third stage, respectively. In this way, each of the reflow elements abuts against the third stage, so that the reflow elements can be stably disposed on the nut.

In addition, each of the reflow elements can also form a positioning protrusion at the second end. The cover body is formed with a retaining wall on opposite sides of the third stage, a positioning groove is formed between each of the retaining wall and the third stage, and each of the positioning protrusions is restricted in each of the positioning grooves. Thereby, each of the reflow elements can be stably disposed on the nut.

It is also worth mentioning that the cover has an oil injection hole, and the oil injection hole communicates with the return channel. It is convenient for the user to inject lubricating oil into the cover body, and ensure that the lubricating oil directly lubricates each rolling element.

10‧‧‧External circulation ball screw

11‧‧‧Screw shaft

111‧‧‧external thread groove

12‧‧‧nut

121‧‧‧ Internal thread groove

122‧‧‧Groove

123‧‧‧Return hole

124‧‧‧first stage

125‧‧‧ the first half return

13‧‧‧ cover

131‧‧‧second stage

132‧‧‧Second Half Return Road

133‧‧‧ Retaining wall

134‧‧‧Positioning slot

135‧‧‧oil injection hole

14‧‧‧ reflow element

141‧‧‧channel

142‧‧‧ the first end

143‧‧‧ second end

144‧‧‧Positioning protrusion

15‧‧‧Roller

161‧‧‧third stage

P1‧‧‧Load path

P2‧‧‧ Return Road

P3‧‧‧Return path

Fig. 1 is a perspective view of a first embodiment of the present invention.

Fig. 2 is a partially exploded view of the first embodiment of the present invention.

Fig. 3 is an exploded view of the first embodiment of the present invention.

Figure 4 is a sectional view taken along the line 4-4 in Figure 1.

Fig. 5 is a cross-sectional view taken along line 5-5 in Fig. 1.

FIG. 6 is an exploded view of the second embodiment of the present invention, showing that the nut forms a third step in the groove.

FIG. 7 is an exploded view of the second embodiment of the present invention, showing that the third stage is formed in the cover body.

In order to explain the structure and features of the present invention in detail, the following preferred embodiments are described below with reference to the drawings.

As shown in FIGS. 1 to 5, the first preferred embodiment of the present invention provides an external circulation ball screw 10 including a screw shaft 11, a nut 12, a cover 13, two return elements 14 and a plurality of Scrolling member 15.

The screw shaft 11 has an externally threaded groove 111.

The nut 12 is sleeved on the screw shaft 11 so as to be movable along the axial direction of the screw shaft 11. The nut 12 has an internal thread groove 121, the internal thread groove 121 of the nut 12 and the screw shaft 11. The externally threaded grooves 111 collectively form a load path P1. A groove 122 is formed on the outer surface of the nut 12, and two return holes 123 are formed in the groove 122. Each of the return holes 123 allows the load path P1 to communicate with the groove 122. The nut 12 forms a first step 124 in the groove 122, and the first step 124 is located between the return holes 123. The nut 12 also forms a first half return channel 125 on the first stage 124.

The cover 13 is disposed on the nut 12 and covers the groove 122. A second stage 131 is formed in the cover 13. The cover 13 forms a second half-return passage 132 on the second stage 131. The second half-return passage 132 and the first half-return passage 125 together form a Return channel P2.

The two reflow elements 14 each have a channel 141 inside. Each of the reflow elements 14 has a first end 142 and a second end 143 at both ends of the channel 141. A first end 142 of each of the return elements 14 is inserted into a return hole 123 of the nut 12, so that each of the channels 141 communicates with the load path P1. The second ends 143 of each of the return elements 14 are located on both sides of the return path P2, and each of the channels 141 communicates with the return path P2. The load path P1, the return path P2, and each of the channels 141 form a return path P3 together.

The plurality of rolling elements 15 are moved in the return path P3.

With the above-mentioned structure, in the case where the length of the nut 12 is different for the outer-circulating ball screw 10 of the present invention, the return element 14 of the same size can still be used. By using the reflow element 14 of the same size and the reflow channels P2 of different lengths, the effect of 15 cycles of the rolling elements can be achieved. Because only a single-size reflow element 14 mold is required, and no different-size mold is required, mold costs are saved. In addition, by adopting the return flow path P2, the length of the return flow element 14 can be shortened, the deformation caused by the production of the return flow element 14 can be reduced, and the ball screw assembly efficiency can be improved.

It is worth mentioning that, in this embodiment, the second ends 143 of the reflow elements 14 abut against the first stage 124 or the second stage 131, respectively. In this way, the reflow element 14 can be stably provided on the nut 12. In addition, each of the reflow elements 14 can also form a positioning protrusion 144 at the second end 143. A blocking wall 133 is formed on the cover 13 on opposite sides of the second step 131, a positioning groove 134 is formed between each of the blocking wall 133 and the second step 131, and each of the positioning protrusions 144 is restricted to Each of the positioning grooves 134 is inside. Thereby, each of the return elements 14 can be stably provided on the nut 12.

