Machine tool

Abstract

To provide a machine tool which facilitates securing a space below a screw shaft.SOLUTION: A machine tool includes: a column extending in a vertical direction; a bearing which is fixed to the column at a position separated upward from a lower end of the column; a screw shaft which is rotatably supported by the bearing and extends downward from the bearing; a nut which is screwed with the screw shaft; a spindle head having an insertion section into which the screw shaft is inserted and being fixed to the nut; and a motor which generates driving force to rotate the screw shaft. The screw shaft is not directly supported by both the insertion section and the column below the nut.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a machine tool.

Background Art

[0002] As an example of a machine tool, there is a NC machine tool. The NC machine tool includes a machining table, a spindle motor that rotates a tool attached to a spindle head, and a Z-axis motor that moves the spindle head up and down (in the Z direction) via a ball screw and a nut (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a NC machine tool, the lower end of the ball screw is rotatably supported by a lower end bearing. Due to the presence of the lower end bearing, there has been a problem in the NC machine tool that it is difficult to secure a space below the ball screw (i.e., the screw shaft).

[0005] An object of the present disclosure is to provide a machine tool in which it is easy to secure a space below the screw shaft.

Means for Solving the Problems

[0006] A machine tool according to an aspect of the present disclosure includes a column extending in the vertical direction, a bearing fixed to the column at a position above the lower end of the column, a screw shaft rotatably supported by the bearing and extending below the bearing, a nut screwed onto the screw shaft, a spindle head having an insertion portion through which the screw shaft is inserted and fixed to the nut, and a motor that generates a driving force for rotating the screw shaft. The screw shaft is not directly supported by both the insertion portion and the column below the nut.

Advantages of the Invention

[0007] According to an exemplary disclosure, it is easy to secure a space below the screw shaft.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] [Embodiment] Hereinafter, a machine tool 100 according to an exemplary embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and the description will not be repeated.

[0010] [Definition of Directions] In the embodiments, for ease of understanding, in some of the figures, the first direction Z, the second direction X, and the third direction Y that intersect each other are appropriately described. In this specification, the term "intersect" includes the case where lines, planes, or lines and planes intersect at right angles to each other, and the case where they intersect at non-right angles within a slight difference range. The slight difference is a concept including, for example, tolerance and error.

[0011] One side and the other side of the first direction Z are described as the first direction one side Z1 and the first direction the other side Z2, respectively. One side and the other side of the second direction X are described as the second direction one side X1 and the second direction the other side X2, respectively. One side and the other side of the third direction Y are described as the third direction one side Y1 and the third direction the other side Y2, respectively.

[0012] In the embodiments, the "vertical direction" is the first direction Z, which is the vertical direction when the machine tool 100 is installed on the installation surface in the posture generally used for the machine tool 100 (hereinafter referred to as the "usage posture"). The installation surface 1 is a flat surface, for example, the floor surface of a factory. The "upward direction" is the first direction one side Z1. The "downward direction" is the first direction the other side Z2. Hereinafter, there may also be cases where they are described as the upward direction Z1 and the downward direction Z2.

[0013] Hereinafter, unless otherwise specified, the term "machine tool 100" may mean the machine tool 100 in the usage posture.

[0014] In the embodiments, the "front-rear direction" of the machine tool 100 is the second direction X. The "front direction" is the second direction one side X1. The "rear direction" is the second direction the other side X2. Hereinafter, there may also be cases where they are described as the front direction X1 and the rear direction X2.

[0015] The "left-right direction" is defined from the machine tool 100 toward the front direction X1. In the embodiments, the "left-right direction" is the third direction Y. The "left direction" is the third direction one side Y1. The "right direction" is the third direction the other side Y2. Hereinafter, there may also be cases where they are described as the left direction Y1 and the right direction Y2.

[0016] As shown in FIGS. 1 and 2, the machine tool 100 is installed in a use posture on an installation surface (not shown). The machine tool 100 is, for example, a vertical machining center.

[0017] The machine tool 100 includes a bed (not shown). The bed is made of cast iron and supports the following main components. The machine tool 100 includes, as main components, a column 1, a bearing 2, a screw shaft 3, a nut 4, a spindle head 5, and a motor 6. The spindle head 5 is an example of the "spindle head" in the present disclosure.

[0018] The column 1 is fixed on a bed (not shown) and extends in the vertical direction Z.

