Machine tool

Abstract

The utility model relates to a machine tool, which comprises a main shaft used for clamping a workpiece; and a selectable portion mounted on a part of the machine tool such that the stroke of the spindle or the tailstock is not limited, the selectable portion moving to a standby position when not in use and moving to a support position when in use, depending on the type of workpiece clamped on the spindle, and the selectable portion moving to a support position when in use, depending on the type of workpiece clamped on the spindle. And the main shaft is used for selectively supporting the workpiece clamped on the main shaft.

Description

Technical Field

[0001] This utility model relates to a machine tool, and more specifically, to a machine tool in which the travel of the spindle or tailstock is unrestricted by configuring an optional part on a portion of the machine tool. Background Technology

[0002] Generally speaking, a machine tool is a machine used to process metal / non-metal workpieces into the required shape and size by means of appropriate cutting or non-cutting tools.

[0003] Machine tools of various types, such as turning centers, vertical / horizontal machining centers, gantry machining centers, switch machines, electrical discharge machines, horizontal NC drilling machines, and CNC lathes, are widely used in various industrial settings according to their respective applications.

[0004] Generally, many machine tools currently in use have a control console that utilizes numerical control (NC) or CNC (computerized numerical control) technology. This control console has various function switches or buttons and a monitor.

[0005] In addition, in order to perform various machining operations, machine tools generally use multiple cutting tools, and use a tool magazine or turret in the form of a tool storage area to house and store multiple cutting tools.

[0006] Generally, in order to improve the productivity of machine tools, machine tools are equipped with an automatic tool changer (ATC). The automatic tool changer retrieves or reloads a specific tool from the tool magazine through commands from the CNC unit.

[0007] In addition, to minimize non-machining time, machine tools are generally equipped with an Automatic Palette Changer (APC). The APC automatically exchanges pallets between the workpiece machining area and the workpiece setting area. Workpieces can be loaded onto the pallets.

[0008] In addition, the machine tool includes: a transfer table for placing workpieces or materials and transferring workpieces for processing; a tray for preparing workpieces before processing; a spindle for rotating in connection with the cutting tool or workpiece; a tailstock for supporting the workpiece during processing; and a center rest, etc.

[0009] Generally, machine tools include transfer units such as transfer tables, tool holders, spindles, tailstocks, and center rests, which are moved along the transfer axis to perform various machining operations.

[0010] Generally, a steady rest is a device used to fix a workpiece (material being machined) that is long in length when machining on a turning center or CNC lathe, in order to prevent the workpiece from vibrating and shaking.

[0011] When the length of the workpiece (material being processed) is less than the predetermined length, the workpiece (material being processed) can be fixed to a certain extent by the tailstock, thereby preventing the workpiece (material being processed) from vibrating and causing errors during processing, and maintaining processing accuracy.

[0012] However, when the length of the workpiece (material being processed) exceeds the predetermined length, even if the workpiece (material being processed) is fixed by a tailstock, the vibration generated by the cutting tool during processing will still cause the workpiece (material being processed) to shake, resulting in processing errors and significantly increasing the rate of defective products.

[0013] Therefore, in order to solve these problems, when turning a workpiece (material to be machined) with a length greater than a predetermined length, a center rest is installed in addition to the tailstock to fix the workpiece (material to be machined) so that the workpiece does not wobble during the machining process.

[0014] The existing center frame consists of a base and a body structure that always occupy space, which limits the proximity of the tailstock (or sub-spindle).

[0015] That is, since the existing center frame is coaxially arranged with the spindle and / or tailstock, and the base and body structures used to install the center frame are also coaxially arranged with the spindle and / or tailstock, they always occupy space. Therefore, the stroke of the spindle and / or tailstock is limited by the space occupied by the center frame.

[0016] This limitation on travel is particularly severe on small machine tools, and due to the limitation of the center rest mounting position, there is a problem that the center rest cannot be applied to the machine tool itself.

[0017] Furthermore, if the installation positions of structures such as the base and body for mounting the center frame are not considered during the machine tool design phase, there is a problem that the center frame itself cannot be used.

