Machine tool

Abstract

To provide a machine tool that is used for friction pressure welding members to each other, which can be elongated in service life.SOLUTION: A machine tool 100 comprises: a first spindle 110 that rotates while gripping a first member B1 that can move in an axial direction; a second spindle 210 that rotates while gripping a second member B2 that can move in the axial direction; a first moving mechanism 160 that moves the first spindle 110 in the axial direction; a second moving mechanism 260 that moves the second spindle 210 in the axial direction; and a control device 180 that controls the first spindle 110, the second spindle 210, the first moving mechanism 160 and the second moving mechanism 260. The control device 180 is configured to friction pressure weld the first member B1 to the second member B2 and also is configured to make a position in the axial direction of at least either of the first spindle 110 and the second spindle 210 at the time when performing friction pressure welding this time, different from a position in the axial direction thereof at the time when friction pressure welding has been performed last time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to machine tools. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known a machine tool that moves a spindle in an axial direction by utilizing a ball screw mechanism (movement mechanism) including a ball nut and a ball screw shaft (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6867957 Summary of the Invention [Problem to be solved by the invention]

[0004] This machine tool is configured to change the position of the engagement portion between the ball nut and the ball screw shaft each time a product is machined, in order to prevent uneven wear on the ball screw shaft, etc., caused by positioning the engagement portion between the ball nut and the ball screw shaft in approximately the same position each time a product is machined.

[0005] However, this machine tool is not suitable for use in friction welding of members together, and no structure has been disclosed to date for suppressing wear on the movement mechanism that may be caused by repeatedly friction welding members together in a machine tool having two opposing spindles.

[0006] It is therefore desirable to suppress wear on the moving mechanism that may be caused by repeated friction welding of parts together in a machine tool having two opposing spindles, and ultimately to extend the life of the machine tool including the moving mechanism. [Means for solving the problem]

[0007] A machine tool according to an embodiment of the present disclosure is a machine tool having a first spindle that rotates while gripping a first member movable in an axial direction, a second spindle that rotates while gripping a second member movable in the axial direction, a first moving mechanism that moves the first spindle in the axial direction, a second moving mechanism that moves the second spindle in the axial direction, and a control device that controls the first spindle, the second spindle, the first moving mechanism, and the second moving mechanism, wherein the control device is configured to operate the first spindle, the second spindle, the first moving mechanism, and the second moving mechanism to cause the first member and the second member to rotate relative to each other while in contact with each other and to heat them by friction, and to bring the first spindle and the second spindle closer to each other relatively in the axial direction while the relative rotation is stopped, thereby friction welding the first member and the second member, and is configured to make the axial position of at least one of the first spindle and the second spindle when performing this friction welding different from that when performing the previous friction welding. Effect of the Invention

[0008] The above-described configuration can suppress wear on the moving mechanism and realize a longer service life for the machine tool. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an example configuration of a machine tool according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a perspective view of a portion of the machine tool of FIG. 1. [Diagram 3] FIG. 2 is a side view of a main part of the machine tool of FIG. [Figure 4] 3 is a flowchart showing an example of a flow of a friction welding process. [Diagram 5] FIG. 4 is a diagram showing an example of the movement of a spindle during friction welding processing. [Figure 6] 11 is a flowchart showing an example of the flow of a position adjustment process. [Figure 7] A side view of the main parts of the machine tool when the upsetting process is started. [Figure 8]A side view of the main parts of the machine tool when the upsetting process is started. [Figure 9] FIG. 11 is a schematic diagram showing another configuration example of a machine tool according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Various embodiments of the present disclosure will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a configuration example of a machine tool 100 according to an embodiment of the present disclosure. The machine tool 100 is a moving-spindle type lathe (Swiss-type lathe), and is mainly equipped with a first spindle 110, a second spindle 210, and a tool rest 130A. FIG. 2 is a perspective view of a part of the machine tool 100 (a part including the first spindle 110). The first spindle 110 is also called the "front spindle," and the second spindle 210 is also called the "back spindle."

[0011] A first spindle chuck 120 is provided at the tip of the first spindle 110, and a second spindle chuck 220 is provided at the tip of the second spindle 210. The first spindle 110 is configured to grip the first member B1 by closing the first spindle chuck 120, and to release the first member B1 by opening the first spindle chuck 120. The first spindle 110 is supported by a first spindle stock 110A so as to be rotated by the power of a first spindle motor (not shown). Similarly, the second spindle 210 is configured to grip the second member B2 by closing the second spindle chuck 220, and to release the second member B2 by opening the second spindle chuck 220. The second spindle 210 is supported by a second spindle stock 210A so as to be rotated by the power of a second spindle motor (not shown). The first spindle motor is, for example, a built-in motor disposed between the first spindle stock 110A and the first spindle 110. The same applies to the second spindle motor.