[0019] The column 1 has a bracket 13 at a position closer to the upper end portion 12 than the lower end portion 11. The lower end portion 11 and the upper end portion 12 are the ends in the downward direction Z2 and the upward direction Z1 in the column 1. The bracket 13 projects forward in the X1 direction from the column 1 in more detail. Thereby, a space 14 in which the spindle head 5 and the screw shaft 3 can be arranged is formed in the downward direction Z2 from the bracket 13. In the embodiment, the bracket 13 is plate-shaped and thin in the vertical direction Z and extends in the front-rear direction X and the left-right direction Y. The bracket 13 supports the bearing 2.

[0020] The bearing 2 is fixed to the bracket 13. That is, the bearing 2 is fixed to the column 1 at a position farther in the upward direction Z1 than the lower end portion 11 of the column 1. Specifically, the bearing 2 is arranged on the bracket 13 so that the center line (rotation axis) of the bearing 2 extends along the vertical direction Z.

[0021] The screw shaft 3 is rotatably supported by the bearing 2. The screw shaft 3 extends in the downward direction Z2 from the bearing 2 in a state of being supported by the bearing 2. Specifically, the screw shaft 3 extends in the space 14 in the downward direction Z2 from the bearing 2 and the bracket 13. The screw shaft 3 is a long bar shape in the vertical direction Z. A male screw is formed on the peripheral surface of the screw shaft 3.

[0022] The nut 4 is screwed onto the screw shaft 3. A female thread is formed on the peripheral surface of the through hole in the nut 4. The nut 4 is fixed to the spindle head 5.

[0023] The spindle head 5 has an insertion portion 51. The screw shaft 3 is inserted into the insertion portion 51. In the embodiment, the insertion portion 51 is a semi-through hole that is long in the vertical direction Z of the spindle head 5. The semi-through hole is a bottomed hole that linearly extends downward Z2 from the upper surface 52 of the spindle head 5. Note that the insertion portion 51 is not limited to a semi-through hole and may be a through hole. The through hole penetrates between the upper surface 52 and the lower surface 53 of the spindle head 5 and linearly extends downward Z2.

[0024] The spindle head 5 is further fixed to the nut 4. Specifically, in the insertion portion 51 (i.e., the semi-through hole), at a portion closer to the upper end portion 512 than the lower end portion 511, the spindle head 5 is fixed to the nut 4.

[0025] The motor 6 generates a driving force for rotating the screw shaft 3. In the embodiment, the column 1 has a motor mounting portion 16. The motor mounting portion 16 protrudes forward X1 from the column 1 at a position in the upward Z1 direction from the bracket 13. The motor mounting portion 16 is thin in the vertical direction Z and has a plate shape that expands in the front-rear direction X and the left-right direction Y. The motor 6 is attached to the motor mounting portion 16 by screws 61 or the like. The output shaft 62 of the motor 6 is connected to the screw shaft 3 via a driving force transmission mechanism 63. The driving force generated by the motor 6 is converted into a force for moving the spindle head 5 in the vertical direction Z by the screw shaft 3 and the nut 4. Thereby, the spindle head 5 moves in the vertical direction Z.

[0026] The screw shaft 3 is not directly supported by both the insertion portion 51 and the column 1 in the downward direction Z2 from the nut 4. With this configuration, it is possible to provide a machine tool 100 in which it is easier to secure a space below the screw shaft 3 as compared with the case where the lower end portion 31 of the screw shaft 3 is supported by a bearing. That is, for example, a space can be secured below the screw shaft 3, that is, below the spindle head 5, as compared with the case where the lower end portion 31 of the screw shaft 3 is supported by a bearing fixed to the column 1 in the downward direction Z2 from the lower end portion of the spindle head 5. Note that the screw shaft 3 is in direct contact with the nut 4 in the semi-through hole of the insertion portion 51, but is separated from the spindle head 5 (that is, the insertion portion 51).

[0027] As shown in FIGS. 1 to 4, the machine tool 100 further includes a rail 71 and a block 72. The rail 71 is fixed to the column 1 and is located away from the screw shaft 3 in the left-right direction Y that intersects the up-down direction Z. The left-right direction Y is an example of a first direction in the present disclosure. The rail 71 extends in the up-down direction Z. The block 72 is fixed to the spindle head 5. The block 72 is movable on the rail 71. With this configuration, the spindle head 5 moves with high precision along the up-down direction Z as compared with the case where there are no rail 71 and block 72. Further, even when the lower end portion 31 of the screw shaft 3 is not directly supported by the insertion portion 51 or the column 1 by a bearing or the like, the spindle head 5 can move with high precision along the up-down direction Z.