[0018] Existing technical documents

[0019] Patent documents

[0020] (Patent Document 0001) Korean Patent Publication No. 10-2019-0096558 Utility Model Content

[0021] This invention is proposed to solve the above-mentioned problems. Its purpose is to provide a machine tool in which the travel of the spindle or tailstock is not limited by installing an optional part (e.g., a center rest) on a part of the machine tool. Depending on the type of workpiece clamped on the spindle, it can be moved to a standby position when not in use, and only moved to a support position when in use, selectively supporting the workpiece clamped on the spindle. Thus, after the setup step, the optional part can be used flexibly as needed to seek user convenience, while moving it to the standby position when not in use avoids interference and minimizes the setup space, thereby overcoming the travel limitation.

[0022] To achieve the purpose of this utility model, the following technical solution is adopted.

[0023] The machine tool according to this utility model may include: a spindle for clamping a workpiece; and an optional part installed on a part of the machine tool such that the stroke of the spindle is unrestricted. Depending on the type of workpiece clamped on the spindle, the optional part is moved to a standby position when not in use, and to a support position only when in use, so as to selectively support the workpiece clamped on the spindle.

[0024] Furthermore, in a preferred embodiment of the machine tool according to the present invention, the optional part may include: a base portion that rotates and moves linearly along the length direction according to the operation of the operating part; a pivot portion that is connected to a part of the base portion and moves linearly together with the base portion while pivoting in the width direction as the base portion rotates; a shaft portion that is rotatably disposed in the width direction at the front end of the pivot portion; and a support portion disposed at the front end of the shaft portion and pivoting in the width direction as the shaft portion rotates to support the workpiece clamped to the spindle.

[0025] Furthermore, in a preferred embodiment of the machine tool according to the present invention, the support portion may include: a housing portion having a pair of receiving portions; a pair of connecting portions having a block portion and a head that is vertically inserted into the block portion, the pair of connecting portions being inserted into the pair of receiving portions such that the head elastically supports the workpiece clamped on the spindle; and a pair of coupling portions connecting the pair of connecting portions to the housing portion.

[0026] Furthermore, in a preferred embodiment of the machine tool according to the present invention, the pair of connecting portions can be configured such that the coupling position of the pair of connecting portions connected to the housing portion is adjusted by changing the coupling position of the pair of connecting portions connected through the elongated hole formed on the housing portion according to the type of workpiece clamped on the spindle.

[0027] Furthermore, in a preferred embodiment of the machine tool according to the present invention, each of the block portions may include a guide groove portion extending in the width direction from the lower part of the block portion.

[0028] Furthermore, in a preferred embodiment of the machine tool according to the present invention, the support portion may further include a sensing unit for sensing the workpiece that is elastically supported by the head and clamped on the spindle.

[0029] Furthermore, in a preferred embodiment of the machine tool according to the present invention, the base portion may include: a mounting portion detachably mounted on a part of the machine tool; a track portion disposed on the mounting portion along the length direction; a moving portion that moves linearly along the track portion; and a rotating shaft rotatably disposed on the moving portion.

[0030] Furthermore, in a preferred embodiment of the machine tool according to the present invention, the operating part may include: a first operating part disposed on the mounting part for causing the moving part to move linearly; and a second operating part disposed on the moving part for causing the rotating shaft to rotate.

[0031] Furthermore, in a preferred embodiment of the machine tool according to the present invention, the optional part may further include a barrel portion disposed at the front end of the shaft portion. As the shaft portion rotates, it pivots in the width direction to discharge the workpiece clamped to the spindle and processed to the outside of the machine tool. The front end of the shaft portion may selectively connect either the support portion or the barrel portion, or the support portion and the barrel portion may be connected together.

[0032] Furthermore, in a preferred embodiment of the machine tool according to the present invention, a tailstock may also be included, which is arranged facing the spindle and spaced apart, for supporting the free end of the workpiece clamped on the spindle.

[0033] The effects of this utility model are as follows.