It should also be noted that although this embodiment has the technical features of the previous paragraph, if you choose not to use the technical features of the previous paragraph, you can still achieve the use of reflow elements 14 of the same size in the case of nuts 12 of different lengths, saving Mold development costs. For example, the second ends 143 of the aforementioned reflow elements 14 abut against the first step 124 or the second step 131, respectively, or a positioning groove 134 and a positioning protrusion 144 are provided. Alternatively, the second end 143 can be separated from the first stage 124 or the second stage 131, or the setting groove 134 and the positioning protrusion 144 are not added, as long as the rolling member 15 is prevented from leaving the return path P3 from between the channel 141 and the return path P2. , Can still maintain the function of the scroll 15 cycle.

In addition, in this embodiment, the cover body 13 may also be selected to have an oil injection hole 135, and the oil injection hole 135 communicates with the return passage P2. It is convenient for a user to inject lubricating oil into the cover 13 and ensure that the lubricating oil directly lubricates each of the rolling elements 15.

As shown in FIG. 6 to FIG. 7, the second preferred embodiment of the present invention is described next. An external circulation ball screw 10 is provided. The cap 12 forms a third step 161 in the groove 122. The third step 161 is located between the reflow holes 123, and a reflow path P2 is formed on the third step 161.

In this embodiment, the second ends 143 of the reflow elements 14 abut against the third stage 161 respectively. In this way, the reflow element 14 can be stably provided on the nut 12. In addition, each of the reflow elements 14 can also form a positioning protrusion 144 at the second end 143. A blocking wall 133 is formed on the cover 13 on opposite sides of the third step 161, a positioning groove 134 is formed between each of the blocking wall 133 and the third step 161, and each of the positioning protrusions 144 is restricted to Each of the positioning grooves 134 is inside. Thereby, each of the return elements 14 can be stably provided on the nut 12.

However, if you choose not to use the technical features described in the previous paragraph, you can still achieve the effect of saving the cost of mold development by using the same size reflow element 14 in the case of nuts 12 of different lengths.

In addition, in this embodiment, the cover body 13 may also be selected to have an oil injection hole 135, and the oil injection hole 135 communicates with the return passage P2. It is convenient for a user to inject lubricating oil into the cover 13 and ensure that the lubricating oil directly lubricates each of the rolling elements 15.

Claims (8)

An external circulation ball screw comprises: a screw shaft having an externally threaded groove; a nut cap sleeved on the screw shaft movably along the axial direction of the screw shaft; the nut has an internal thread groove, The internally threaded groove of the nut and the externally threaded groove of the screw shaft together form a load path; the nut forms a groove on the outer surface, and two return holes are formed in the groove, and each of the return holes allows the load The path communicates with the groove; the nut forms a first step in the groove, and the first step is located between the return holes; the nut also forms a first half return channel on the first step; A cover body is provided on the nut and covers the groove; a second stage is formed in the cover body, and the cover body forms a second half-return passage on the second stage, the second half-return passage and the The first half of the return channels together form a return channel; two return components, each of which has a channel inside; each return component has a first end and a second end at each end of the channel; each return The first end of the component is inserted into the return hole of the nut to allow each of the channels to communicate with the load The second end of each return element is located on both sides of the return path, and each of the channels communicates with the return path; the load path, the return path, and each of the channels together form a return path; The system moves in this return path. An external circulation ball screw according to item 1 of the scope of the patent application, wherein the second ends of the return elements abut against the first or second stage, respectively. An external circulation ball screw according to item 1 of the scope of the patent application, wherein: each of the return elements forms a positioning protrusion at the second end; and the cover body forms one on the opposite side of the second step. A retaining wall, a positioning groove is formed between each of the retaining walls and the second stage, and each of the positioning protrusions is restricted in each of the positioning grooves. An external circulation ball screw according to item 1 of the scope of the patent application, wherein the cover has an oil injection hole, and the oil injection hole communicates with the return channel. An external circulation ball screw comprises: a screw shaft having an externally threaded groove; a nut cap sleeved on the screw shaft movably along the axial direction of the screw shaft; the nut has an internal thread groove, The internally threaded groove of the nut and the externally threaded groove of the screw shaft together form a load path; the nut forms a groove on the outer surface, and two return holes are formed in the groove, and each of the return holes allows the load A path communicates with the groove; a cover body is provided in the nut and covers the groove; a third stage is formed in the cover body or the nut in the groove, and the third stage is located in each of the reflows Between the holes, and a return channel is formed on the third stage; two return elements each have a channel inside; each of the return elements has a first end and a second end at each end of the channel; The first end of the return element is inserted into the return hole of the nut to allow each channel to communicate with the load path; the second end of each return element is located on both sides of the return channel, and each channel communicates with the return channel; The load path, the return channel and each of the channels together form a A return path; and a plurality of rolling elements moving within the return path. An external circulation ball screw according to item 5 of the scope of patent application, wherein the second ends of the return elements abut against the third stage, respectively. An external circulation ball screw according to item 5 of the scope of the patent application, wherein: each of the return elements forms a positioning convex part on the second end; and the cover body forms one on the opposite sides of the third step. A retaining wall, a positioning groove is formed between each of the retaining walls and the third step, and each of the positioning protrusions is restricted in each of the positioning grooves. An external circulation ball screw according to item 5 of the scope of the patent application, wherein the cover has an oil injection hole, and the oil injection hole communicates with the return channel.