[0028] As shown in FIGS. 3 and 4, there are two rails 71. The two rails 71 are separated from each other in the left-right direction Y. There are a plurality of blocks 72. The plurality of blocks 72 are movable on the two rails 71. With this configuration, the spindle head 5 moves with high precision along the up-down direction Z as compared with the case where there is one rail 71 and one block 72.

[0029] More specifically, as shown in FIG. 4, the two rails 71 are fixed to the front surface 17 of the column 1 and are provided on both sides of the spindle 54 in the left - right direction Y in a front view. Hereinafter, the rail 71 provided in the left direction Y1 of the spindle 54 is also referred to as the "left rail 71". On the other hand, the rail 71 provided in the right direction Y2 of the spindle 54 is also referred to as the "right rail 71".

[0030] Each rail 71 has a guide surface 711. Each guide surface 711 faces the forward direction X1 and is a flat surface that extends in the vertical direction Z and the left - right direction Y. The two guide surfaces 711 may be symmetric with each other in the left - right direction Y.

[0031] As shown in FIG. 4, each of the plurality of blocks 72 is provided on the back surface 56 of the spindle head 5. Among the plurality of blocks 72, two blocks 72 engage with the left rail 71, and the remaining two blocks 72 engage with the right rail 71. Thereby, each block 72 does not fall off from each rail 71. As a result, the spindle head 5 moves with high precision along the vertical direction Z as compared with the case where each block 72 does not engage with each rail 71.

[0032] Also, each block 72 has a slide surface 721. Each slide surface 721 faces the rearward direction X2 and is a flat surface that extends in the vertical direction Z and the left - right direction Y. Each slide surface 721 contacts each guide surface 711. Therefore, when the spindle 5 moves in the vertical direction Z, the slide surface 721 slides on the guide surface 711. Thereby, the spindle head 5 moves with high precision along the vertical direction Z.

[0033] The spindle head 5 has a spindle 54 that rotates a tool for performing various machining operations. In the front-rear direction X that intersects the vertical direction Z and the left-right direction Y, the screw shaft 3 is positioned closer to the spindle 54 than the block 72 or the rail 71. The front-rear direction X is an example of the "second direction" of the present disclosure. With this configuration, since the distance between the spindle 54 and the screw shaft 3 is shortened, the machining accuracy by the tool is improved. That is, compared with the case where the screw shaft is disposed at a location farther from the spindle than the block or the rail, since the screw shaft 3 is disposed closer to the spindle 54 than the block 72 or the rail 71, the moment applied to the spindle 54 with respect to the screw shaft 3 is reduced, so that the influence of vibration in the spindle 54 and the load applied to the spindle 54 is reduced and the machining accuracy is improved. Note that the tool is rotatably and detachably attached to the spindle 54. The tool rotates by the driving force generated by the motor 55. The motor 55 is fixed to the spindle head 5.

[0034] Specifically, in a state where the spindle head 5 is positioned at the uppermost position Z1 in the vertical direction Z, the lower end portion 31 of the screw shaft 3 is above the lower end portion 513 of the spindle head 5. In other words, in a state where the spindle head 5 is positioned at the uppermost position Z1, the lower end portion 31 does not protrude downward Z2 more than the lower end portion 513. With this configuration, the space secured in the downward Z1 direction of the screw shaft 3 becomes wider.

[0035] In the vertical direction Z, the lower end portion 511 of the insertion portion 51 is at the same position as the lower end portion 513 of the spindle head 5 or above the lower end portion 513 of the spindle head 5. With this configuration, the space secured in the downward Z1 direction of the screw shaft 3 becomes wider. Specifically, when the insertion portion 51 is a through hole, the lower end portion 511 of the insertion portion 51 is at the same position as the lower end portion 513 of the spindle head 5. On the other hand, when the insertion portion 51 is a semi-through hole, the lower end portion 511 of the insertion portion 51 is above the lower end portion 513 of the spindle head 5.

[0036] As shown in FIG. 2, the machine tool 100 further includes a table 8 and a moving mechanism 9. A workpiece is placed on the table 8. Specifically, the workpiece is placed on the upper surface of the table 8. The moving mechanism 9 moves the table 8 within a range including the downward direction Z2 of the screw shaft 3. With this configuration, it becomes possible to move the workpiece over a wide range including the downward direction Z2 of the screw shaft 3. Therefore, the degree of freedom in machining the workpiece, which is the object to be machined by the tool, is improved. Note that the moving mechanism 9 can be realized by a known ball screw conveyance mechanism.