[0034] According to the present invention, by detachably installing an optional part on a part of the machine tool, the travel of the spindle or tailstock is not restricted, which overcomes the limitation of the space for setting the optional part. Especially when it is necessary to process long workpieces on a small machine tool, the quality of the workpiece can be improved by adding the optional part.

[0035] Furthermore, the machine tool according to this utility model has space that does not need to be considered from the design stage for installing optional parts, and optional parts can be flexibly and conveniently installed as needed in the future, thereby improving the convenience for users.

[0036] Furthermore, according to the machine tool of this invention, the optional part can be moved to the standby position when not in use, and only moved to the support position when in use. Therefore, it has the effect of avoiding travel limitations when in use and preventing interference with other equipment when not in use.

[0037] Furthermore, according to the present invention, since the machine tool is inserted and arranged in the block section in a way that allows for lifting and lowering, even if the length or diameter of the workpiece supported by the head changes slightly, various workpieces can be supported without further adjustment by moving the head up and down. Moreover, if the length or diameter of the workpiece changes significantly, the position of the pair of connecting parts connected to the housing section in the width direction can be adjusted by changing the coupling position of the pair of connecting parts connected by the elongated hole formed through the housing section. This results in the effect of supporting the workpiece in an accurate position according to the change in the length or diameter of the workpiece.

[0038] Furthermore, the machine tool according to this utility model, in addition to the support part (e.g., center rest), can also be used as a workpiece support device to maintain the correct position of the workpiece during the process of supporting the workpiece with the tailstock before processing. For example, in addition to the support part (e.g., center rest), the support part can be changed into a barrel part and used as a workpiece discharge device, etc. However, it is not limited to a workpiece discharge device. The support parts can be replaced as optional devices as needed, so that it can be modified and utilized in various ways to ensure the compatibility and versatility of the machine tool.

[0039] The effects of this invention are not limited to those described above. Those skilled in the art will clearly understand other effects not mentioned from the following description. Attached Figure Description

[0040] Figures 1 to 4 This illustrates the movement of an optional part of a machine tool, according to an embodiment of the present invention, from a standby position to a support position. Figure 1 This indicates that the optional unit is in the standby position. Figure 2 This shows the state of the base moving in a longitudinal straight line. Figure 3 This shows the state of the pivoting section during pivoting. Figure 4 This shows the state of the support component moving to the support position.

[0041] Figure 5 This is a perspective view of the support portion of an optional part of a machine tool according to an embodiment of the present invention.

[0042] Figure 6 A perspective view of the housing section is shown.

[0043] Figure 7 A perspective view of the connecting part is shown.

[0044] Figure 8(a) is a three-dimensional view of the block, and Figure 8(b) is a three-dimensional view of the head.

[0045] Figure 9 A cross-sectional view of a support portion of an optional part of a machine tool according to an embodiment of the present invention is shown.

[0046] Figure 10 This is a cross-sectional view showing the guide groove.

[0047] Figure 11 A perspective view showing the state of the support connecting barrel of an optional part of a machine tool according to an embodiment of the present invention.

[0048] Symbol Explanation

[0049] 100: Main spindle, 200: Tailstock, 300: Optional part, 310: Base part, 320: Pivot part, 330: Shaft part, 340: Support part. Detailed Implementation

[0050] The following is a detailed description of a machine tool according to an embodiment of the present invention, with reference to the accompanying drawings. The embodiments described below are provided as examples to fully convey the spirit of the present invention to those skilled in the art. Therefore, the present invention is not limited to the embodiments described below and can be embodied in other forms. Furthermore, in the drawings, the size and thickness of the device are shown enlarged for convenience. Throughout the specification, the same symbols denote the same constituent elements.

[0051] The advantages, features, and methods of achieving this invention will become clear from the accompanying drawings and the embodiments described below. However, this invention is not limited to the following embodiments and can be embodied in various other forms. These embodiments make the disclosure of this invention more complete and provide a full scope of invention for those skilled in the art. Throughout the specification, the same reference numerals denote the same constituent elements. For clarity, the dimensions and relative dimensions of layers and regions in the figures are shown enlarged.

