Rotary Table Device

Abstract

To provide a rotary table device capable of improving drive efficiency and durability. [Solution] The rotary table device (1) comprises a rotary table device main body (10), a rotary table (12) rotatably supported on the main body (10) via a table main shaft (12a), a turret (13) fixed to the table main shaft (12a), a plurality of rolling support members (14) fixed to the turret (13), a camshaft (20) having cam ribs (21) formed on its outer periphery that come into rolling contact with the rolling support members (14), and a pair of support members (30, 35) arranged on the opposite side of the table main shaft (12a) from the camshaft (20) and supporting both ends of the cam ribs (21) on the camshaft (20) toward the table main shaft (12a).

Description

[Technical Field]

[0001] The present invention relates to a rotary table device. [Background technology]

[0002] Rotary table devices have been widely used in processing machines, assembly machines, and the like as mechanisms for indexing and rotating a table by a predetermined angle. One known example of such a rotary table device is one that uses a worm gear mechanism to transmit rotation. A worm gear mechanism is configured to transmit the rotation of a worm screw to a worm wheel at a reduced speed, and has the advantages of being able to control the movement speed between two indexing points on the rotary table and being able to perform arbitrary positioning regardless of the number of indexes.

[0003] For example, Patent Document 1 (JP 2010-125544 A) discloses a rotary table device equipped with a worm gear mechanism. Patent Document 1 discloses that a worm wheel fixed to the rotary table main shaft engages with a worm screw formed on the worm shaft, and rotation of the worm shaft rotates the worm wheel, which in turn rotates the rotary table. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-125544 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a worm gear mechanism, the tooth surfaces of the worm screw and the worm wheel are in sliding contact with each other, which can easily cause wear, and the tooth surfaces can wear out over long periods of use.Furthermore, loss occurs due to sliding friction, which can result in poor drive efficiency.

[0006] The present invention has been made to solve the above-mentioned problems, and its object is to provide a rotary table device that can improve drive efficiency and suppress wear to increase durability. [Means for solving the problem]

[0007] For this purpose, a rotary table device according to one aspect of the present invention comprises a rotary table device main body, a rotary table rotatably supported on the rotary table device main body via a table spindle, a turret fixed to the table spindle, a plurality of rolling support members fixed to the turret, a camshaft having cam ribs formed on its outer periphery that come into rolling contact with the rolling support members, and a pair of support members that are arranged on the opposite side of the table spindle from the camshaft and support both ends of the cam ribs on the camshaft toward the table spindle.

[0008] Preferably, the support member includes a fixed member fixed to the rotary table device main body, and a roller rotatably supported by the fixed member, the outer circumferential surface of which contacts the camshaft.

[0009] Preferably, the cam ribs are formed so that the rib thickness decreases from one side to the other in the rotational direction of the camshaft, and the rollers arranged on the side with the thinner rib thickness are formed thicker than the rollers arranged on the side with the thicker rib thickness, providing stronger support.

[0010] Preferably, the rollers are disposed at opposite ends of the cam rib in the circumferential direction, spaced apart from each other.

[0011] Preferably, the rotary table device main body includes a lid for attaching the support member facing the camshaft, and a shim is interposed between the lid and the support member.

[0012] Preferably, the fixed member has an elastic member that elastically supports the load from the roller. [Effects of the Invention]

[0013] According to the rotary table device of the present invention, it is possible to improve drive efficiency and durability. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view showing a rotary table device according to a first embodiment of the present invention. [Figure 2] 1 is a schematic vertical cross-sectional view showing a rotary table device according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a partially enlarged view of FIG. [Figure 4] FIG. 3 is a partially enlarged view of FIG. 2. [Figure 5] 10 is a graph showing the indexing accuracy of the rotary table device. [Figure 6] 1A and 1B are schematic diagrams for explaining the state of a camshaft when an unbalancing load is applied, in which (A) shows the rotary table device of the first embodiment, and (B) shows a conventional rotary table device. [Figure 7] FIG. 10 is a partially enlarged view of a rotary table device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which like reference numerals denote like or corresponding parts and will not be described repeatedly.

