Description

BEARING SCREW TRANSFERRING DEVICE

Technical Field

[1] The present invention relates to a screw transferring(or conveying) device using bearings, and more particularly, to a screw transferring device that has a plurality of radial bearings adapted to come into contact with the lateral surfaces and edges of a plurality of screw threads of a screw shaft in such a manner as to be rotated at a fixed position along a spiral passageway formed on the inner peripheral surface of a nut body, and alternatively, has a plurality of radial bearings adapted to come into contact with the top surface edges of the screw threads of the screw shaft in such a manner as to be rotated at a fixed position along the spiral passageway of the nut body, such that even when the screw shaft is moved at a substantially high speed, the noise generated during the movement can be greatly reduced, while the supporting force exerted in the axial direction of the screw shaft is being improved.

[2]

Background Art

[3] A typical ball screw transferring(or conveying) device is configured such that a plurality of balls is rolled between a ball nut and a screw shaft to conduct linear movements. FIG.l shows a conventional deflector type ball screw transferring device using balls, which is provided with a return piece 18 so that balls 10 circulate. Further, spiral valleys 12 are formed along the long outer circumferential surface of the screw shaft.

[4] Further, a ball nut 13 is disposed along the outer periphery of the screw shaft 11, having the outer shape of a hollow cylindrical pipe and sprial inner grooves 14 formed along the inner circumferential surface thereof so as to face the spiral valleys 12 of the screw shaft 11. The plurality of steel balls 10 are inserted between the spiral valleys 12 and the inner grooves 14, which are arranged to face each other and each have a semicircular cross-section. The return piece 18 is formed at a predetermined position in the ball nut 13 so as to circulate the balls 10.

[5] Thus, the ball screw transferring device is constructed such that when an external rotating force is transmitted to the screw shaft 11 to rotate the screw shaft 11, the balls 10 inside the ball nut 13 roll along the valleys 12 and the inner grooves 12 and 14, thereby pushing a nut body or a moving block fixed thereto in the axial direction of the screw shaft 11, and next, the balls 10 circulate through the return piece 18 again.

[6] However, the conventional ball screw transferring device has some problems in that it does not have a unit for attenuating vibration and noise generated when the balls 10

disposed between the ball nut 13 and the screw shaft 11 roll, so that noise is transmitted without being attenuated and durability is reduced due to vibrations. [7]

Disclosure of Invention

Technical Problem

[8] Accordingly, the present invention has been made to solve the above problems occurring in the prior arts, and it is an object of the present invention to provide a bearing screw transferring(or conveying) device that has a plurality of radial bearings adapted to come into contact with the lateral surfaces and edges of a plurality of screw threads of a screw shaft, and alternatively, has a plurality of radial bearings adapted to come into contact with the top surface edges of the screw threads of the screw shaft, such that when the screw shaft is moved at a substantially high speed, the noise generated during the movement can be greatly reduced, while the supporting force exerted in the axial direction of the screw shaft is being improved.

[9]

Technical Solution

[10] To achieve the above object, according to the present invention, there is provided a bearing screw transferring device including: a screw shaft having a plurality of spiral screw threads formed along the outer circumferential surface thereof and a plurality of spiral valleys formed between the spiral screw threads; a nut body screw-coupled to the screw shaft and having a cylindrical shape having a spiral passageway formed along the inner circumferential surface thereof so as to mate with the screw threads of the screw shaft; and a plurality of radial bearings rotatably mounted at fixed positions along the spiral passageway of the nut body.

Advantageous Effects

[11] According to the of the present invention, there is provided a bearing screw transferring device that has a plurality of radial bearings adapted to come into contact with the lateral surfaces and edges of a plurality of screw threads of the screw shaft, and alternatively, adapted to come into contact with the top surface edges of the screw threads of the screw shaft, such that when the screw shaft is moved at a substantially high speed, the noise generated during the movement can be greatly reduced, while the supporting force exerted in the axial direction of the screw shaft is being improved.

[12]

Brief Description of the Drawings

[13] FIG.1 is a sectional view showing a structure of a general ball screw.

[14] FIG.2 is a horizontal sectional view showing the general ball screw of FIG.1.

[15] FIG.3 is a perspective view showing a structure of a bearing screw transferring

device according to one preferred embodiment of the present invention. [16] FIG.4 is a vertical sectional view showing the structure of the bearing screw transferring device according to the preferred embodiment of the present invention. [17] FIG.5 is a sectional view showing a radial bearing coming into contact with a screw thread in the bearing screw transferring device of the present invention. [18] FIG.6 is a sectional view showing the radial bearing coming into contact between the screw threads in the bearing screw transferring device of the present invention. [19] FIG.7 is a sectional view showing the radial bearing coming into contact with the edge of the screw thread in the bearing screw transferring device of the present invention. [20] FIG.8 is a view showing the operating state of the bearing screw transferring device of FIG.3. [21] FIGS.9 to 13 are sectional views showing a bearing screw transferring device according to another preferred embodiment of the present invention. [22] FIG.14 is a sectional view showing a bearing screw transferring device according to still another preferred embodiment of the present invention.