[0052] The terminology used in this specification is for illustrative purposes and does not limit the present invention. Unless otherwise specified in this specification, the singular form also includes the plural form. The terms "comprise" and / or "comprising" as used in this specification mean that the mentioned constituent elements, steps, actions, and / or components do not exclude the presence or addition of more than one other constituent element, step, action, and / or component.

[0053] Figures 1 to 4 This illustrates the movement of an optional part of a machine tool, according to an embodiment of the present invention, from a standby position to a support position.

[0054] Figure 1This indicates that the optional unit is in the standby position. Figure 2 This shows the state of the base moving in a longitudinal straight line. Figure 3 This shows the state of the pivoting section during pivoting. Figure 4 This shows the state of the support component moving to the support position.

[0055] Figure 5 This is a perspective view of the support portion of an optional part of a machine tool according to an embodiment of the present invention. Figure 6 A perspective view of the housing section is shown.

[0056] Figure 7 A perspective view of the connecting part is shown. Figure 8(a) is a perspective view of the block part, and Figure 8(b) is a perspective view of the head.

[0057] Figure 9 A cross-sectional view of a support portion of an optional part of a machine tool according to an embodiment of the present invention is shown. Figure 10 This is a cross-sectional view showing the guide groove.

[0058] Figure 11 A perspective view showing the state of the support connecting barrel of an optional part of a machine tool according to an embodiment of the present invention.

[0059] Reference Figures 1 to 11 The machine tool 1 of this utility model will be described.

[0060] like Figures 1 to 11 As shown, in the case of turning a workpiece (material to be processed) with a length of more than a predetermined length, the machine tool 1 according to the present invention is provided with a center rest without stroke limitation in addition to the tailstock to prevent the workpiece (material to be processed) from shaking during the processing.

[0061] In addition to serving as a center support, it can also be used as a workpiece support device to maintain the correct position of the workpiece during the process of supporting the workpiece with a tailstock before machining.

[0062] In addition, for example, besides the center frame, the support part can be changed into a barrel part and used as a workpiece discharge device, etc., but it is not limited to a workpiece discharge device. As needed, the support part can be replaced as an optional device.

[0063] The machine tool 1 according to the present invention includes: a spindle 100 and an optional part 300.

[0064] Furthermore, the machine tool 1 according to this utility model may include a tailstock 200 in addition to the spindle 100 and the optional part 300. The tailstock is arranged facing and spaced apart from the spindle 100 to support the free end of the workpiece clamped on the spindle 100.

[0065] According to this utility model, the spindle 100 of the machine tool 1 is arranged to clamp workpieces 2 and 3.

[0066] The spindle 100 of machine tool 1 can clamp many types of workpieces. For example, the length or diameter of the workpiece may change, and the material of the workpiece, such as its hardness, may also change.

[0067] According to the present invention, the tailstock 200 of the machine tool 1 faces the spindle 100 and is arranged at a distance to support the free ends of the workpieces 2 and 3 that are clamped on the spindle 100.

[0068] When the length of the workpiece (material to be processed) is less than the predetermined length, the workpiece (material to be processed) can be fixed to a certain extent by the tailstock, thereby preventing the workpiece (material to be processed) from vibrating and causing errors during processing, and maintaining processing accuracy.

[0069] The optional part 300 of the machine tool 1 according to the present invention can be installed on a part of the machine tool 1, so that the stroke of the spindle 100 is not limited.

[0070] Alternatively, the optional part 300 of the machine tool 1 according to the present invention can be detachably mounted on a part of the machine tool 1, so that the stroke of the spindle 100 is unrestricted.

[0071] Furthermore, the optional part 300 can be detachably mounted on a portion of the machine tool 1, such that when the tailstock 200 is further configured to face and be spaced apart from the spindle to support the free end of the workpiece clamped on the spindle, the travel of the tailstock 200 is not limited.

[0072] As mentioned above, when the length of the workpiece (material being machined) is less than the predetermined length, a certain machining accuracy can be maintained by the tailstock. However, when the length of the workpiece (material being machined) is greater than the predetermined length, even if the workpiece (material being machined) is fixed by the tailstock, the vibration generated on the cutting tool during machining will cause the workpiece (material being machined) to wobble, resulting in machining errors and a significant increase in the rate of defective products.