[0016] <First Embodiment> Fig. 1 is a schematic cross-sectional view showing a rotary table device according to a first embodiment of the present invention, and Fig. 3 is a partially enlarged view thereof. Fig. 2 is a schematic vertical cross-sectional view showing a rotary table device according to a first embodiment of the present invention, and Fig. 4 is a partially enlarged view thereof. The rotary table device 1 will be outlined with reference to Figs. 1 to 4.

[0017] As shown in Figure 1, the rotary table device 1 generally comprises a rotary table device main body 10 and a rotary table 12 rotatably supported on the rotary table device main body 10 via a table main shaft 12a. The rotary table device main body 10 and the rotary table 12 are the main elements of the rotary table device 1 and are formed, for example, from a rigid body. In the case of a rotary table device 1 equipped with an indexing mechanism, it is possible to index and rotate the rotary table 12 by a predetermined angle. This will be explained in detail below.

[0018] The rotary table device main body 10 is a non-rotating part. In the following description, the rotary table device main body 10 will be simply referred to as the main body 10. As shown in particular in Figures 1 and 3, the main body 10 has a lid 11 for attaching support members 30, 35 facing the camshaft 20. The support members 30, 35 will be described later. A shim 40 is interposed between the main body 10 and the lid 11.

[0019] The rotary table 12 is integrally connected to one end of a table spindle 12a provided inside the rotary table device 1. The rotary table 12 is supported rotatably around the table spindle 12a. A turret 13 is fixed to the table spindle 12a. The turret 13 is provided on the back (bottom) of the rotary table 12, and multiple rolling support members 14 are fixed at regular intervals in the circumferential direction to the turret 13. The multiple rolling support members 14 are arranged on the outer periphery of the rotary table 12. The multiple rolling support members 14 are typically configured as cam followers. The cam follower 14 includes a shaft portion and a roller portion rotatably supported on the outer periphery of the shaft portion, and the roller portion comes into rolling contact with a cam rib 21 of a camshaft 20 (described later). As a result, the rotary table 12 is rotatably supported relative to the main body 10 and rotates integrally with the multiple cam followers 14.

[0020] Cam ribs 21 that come into rolling contact with cam followers 14 are formed on the outer periphery of camshaft 20. Cam rib 21 is located in the axial center of camshaft 20. Cam rib 21 is formed so that the rib thickness gradually decreases from one side to the other in the rotational direction of camshaft 20. The rib thickness here refers to the crest width of the threads formed on cam rib 21, and is configured so that the crest width changes along the rotational direction of camshaft 20. As shown in FIG. 3, if the rib thickness on one side of cam rib 21 in the rotational direction is T1 and the rib thickness on the other side is T2, then a relationship of T1 > T2 is established, and it can be seen that the rib thickness decreases from one side to the other in the rotational direction.

[0021] In this way, by varying the rib thickness of the cam rib 21 along the direction of rotation, the contact state with the cam follower 14 changes smoothly, and the load is transmitted evenly. As a result, impact and wear during meshing can be suppressed, and quietness and durability can be improved.

[0022] The camshaft 20 extends in the tangential direction of the cam follower 14, and both ends thereof are rotatably supported by a pair of rolling bearings 19, 19 that serve as camshaft bearings. The inner rings of the rolling bearings 19, 19 are fitted and fixed to the outer periphery of the camshaft 20. The outer rings of the rolling bearings 19, 19 are fixed to bearing blocks 18, 18 attached inside the rotary table device 1.

[0023] In this embodiment, the bearing block 18 on the right side of the drawing is double-row and is provided with two rolling bearings 19, while the bearing block 18 on the left side of the drawing is provided with one rolling bearing 19. This allows the axial force applied from the cam follower 14 to the camshaft 20 to be appropriately received.

[0024] A gear 17 fixed to one end of the camshaft 20 is in rolling contact with a gear 16 coupled to a motor shaft 15 of the drive motor. The drive motor rotates the rotary table 12 and is controlled by an indexing control device (not shown).