[23] FIGS.15 and 16 are sectional views showing the shapes of the spring in FIG.14.

[24] FIG.17 is a perspective view showing a bearing screw transferring device according to yet another preferred embodiment of the present invention. [25] FIG.18 is a horizontal sectional view showing the bearing screw transferring device of FIG.18. [26] FIGS.19 and 20 are sectional views showing the radial bearing coming into contact with the screw thread in the bearing screw transferring device of FIG.17. [27] FIG.21 is a view showing the operating state of the bearing screw transferring device of FIG.17.

[28] *Explanations on the reference numerals of the main parts in the drawings*

[29] 100: screw shaft 110: valley

[30] 112: screw thread 112a: lateral surface

[31] 112b: edge 200: radial bearing

[32] 300: nut body 310: installing hole

[33] 320: lubricant oil supply hole

[34] 600: bearing-rotating shaft

[35] 700: shaft-fixing nut

[36]

Mode for the Invention [37] Hereinafter, an explanation on a bearing screw transferring device according to preferred embodiments of the present invention will be given with reference to the

attached drawings. FIGS.3 and 4 are a perspective view and a vertical sectional view showing a structure of a bearing screw transferring device according to one preferred embodiment of the present invention. As shown in FIG.5, the bearing screw transferring device according to one preferred embodiment of the present invention includes a screw shaft 100 having a plurality of spiral valleys 110 formed along the outer circumferential surface thereof and a radial bearing 200 adapted to come into contact with the lateral surface 112a and edge of each of a plurality of screw threads 112 of the screw shaft 100 in such a manner as to be rotated at a fixed position along a spiral passageway formed on the inner peripheral surface of a nut body 300, and alternatively, has the radial bearing 200 adapted to come into contact with the edge of each of the spiral valleys 110 of the screw shaft 100 in such a manner as to be rotated at a fixed position along the spiral passageway of the nut body 300, such that the radial bearing 200 is rotated along the outer circumferential surfaces of the screw threads 112. The outer race of the radial bearing 200 is moved to the both sides thereof along the lateral surfaces 112a of the screw threads 112 of the screw shaft 100 or along the edge surfaces 112b between the lateral surfaces and the top surfaces of the screw threads 112 of the screw shaft 100.

[38] In the meanwhile, the nut body 300 itself may be used as a moving block, but as shown in FIG.13, a flange may be formed on the nut body 300 in such a way of being coupled to a moving block by means of coupling means.

[39] Referring in detail to the installing structure of the radial bearing 200, as shown in

FIG.4, the radial bearing 200 is rotatably mounted by means of a bearing-rotating shaft 600 and a shaft- fixing nut 700 mounted to be passed through an installing hole 310 formed on the nut body 300, and an oil supply through-hole 320 is formed on a predetermined portion of the nut body 300.

[40] On the other hand, when the cross-section of each of the screw threads 112 forming a spiral of the screw 100 has a triangular, rectangular, or trapezoidal shape, the radial bearing 200 is mounted between the screw threads 112. At this time, the radial bearing 200 is mounted to come into contact with the lateral surface 112a of each screw thread 112, and preferably, the radial bearing 200 is mounted in such a way that the outer race thereof completely comes into contact with the lateral surface 112a. Thus, each installing hole 310 is formed horizontally with respect to the contact surface with the surface of each screw thread 112 with which the outer race of the radial bearing 200 comes into contact.

[41] Preferably, the radial bearing 200 is a radial ball bearing or a radial needle roller bearing. The shape of each screw thread 112 of the screw shaft 100 is described herein. However, the shape of each screw thread 112 of the screw shat 100 may be easily changed, and it is not limited to this embodiment.

[42] Moreover, as shown in FIGS.6 and 7, the radial bearing 200 may be inserted between the screw threads 112 in such a way of coming into contact therebetween, and alternatively, the radial bearing 200 may come into contact with the edge of the screw thread 112. At this time, it is preferable as noted above that the rolling surface of the outer race of the radial bearing 200 fully comes into contact with the lateral surface 112a of the screw thread 112.

[43] Further, as shown in FIG.20, the radial bearing 200 may come into contact with the edge of the top surface of each screw thread 110 formed on the outer circumferencial surface of the screw shaft 100. At this time, it is preferable that the bearing-rotating shaft is placed in parallel to the contact surface with the edge of the top surface of each screw thread 110 at the contact point between the rolling surface of the outer race of the radial bearing 200 and the edge of the top surface of each screw thread 110.

[44] Thus, the installing hole 310 is formed horizontally with respect to the contact surface with the surface of each screw thread 112 with which the outer race of the radial bearing 200 comes into contact.

[45] On the other hand, the nut body 300 may have the lubricant oil supply hole 320 adapted to supply oil to the inside thereof, and as shown in FIGS.10 and 11, pressurizing means 900 may be further disposed so as to pressurize the radial bearing 200 mounted to the bearing-rotating shaft 600 toward the screw thread 112.

[46] Further, as shown in FIG.12, cooling means 1000 may be further disposed at the outside of the nut body 300 so as to rapidly cool the nut body 300 when the nut body 300 is overheated. The cooling means 1000 supplies refrigerants through a pipe passageway (not shown) communicating with the installing hole 310.