[0012] The first member B1 and the second member B2 are elongated cylindrical members made of metal, non-ferrous metal, resin, etc. The first member B1 and the second member B2 may be members made of the same type of material, or may be members made of different types of materials.

[0013] 1 and 2, the first headstock 110A is movable in the Z-axis direction, which is the axial direction of the first spindle 110, by a first moving mechanism 160 serving as a Z-axis feed mechanism. The first spindle 110 moves in the Z-axis direction as the first moving mechanism 160 moves the first headstock 110A in the Z-axis direction.

[0014] 1, the second headstock 210A is movable in the Z-axis direction, which is the axial direction of the second spindle 210, by a second moving mechanism 260 serving as a Z-axis direction feed mechanism. The second spindle 210 moves in the Z-axis direction as the second moving mechanism 260 moves the second headstock 210A in the Z-axis direction.

[0015] The first moving mechanism 160 includes a first base 161, a first guide rail 162, a first feed table 163, and a first guide block 164. The first guide rail 162 is provided on the upper surface of the first base 161 so as to extend in the Z-axis direction. In the illustrated example, the first guide rail 162 is configured with a pair of guide rails arranged at an interval in the Y-axis direction. The first guide block 164 is provided slidably on the first guide rail 162. In the illustrated example, the first guide block 164 includes four guide blocks. That is, two guide blocks are arranged on one guide rail at an interval in the Z-axis direction.

[0016] The first guide rail 162 and the first guide block 164 constitute a first sliding guide means that guides the sliding of the first spindle 110 in the Z-axis direction relative to the first base 161. In the illustrated example, the first sliding guide means is a circulating ball type first linear guide LG1.

[0017] The first feed table 163 is a member that is fastened to the first guide block 164. In the illustrated example, the first feed table 163 includes a rectangular base, and the four corners of the base are fastened to the four guide blocks. In addition, the first headstock 110A is mounted on the first feed table 163.

[0018] The first ball screw mechanism 165 is an example of a first driving means that drives the movement of the first spindle 110 in the Z-axis direction. In the illustrated example, the first ball screw mechanism 165 includes a first ball nut 165a, a first ball screw shaft 165b, and a first servo motor 165c. The first servo motor 165c is an example of a motor that rotationally drives the first ball screw shaft 165b.

[0019] The first ball nut 165a is fixed to the lower part of the first feed table 163. The first ball screw shaft 165b and the first servo motor 165c are fixed to the upper part of the first base 161. The first ball screw shaft 165b is rotated by driving the first servo motor 165c. When the first ball screw shaft 165b rotates, the first ball nut 165a moves in the Z-axis direction along the first ball screw shaft 165b. When the first ball nut 165a moves in the Z-axis direction, the first feed table 163 moves in the Z-axis direction together with the first ball nut 165a. Since the first headstock 110A is fixed to the first feed table 163, it moves in the Z-axis direction together with the first feed table 163. The same applies to the first spindle 110 rotatably supported by the first headstock 110A.

[0020] The first driving means and the first sliding guide means each include an engaging means whose engaging position changes with the movement of the first main shaft 110 in the Z-axis direction. The first ball screw mechanism 165 serving as the first driving means changes the engaging position between the first ball nut 165a serving as the engaging means and the first ball screw shaft 165b with the movement of the first main shaft 110 in the Z-axis direction. Also, the first linear guide LG1 serving as the first sliding guide means changes the engaging position between the first guide rail 162 serving as the engaging means and the first guide block 164 with the movement of the first main shaft 110 in the Z-axis direction.

[0021] The second moving mechanism 260 has a similar configuration to the first moving mechanism 160. The second base 261, the second feed table 263, the second linear guide LG2 (the second guide rail 262 and the second guide block 264), and the second ball screw mechanism 265 (the second ball nut 265a, the second ball screw shaft 265b, and the second servo motor 265c) of the second moving mechanism 260 correspond to the first base 161, the first feed table 163, the first linear guide LG1 (the first guide rail 162 and the first guide block 164), and the first ball screw mechanism 165 (the first ball nut 165a, the first ball screw shaft 165b, and the first servo motor 165c) of the first moving mechanism 160, respectively.

[0022] A pedestal 168 is integrally provided on the first base 161. The pedestal 168 is configured to be able to move the tool rest 130A in both the X-axis direction (up-down direction) and the Y-axis direction (left-right direction). A cutting tool 130 such as a cutting tool for turning the first member B1 is attached to the tool rest 130A.