[0025] A pair of support members 30, 35 are provided on both ends of the cam rib 21 to support both ends of the cam rib 21 toward the table spindle 12a. The pair of support members 30, 35 are arranged on the opposite side of the camshaft 20 from the table spindle 12a. The first support member 30 located on the right side of the drawing supports the camshaft 20 on the right side of the end of the cam rib 21 toward the table spindle 12a. The second support member 35 located on the left side of the drawing supports the camshaft 20 on the left side of the end of the cam rib 21 toward the table spindle 12a. Of these paired support members 30, 35, the first support member 30 is arranged adjacent to one end of the cam rib 21, and the second support member 35 is arranged adjacent to the other end of the cam rib 21.

[0026] The pair of support members 30, 35 are fixed to the inner sides of bearing blocks 18, 18 included in the rotary table apparatus 1. As shown in FIG. 3, the support members 30, 35 include fixed members 31, 36 fixed to the main body 10, and rollers 32, 37 rotatably supported by the fixed members 31, 36 and whose outer circumferential surfaces contact the camshaft 20. The fixed members 31, 36 function as bases that fix the support members 30, 35 to the main body 10, and their bottom surfaces may be exposed to the outside. As shown in FIG. 4, the first support member 30 includes two first rollers 32, 32. Although not shown, the second support member 35 includes two second rollers 37, 37, similar to the first support member 30.

[0027] 4, a pair of first rollers 32, 32 attached to the first support member 30 has a rotation axis parallel to the camshaft 20 and contacts the adjacent outer peripheral portion 24 of the camshaft 20 adjacent to the axial end of the cam rib 21. Specifically, the pair of first rollers 32, 32 are arranged spaced apart from each other at both ends of the camshaft 20 in the circumferential direction.

[0028] The first roller 32 is rotatably supported by a rolling bearing on the fixed member 31 of the support member 30, and when the camshaft 20 is bent, the first roller 32 comes into contact with the adjacent outer peripheral portion 24 of the camshaft 20 and is rotated by the camshaft 20. The rolling bearing of the first roller 32 may take the form of a roller bearing, for example, or both axial ends of the first roller 32 are rotatably supported by the fixed member 31. The second support member 35 has the same configuration as described above.

[0029] As shown in Fig. 3, the first roller 32 and the second roller 37 have different thicknesses. The first roller 32, which is located on the thinner rib side of the cam rib 21 (rib thickness: T1), is formed thicker than the second roller 37, which is located on the thicker rib side (rib thickness: T2). Specifically, the thickness T3 of the first roller 32 is thicker than the thickness T4 of the second roller 37 (T3 > T4). Typically, the thickness T3 of the first roller 32 is 1.25 times the thickness T4 of the second roller 37, but it is preferably 1.05 to 1.5 times.

[0030] Fig. 5 is a graph showing the indexing accuracy at 18° intervals when the rotary table device 1 is rotated 360° in the forward direction. In Fig. 5, the gray line shows the indexing accuracy of a rotary table device that does not have support members 30, 35, and the black line shows the indexing accuracy of a rotary table device 1 that has support members 30, 35 described in this embodiment. The vertical axis shows torque (N m), the horizontal axis (1 to 20) shows the numbers individually assigned to the 20 cam followers, and the other horizontal axis (0 to 360°) shows the arrangement angle of each cam follower 14.

[0031] As can be seen from Figure 5, the rotary table device 1 provided with the support members 30, 35 (black line) has less fluctuation in indexing accuracy than the device without the support members 30, 35 (gray line). The black line fluctuates in parts (the line's trajectory is jagged) because the support members 30, 35 are positioned at a boundary position where they may or may not come into contact with the camshaft 20. This indicates that the support members 30, 35 support the camshaft 20 only when the camshaft 20 bends slightly toward the support members 30, 35 as the rotary table 12 rotates. This result shows that providing the support members 30, 35 effectively suppresses bending of the camshaft 20 and improves the indexing accuracy of the entire rotary table device 1.