[47] Under the above-mentioned structure, as shown in FIG.8, if the screw shaft 100 is rotated, the radial bearing 200 that is insertedly mounted between the spiral valleys 110 of the screw shaft 100, is guided and moved along the outer surfaces of the screw threads 112, and at this time, the plurality of radial bearings 200 are mounted at regular inervals at the inside of the nut body 300 along the central lines of the spiral valleys 110, thereby providing higher stability and allowing the entire nut body 300 to be easily moved.

[48] Meanwhile, when a load is applied to the screw threads 112 during the rotation of the screw shaft 100, the radial bearings 200 contact the metallic surfaces of the spiral valleys 110. At this time, the load is transmitted perpendicularily to the rolling surfaces of the radial bearings 200 by means of the lateral surfaces 112a of the screw threads 112, thereby increasing the stress to allow the supporting force against the radial bearings 200 to be improved.

[49] On the other hand, if the radial bearings 200 are larger than the spiral valleys 110 of the screw shaft 100, the supporting force against the radial bearings 200 can be more

improved, and further, the life period of the radial bearings 200 can be prolonged.

[50] On the other hand, as shown in FIG.4, if the bearing-rotating shaft 600 is passed through the installing hole 310 of the nut body 300 in such a manner as to be protruded toward the inside of the nut body 300, a bushing 800 may be further disposed so as to prevent the bearing-rotating shaft 600 from being moved, and further, as shown in FIG.9, the radial bearing 200 may be fitted partially to the nut body 300.

[51] As shown in FIGS.10 and 11, the pressurizing means 900 may be further provided so as to pressurize the radial bearing 200 mounted to the bearing-rotating shaft 600 toward the screw thread 112, thereby removing the gap between the nut body 300 and the radial bearing 200. At this time, the pressurizing means 900 is configured having a through-hole formed on the nut body 300 and having a screw mounted to the inside thereof and a pin member composed of a fastening bolt and a pressurizing rod screw- coupled to the through-hole. Alternatively, the fastening bolt and the pressurizing rod are separable from each other, and a spring is placed beween the fastening bolt and the pressurizing rod.

[52] On the other hand, FIG.14 is a sectional view showing a bearing screw transferring device according to still another preferred embodiment of the present invention, wherein a spring 2000 is further disposed between the installing hole 310 of the nut body 300 and the bearing-rotating shaft 600. The spring 2000 is a plate spring that is depressed inwardly at the center portion thereof, as shown in FIG.15, and alternatively, it is protruded outwardly at the center portion thereof, as shown in FIG.16.

[53] The installation of the spring 2000 allows the mechanical error generated by lead errors to be corrected so as to reliably maintain the close contact between the radial bearing 200 and the screw thread 112 and further prevents the mechanical destruction according to the noise absorption and impact application so as to extend the life period of the device.

[54] FIG.17 is a perspective view showing a bearing screw transferring device according to yet another preferred embodiment of the present invention, and FIG.18 is a horizontal sectional view showing the bearing screw transferring device of FIG.18. Referring to FIGS.17 and 18, the bearing screw transferring device according to the present invention is provided with the screw shaft 100 having spiral concaved valleys 110 and rounded edge portions 112b on which the concaved valleys 110 meet the top surfaces of the screw shaft so as to form curved lines thereon. Each of the rounded edge portions 112b is inserted into a concaved portion 210 formed along the outer race of the radial bearing 200, such that the radial bearing 200 runs along the edge portions 112b of the screw shaft 100.

[55] The rotary shaft of the radial bearing 200 is preferably at a right angle with respect to the contacting surface with each edge portion 112b at the contact point between the

rolling surface of the radial bearing 200 and each edge portion 112b.

[56] As shown in FIG.20, the rolling surface of the radial bearing 200 is flat, and the edge portion of the screw shaft 100 is rounded. However, as shown in FIG.19, if the edge portion is rounded, the rolling surface of the radial bearing is formed concaved along the center portion thereof, which desirably ensures the stability of the operation of the radial bearing 200.

[57] As shown in FIG.19 or FIG.20, if the screw shaft 100 is rotated, the radial bearing

200 runs along the edge portions 112b of the screw shaft 100, and at this time, the plurality of radial bearings 200 are mounted at regular intervals at the inside of the nut body 300 along the central lines of the edge portions 112b, thereby providing higher stability and allowing the entire nut body 300 to be easily moved.

[58] Meanwhile, when a load is applied to the screw threads 112 during the rotation of the screw shaft 100, the concaved portions of the radial bearings 200 contact the metallic surfaces of the edge portions 112b of the screw shaft 100. At this time, the load is transmitted perpendicularily to the radial bearings 200, thereby increasing the stress to allow the supporting force against the radial bearings 200 to be improved.

[59] On the other hand, if the edge portions 112b of the screw shaft 100 are inserted into and contacted with the concaved portions 210 of the radial bearings 200, the contacted area between the radial bearings 200 and the screw shaft 100 becomes large, thereby improving the supporting force against the radial bearings 200, and further extending the life period of the radial bearings 200.

[60]