[0073] Therefore, in order to solve these problems, when turning a workpiece (material to be machined) with a length greater than a predetermined length, a center rest (optional) is installed in addition to the tailstock to fix the workpiece (material to be machined) so that it does not wobble during the machining process.

[0074] The part of machine tool 1 refers to the part that provides space for the machine tool housing (not shown), spindle 100, tailstock 200, etc.

[0075] For example, such as Figures 1 to 4As shown, the optional part 300 can be detachably mounted on a part of the spindle 100.

[0076] Furthermore, the optional part 300 can be configured not on the same line as the main spindle 100 or the tailstock 200 when the main spindle 100 or the tailstock 200 is configured on the same axis, so that the stroke of the main spindle 100 or the tailstock 200 is not limited.

[0077] Thus, according to the present invention, by detachably installing the optional part on a part of the machine tool, the stroke of the spindle or tailstock is not limited, thereby overcoming the limitation of the installation space of the optional part. Especially in the case of small machine tools that need to process long workpieces, the quality of the workpiece can be improved by additional installation.

[0078] Furthermore, the machine tool according to this utility model can flexibly and conveniently install optional parts as needed in the future, without having to consider the space for installing optional parts from the design stage, thereby seeking user convenience.

[0079] Reference Figures 1 to 4 The optional unit 300 can be moved to a standby position when not in use, depending on the type of workpieces 2 and 3 clamped on the spindle 100. Figure 1 The position), and only moves to the support position when in use ( Figure 4 The position of the spindle 100 is used to selectively support the workpieces 2 and 3 that are clamped on the spindle 100.

[0080] Thus, the machine tool according to this invention can avoid travel limitations during use and prevent interference with other equipment when not in use by moving the optional part to the standby position and only moving it to the support position when in use.

[0081] Specifically, the optional part 300 may include: a base part 310, a pivot part 320, a shaft part 330, and a support part 340.

[0082] The base portion 310 may specifically include an operation portion 311, a mounting portion 312, a track portion 313, a moving portion 314, and a rotating shaft 315.

[0083] The base 310 can rotate according to the operation of the operation unit 311 and move linearly along the length direction.

[0084] The operation unit 311 may include a first operation unit 3111 and a second operation unit 3112.

[0085] The first operating unit 3111 is disposed on the mounting unit 312 and causes the moving unit 314 to move linearly.

[0086] That is, through the operation of the first operation unit 3111, the moving unit 314 can move linearly along the length direction.

[0087] The second operating part 3112 is disposed on the moving part 314, which can rotate the rotating shaft 315.

[0088] Mounting section 312 is detachably mounted on a part of machine tool 1. Figures 1 to 4 In the middle, the mounting part 312 is formed in the shape of a plate, but is not limited to this.

[0089] The track section 313 is longitudinally arranged on the mounting section 312 and moves the moving section 314.

[0090] The track section 313 is not limited to this and may be constructed using LM guide rails or the like.

[0091] The moving part 314 moves linearly along the track part 313, and the rotating shaft 315 is rotatably disposed on the moving part 314.

[0092] The pivoting part 320 is connected to a portion of the base part 310 and moves linearly together with the base part 310. At the same time, it can pivot in the width direction as the base part 310 rotates.

[0093] Specifically, the pivoting part 320 is connected to the front end of the rotating shaft 315, which is part of the base part 310, and pivots in the width direction as the rotating shaft 315 rotates. Furthermore, the pivoting part 320 moves linearly together with the rotating shaft 315, which moves linearly as the moving part 314 moves linearly.

[0094] The shaft portion 330 is rotatably disposed at the front end of the pivot portion 320 in the width direction.

[0095] The support portion 340 is disposed at the front end of the shaft portion 330 and pivots in the width direction as the shaft portion 330 rotates to support the workpiece 2 clamped on the main shaft 100.

[0096] Specifically, the support portion 340 may include: a housing portion 341, a connecting portion 342, a coupling portion 343, and a sensing portion 344.