[0032] Returning to the explanation of the configuration of the rotary table device 1, as shown in FIGS. 3 and 4, a shim 40 is interposed between the main body 10 and the lid 11. The shim 40 is a thin spacer member that is arranged so as to be sandwiched between the main body 10 and the lid 11 when the support members 30, 35 are attached to the main body 10. The shim 40 is provided as a single common piece that straddles the pair of support members 30, 35. As described above, it is preferable that the support members 30, 35 are not always in contact with the camshaft 20, but are only in contact when the camshaft 20 is bent. The shim 40 is used to adjust the positional relationship between the support members 30, 35 and the camshaft 20.

[0033] By changing the thickness of the shim 40, the mounting position of the cover portion 11 changes slightly, and as a result, the position of the support member 30 supported by the cover portion 11 can be adjusted with high precision relative to the camshaft 20. In other words, by appropriately selecting the thickness of the shim 40, the positional relationship between the support member 30 and the camshaft 20 can be adjusted with high precision.

[0034] (About the condition of the camshaft when an unbalancing load is applied) The state of the camshaft when an unbalancing load is applied will be described with reference to Figures 1, 4, 6(A), and 6(B). As shown in Figure 1, when the rotary table device 1 rotates the rotary table 12 at a predetermined index angle, gear 16 is rotated by motor shaft 15 of the drive motor controlled by the control device, which rotates gear 17, causing camshaft 20 to rotate at a predetermined angle, and when this rotation is transmitted from cam rib 21 to cam follower 14, it is decelerated at a large reduction ratio, causing the rotary table 12 to rotate at the predetermined index angle.

[0035] Fig. 6(B) shows an example of a barrel cam mechanism in which support members 30, 35 are not provided. As shown in Fig. 6(B), when a workpiece W is fixed at an eccentric position on the rotary table 12 and the rotary table 12 is rotated, the cam rib 21 and the cam follower 14 come into rolling contact, and the cam shaft 20 having the cam rib 21 is subjected to an axial force and a force perpendicular to the axis from the cam follower 14. As a result, the axial center portion of the camshaft 20 where the cam rib 21 is formed tends to displace in a direction away from the cam follower 14. This tendency is more pronounced where the rib thickness is thinner.

[0036] 4 and 6(A), the first roller 32 of the first support member 30, which is disposed on the thinner rib side (T1) of the cam rib 21, is formed thicker than the second roller 37 of the second support member 35, which is disposed on the thicker rib side (T2) (T3>T4). This prevents the camshaft 20 from being deformed even when the workpiece W is fixed at an eccentric position, as shown in this embodiment of FIG.

[0037] The rotary table device 1 of this embodiment is not a worm gear mechanism made up of a worm screw and worm wheel, but is configured with a barrel cam mechanism made up of a plurality of rolling support members 14 and cam ribs 21, and is provided with a pair of support members 30, 35 that are arranged on the outer side of the camshaft 20 and support both ends of the cam rib 21 toward the rolling support members 14. This brings the cam followers 14 into rolling contact with the cam ribs 21, thereby improving drive efficiency and suppressing wear to increase durability.

[0038] Furthermore, since the support members 30, 35 support the camshaft 20 toward the table spindle 12a, it is possible to prevent the camshaft 20 from being deflected by a force perpendicular to the axis, thereby improving the rigidity and rotation transmission efficiency of the barrel cam mechanism.

[0039] Each support member 30, 35 has a pair of rollers 32, 37 that are arranged spaced apart from each other at both circumferential ends of the camshaft 20 and whose outer circumferential surfaces contact the adjacent outer circumferential portion 24 of the camshaft 20, so that the pair of rollers 32, 37 that are arranged spaced apart from each other in the circumferential direction of the camshaft 20 at the same position in the axial direction of the camshaft 20 contact the outer circumferential surface of the camshaft 20. This makes it possible to provide two rollers symmetrically, making it possible to suitably withstand the force applied to the camshaft 20 in the axis-perpendicular direction from the cam follower 14. Therefore, the force applied to the camshaft 20 in the axis-perpendicular direction can be suitably withstood between the pair of rollers 32, 37.

[0040] (Regarding the second embodiment) 7, a modified example of the support member 30A of the rotary table device 1A according to the second embodiment will be described. In the above embodiment, the support member 30 is fixedly supported by the main body 10 and the lid 11, but the present invention is not limited to this.