[0037] As described above, the motor 6 is attached to the motor attachment portion 16 by a screw 61 or the like. That is, the motor 6 is located in the upward direction Z1 of the screw shaft 3. Therefore, a load by the motor 6 is applied to a portion close to the column 1 in the upward direction Z1 of the spindle head 5. As a result, compared with the case where the motor 6 is located at a portion close to the spindle 54 in the upward direction Z1 of the spindle head 5, the spindle 54 is less likely to sag in the downward direction Z2.

[0038] Also, the drawings schematically show each component mainly for facilitating the understanding of the present disclosure, and the thickness, length, number, interval, etc. of each illustrated component may be different from the actual ones for convenience in drawing preparation. Further, the configuration of each component shown in the above embodiment is an example and is not particularly limited, and it goes without saying that various changes can be made without substantially departing from the effects of the present disclosure.

[0039] Note that the present technology can also adopt the following configuration.

[0040] (1) A column extending in the vertical direction, a bearing fixed to the column at a position farther above than the lower end portion of the column, a screw shaft rotatably supported by the bearing and extending downward from the bearing, a nut screwed onto the screw shaft, a spindle head having an insertion portion through which the screw shaft is inserted and fixed to the nut, A motor that generates a driving force for rotating the screw shaft, and is provided with, The screw shaft is not directly supported by both the insertion portion and the column below the nut, a machine tool.

[0041] (2) A rail that is fixed to the column, is located away from the screw shaft in a first direction intersecting the vertical direction, and extends in the vertical direction, and a block that is fixed to the spindle head and is movable on the rail The machine tool according to (1), further comprising.

[0042] (3) Two rails separated from each other in the first direction, and a plurality of the blocks movable on the two rails The machine tool according to (2), further comprising.

[0043] (4) The spindle head has a spindle for rotating a tool, In a second direction intersecting the vertical direction and the first direction, the screw shaft is located closer to the spindle than the block or the rail. The machine tool according to any one of (1) to (3).

[0044] (5) With the spindle head located at the uppermost position in the vertical direction, the lower end of the screw shaft is above the lower end of the spindle head. The machine tool according to any one of (1) to (4).

[0045] (6) In the vertical direction, the lower end of the insertion portion is at the same position as the lower end of the spindle or above the lower end of the spindle. The machine tool according to any one of (1) to (5).

[0046] (7) A table on which a workpiece is placed, and a moving mechanism for moving the table within a range including below the screw shaft The machine tool according to any one of (1) to (6), further comprising.

[0047] (8) The main spindle head has a main spindle for rotating a tool, The motor is located above the screw shaft, and the machine tool according to any one of (1) to (7).

Industrial Applicability

[0048] The present disclosure can be used, for example, in a machine tool and has industrial applicability.

Explanation of Signs

[0049] 100: Machine tool 1: Column 11: Lower end 12: Upper end 2: Bearing 3: Screw shaft 31: Lower end 4: Nut 5: Spindle head 51: Insertion part 511: Lower end 512: Upper end 513: Lower end 54: Spindle 55: Motor 6: Motor 71: Rail 72: Block 8: Table 9: Moving mechanism

Claims

1. a column extending in the vertical direction; a bearing fixed to the column at a position above the lower end of the column; a screw shaft rotatably supported by the bearing and extending below the bearing; a nut screwed onto the screw shaft; a spindle head having an insertion portion through which the screw shaft is inserted and fixed to the nut; a motor that generates a driving force for rotating the screw shaft; comprising; a machine tool, wherein the screw shaft is not directly supported by both the insertion portion and the column below the nut.

2. a rail fixed to the column, located away from the screw shaft in a first direction intersecting the vertical direction, and extending in the vertical direction; a block fixed to the spindle head and movable on the rail; The machine tool according to claim 1, further comprising.

3. two rails spaced apart from each other in the first direction; a plurality of the blocks movable on the two rails; The machine tool according to claim 2, further comprising.

4. the spindle head has a spindle for rotating a tool; In a second direction intersecting the vertical direction and the first direction, the screw shaft is located closer to the spindle than the block or the rail. The machine tool according to claim 2 or claim 3.

5. The machine tool according to any one of claims 1 to 3, wherein in a state where the spindle head is located at the uppermost position in the vertical direction, the lower end of the screw shaft is above the lower end of the spindle head.

6. In the vertical direction, the lower end of the insertion portion is at the same position as the lower end of the spindle head or above the lower end of the spindle head. The machine tool according to claim 5.

7. a table on which a workpiece is placed; a moving mechanism for moving the table within a range including below the screw shaft; The machine tool according to any one of claims 1 to 3, further comprising.

8. the spindle head has a spindle for rotating a tool; The motor is located above the screw shaft. The machine tool according to any one of claims 1 to 3.

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