[0097] Reference Figure 5 and Figure 6 The housing portion 341 has a pair of receiving portions 3411, in which the connecting portion is respectively received.

[0098] Furthermore, elongated holes 3412 are formed in the upper and lower parts of the housing portion 341, and coupling portions 343 are coupled in the elongated holes to fix the housing portion and the connecting portion.

[0099] Furthermore, a guide hole 3413 is formed through the lower surface of the housing portion 341, and a guide portion 3423 is coupled through the guide hole 3413. A portion of the coupled guide portion 3423 is accommodated in the guide groove portion 34211 of the block portion 3421.

[0100] The connecting parts 342 are a pair, and each connecting part 342 may include a block part 3421 and a head 3422 that can be inserted into the block part 3421.

[0101] Furthermore, the connecting portion 342 is inserted into each of the pair of receiving portions 3411, such that the head 3422 elastically supports the workpiece clamped onto the spindle 100.

[0102] Refer to Figures 8(a), 8(b) and... Figure 10 The block portion 3421 may have a guide groove 34211 extending in the width direction at its lower part.

[0103] Furthermore, as described above, a guide hole 3413 is formed through the lower surface of the housing portion 341, and a guide portion 3423 is coupled through the guide hole 3413. A portion of the coupled guide portion 3423 is accommodated in the guide groove portion 34211 of the block portion 3421.

[0104] Thus, when the guide groove 34211 extends in the width direction and a portion of the guide 3423 is accommodated in the guide groove 34211 of the block 3421, the width direction position of the pair of connecting portions 342 connected to the housing 341 can be adjusted by changing the coupling position of the pair of connecting portions 343 connected by the pair of connecting portions through the elongated hole 3412 formed in the housing 341, thus preventing the block from falling off in a direction other than the width direction.

[0105] This is because the guide portion 3423, which is partially housed in the guide groove portion 34211, restricts the block portion from moving in a direction other than the width direction.

[0106] Thus, when the width direction position of the pair of connecting parts 342 connected to the housing part 341 via the pair of coupling parts 343 is adjusted, the block part also moves only in the width direction via the guide groove part 34211, thereby allowing the workpiece support position to be precisely adjusted without error.

[0107] The head 3422 may include: a column portion 34221, a rest portion 34222, a roller portion 34223, and an elastic portion 34224.

[0108] The column portion 34221 is inserted into the block portion 3421, the rest portion 34222 is connected to one end of the column portion 34221, the roller portion 34223 is rotatably connected to the rest portion, and the elastic portion 34224 is inserted into the outer peripheral surface of the column portion.

[0109] The coupling portions 343 are formed in a pair for coupling the pair of connecting portions 342 to the housing portion 341 respectively.

[0110] Specifically, the coupling part 343 is coupled through the elongated hole 3412 of the housing part 341 and the coupling receiving part 34213 of the block part 3421, thereby connecting the block part 3421 to the housing part 341.

[0111] Furthermore, the pair of connecting portions 342 can be adjusted in the width direction by changing the coupling position of the pair of coupling portions 343 connected by the elongated hole 3412 formed through the housing portion 341 according to the type of workpieces 2 and 3 clamped on the spindle 100.

[0112] Thus, according to the present invention, since the machine tool is vertically and vertically inserted into the block, even if the length or diameter of the workpiece supported by the head changes slightly, various workpieces can be supported without further adjustment by moving the head vertically. Furthermore, if the length or diameter of the workpiece changes significantly, the width direction position of the pair of connecting parts connected to the housing part can be adjusted by changing the coupling position of the pair of connecting parts connected by the elongated hole formed through the housing part. In this way, the workpiece can be supported in an accurate position in accordance with the change in the length or diameter of the workpiece.

[0113] The sensing unit 344 is used to sense the workpiece that is elastically supported and clamped on the spindle 100 by the head 3422.

[0114] For example, when the elastic part 34224 disposed on the column 34221 is a spring, the sensing part 344 can sense that the workpiece is supported by the density of the spring. When the density of the spring is high, it can sense that the workpiece is supported.