[0041] In this embodiment, a spring 33A is provided on a fixing member 31A that fixes a support member 30A to the lid portion 11. The spring 33A is typically a coil spring, but may be formed of an elastic member such as a leaf spring or rubber. The spring 33A elastically holds the support member 30A relative to the lid portion 11.

[0042] The spring 33A of the fixing member 31A is elastically deformable relative to the lid 11 of the main body 10. Therefore, the support member 30A is held in a state in which it is elastically pressed against the lid 11. The roller 32 attached to the support member 30A is also held so as to be pressed against the camshaft 20 by its elastic force. In other words, the spring 33A biases the roller 32 toward the adjacent outer periphery 24 of the camshaft 20. Therefore, the camshaft 20 is also elastically supported via the elastic force of the spring 33A, and the roller 32 comes into contact with the adjacent outer periphery 24.

[0043] As a result, even if the camshaft 20 bends during rotation or if the positional relationship between the components changes due to assembly errors, thermal expansion, etc., the spring 33A absorbs these displacements. Therefore, the contact state between the support member 30A and the camshaft 20 can always be maintained stably, preventing excessive stress concentration and wear.

[0044] (Regarding variants) In the second embodiment, the spring 33A is provided only for one support member 30A, but the other support member 35 may also be provided with a spring 33A in the same manner.

[0045] Furthermore, in each of the above embodiments, one support member 30, 35 is disposed at each end of cam rib 21, but multiple support members may be disposed at each end of cam rib 21. In this case, the rollers disposed at each end of cam rib 21 may be formed to the same thickness, with one roller disposed on the thicker side of cam rib 21 and multiple rollers (for example, two) disposed on the thinner side.

[0046] In the above embodiment, the rolling support member 14 has been described as a cam follower, but it may be any member that is fixed to the rotary table 12 and supports rotational motion while making rolling contact with the cam rib 21, such as a roller, a bearing roller, or a ball follower.

[0047] Furthermore, the shim 40 is provided as a single piece common to the pair of support members 30, 35, but it may also be provided as a separate piece for each of the support members 30, 35.

[0048] Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as the present invention or within an equivalent scope. [Industrial Applicability]

[0049] The present invention is advantageously used in machine tools. [Explanation of symbols]

[0050] 1, 1A: Rotary table device 10: Rotary table device main body (main body) 11: Lid part 12: Rotating table 12a: Table spindle 13: Turret 14: Rolling support member (cam follower) 20: Camshaft 21: Camlib 30, 30A: First support member 31, 31A: First fixing member 32: First roller 33A: Elastic member (spring) 35: Second support member 36: Second fixing member 37: Second roller 40: Sim

Claims

1. a rotary table device main body; a rotary table rotatably supported on the rotary table device main body via a table main shaft; a turret fixed to the table spindle; a plurality of rolling support members fixed to the turret; a camshaft having cam ribs formed on its outer periphery, the cam ribs being in rolling contact with the rolling support member; a pair of support members that are disposed on the opposite side of the table spindle as viewed from the camshaft and support both ends of the cam rib of the camshaft toward the table spindle, the support member includes a roller whose outer circumferential surface is in rotational contact with the camshaft, The cam rib is formed so that the rib thickness becomes thinner from one side to the other side in the rotation direction of the camshaft, The rollers arranged on the thinner rib side are formed thicker than the rollers arranged on the thicker rib side.

2. the support member further includes a fixing member fixed to the rotary table device main body, 2. The rotary table apparatus according to claim 1, wherein the roller is rotatably supported by the fixed member.

3. 3. The rotary table apparatus according to claim 1, wherein the rollers are disposed at opposite circumferential ends of the cam rib so as to be spaced apart from each other.

4. the rotary table device main body includes a lid for attaching the support member facing the camshaft, 3. The rotary table apparatus according to claim 1, wherein a shim is interposed between the cover portion and the support member.

5. 3. The rotary table apparatus according to claim 2, wherein the fixed member has an elastic member that elastically supports a load from the roller.

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