[0115] Reference Figure 11 According to another embodiment of the present invention, the optional part 300 of the machine tool 1 may further include a barrel part 350, which is disposed at the front end of the shaft part 330 and pivots in the width direction as the shaft part 330 rotates, so as to discharge the workpiece that has been clamped on the spindle 100 and processed to the outside of the machine tool.

[0116] Specifically, one of the support portion 340 or the barrel portion 30 can be selectively connected to the front end of the shaft portion 330.

[0117] Alternatively, the support portion 340 and the barrel portion 350 can be connected together at the front end of the shaft portion 330.

[0118] Furthermore, the machine tool according to this invention, in addition to the support part (e.g., the center rest), can also be used as a support device for the workpiece during the process of supporting the workpiece with the tailstock before processing, so as to maintain the correct position of the workpiece.

[0119] For example, in addition to the support section (e.g., the center frame), the support section can be changed into a barrel section for use as a workpiece discharge device, or the support section and the barrel section can be combined for use.

[0120] That is, it is not limited to the workpiece discharge device. The support part can be replaced as an optional device as needed. Therefore, it can be modified and used in a variety of ways, thereby ensuring the compatibility and versatility of the machine tool.

Claims

1. A machine tool, characterized by Comprising: a main shaft for clamping a workpiece; and an optional portion installed at a portion of the machine tool such that a stroke of the main shaft is not limited, the optional portion is moved to a standby position when not used and to a support position only when used to selectively support the workpiece clamped on the main shaft according to a type of the workpiece clamped on the main shaft. 2.The machine tool according to claim 1, wherein the optional portion comprises: a base portion that rotates and linearly moves in a length direction according to an operation of an operation portion; a pivot portion that is coupled to a portion of the base portion and pivots in a width direction as the base portion rotates while linearly moving with the base portion; a shaft portion that is rotatably disposed in the width direction at a front end of the pivot portion; and a support portion that is disposed at a front end of the shaft portion and pivots in the width direction as the shaft portion rotates to support the workpiece clamped on the main shaft. 3.The machine tool according to claim 2, wherein the support portion comprises: a housing portion having a pair of accommodation portions; a pair of coupling portions each having a block portion and a head portion that is insertable in the block portion in a liftable manner, the pair of coupling portions being inserted into the pair of accommodation portions, respectively, such that the head portion elastically supports the workpiece clamped on the main shaft; and a pair of coupling portions that couple the pair of coupling portions to the housing portion, respectively. 4.The machine tool according to claim 3, wherein the pair of coupling portions are configured to adjust a position in the width direction of the pair of coupling portions coupled to the housing portion by changing a coupling position of the pair of coupling portions coupled to the housing portion according to a type of the workpiece clamped on the main shaft. 5.The machine tool according to claim 4, wherein each of the block portions includes a guide groove portion that extends in the width direction at a lower portion of the block portion. 6.The machine tool according to claim 3, wherein the support portion further comprises a sensing unit for sensing that the head portion elastically supports the workpiece clamped on the main shaft. 7.The machine tool according to claim 2, wherein the base portion comprises: a mounting portion that is detachably mounted at a portion of the machine tool; a rail portion that is disposed on the mounting portion in the length direction; a moving portion that linearly moves along the rail portion; and a rotating shaft that is rotatably disposed on the moving portion. 8.The machine tool according to claim 7, wherein the operation portion comprises: a first operation portion that is disposed on the mounting portion for linearly moving the moving portion; and a second operation portion that is disposed on the moving portion for rotating the rotating shaft. 9.The machine tool according to claim 2, wherein the optional portion further comprises a bucket portion that is disposed at a front end of the shaft portion and pivots in the width direction as the shaft portion rotates to discharge the workpiece clamped on the main shaft and processed to an outside of the machine tool. ​ One of the support portion or the tub portion is selectively coupled to a front end of the shaft portion, or the support portion and the tub portion are coupled together.

10. The machine tool according to claim 1, wherein A tailstock is further included, which is disposed opposite to and spaced apart from the main shaft, for supporting a free end of a workpiece clamped to the main shaft.

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