[0023] The tool rest 130A is provided on the base 168 via an X-axis direction feed mechanism 150 and a Y-axis direction feed mechanism 170 so as to be movable in the X-axis direction and the Y-axis direction relative to the first spindle 110. In other words, the X-axis direction feed mechanism 150 and the Y-axis direction feed mechanism 170 constitute a tool rest movement mechanism that moves the tool rest 130A in the X-axis direction and the Y-axis direction relative to the first spindle 110.

[0024] The X-axis feed mechanism 150 includes an X-axis guide rail 152, an X-axis feed table 153, and an X-axis guide block 154. The X-axis guide rail 152 is a guide rail extending in the X-axis direction provided on a Y-axis feed table 173 located on the fixed side of the X-axis feed mechanism 150. The X-axis guide block 154 is attached to the X-axis guide rail 152 so as to be slidable in the X-axis direction along the X-axis guide rail 152. The X-axis feed table 153 is fixed to the X-axis guide block 154 and configured to be movable in the X-axis direction together with the X-axis guide block 154.

[0025] The X-axis ball screw mechanism 155 is an example of a drive means that drives the movement in the X-axis direction of the X-axis feed table 153. In the illustrated example, the X-axis ball screw mechanism 155 includes a ball nut 155a, a ball screw shaft 155b, and a servo motor 155c. The servo motor 155c is an example of a motor that rotates and drives the ball screw shaft 155b.

[0026] The ball nut 155a is fixed to the X-axis direction feed table 153. The ball screw shaft 155b and the servo motor 155c are fixed to the Y-axis direction feed table 173. The ball screw shaft 155b is rotated by the drive of the servo motor 155c. When the ball screw shaft 155b rotates, the ball nut 155a moves in the X-axis direction along the ball screw shaft 155b. When the ball nut 155a moves in the X-axis direction, the X-axis direction feed table 153 moves in the X-axis direction together with the ball nut 155a. Since the tool rest 130A is fixed to the X-axis direction feed table 153, it moves in the X-axis direction together with the X-axis direction feed table 153. The same applies to the cutting tool 130 supported by the tool rest 130A.

[0027] The Y-axis direction feed mechanism 170 includes a Y-axis direction guide rail 172, a Y-axis direction feed table 173, and a Y-axis direction guide block 174. The Y-axis direction guide rail 172 is a guide rail extending in the Y-axis direction provided on a pedestal 168 located on the fixed side of the Y-axis direction feed mechanism 170. The Y-axis direction guide block 174 is attached to the Y-axis direction guide rail 172 so as to be slidable in the Y-axis direction along the Y-axis direction guide rail 172. The Y-axis direction feed table 173 is fixed to the Y-axis direction guide block 174 and configured to be movable in the Y-axis direction together with the Y-axis direction guide block 174.

[0028] Although not shown, the Y-axis ball screw mechanism is an example of a driving means that drives the movement of the Y-axis feed table 173 in the Y-axis direction, and has a similar configuration to the X-axis ball screw mechanism 155.

[0029] With this configuration, the tool rest 130A moves in the X-axis direction by the movement of the X-axis direction feed table 153, and moves in the Y-axis direction by the movement of the Y-axis direction feed table 173. The cutting tool 130 attached to the tool rest 130A moves in the X-axis direction and the Y-axis direction together with the tool rest 130A. The first member B1 is cut into a product of any shape by the cutting tool 130 moving in the X-axis direction and the Y-axis direction. When cutting a product of a predetermined shape, the first headstock 110A moves in the Z-axis direction as the machining of the product progresses.

[0030] In the illustrated example, the rotating means for relatively rotating the first member B1 and the cutting tool 130 is configured by a first spindle motor such as a built-in motor, but other configurations may be adopted.

[0031] In addition, in the illustrated example, the machine tool 100 is configured to rotate the first member B1 relative to the cutting tool 130, but may be configured to rotate the cutting tool 130 relative to the first member B1. In this case, the cutting tool 130 may be, for example, a rotating tool such as a drill.

[0032] In addition, in the illustrated example, the X-axis feed mechanism 150 is mounted on the base 168 via the Y-axis feed mechanism 170, and the tool rest 130A is mounted on the X-axis feed table 153 of the X-axis feed mechanism 150, but the Y-axis feed mechanism 170 may be mounted on the base 168 side via the X-axis feed mechanism 150, and the tool rest 130A may be mounted on the Y-axis feed table 173 of the Y-axis feed mechanism 170.

[0033] In the illustrated example, the X-axis direction feed mechanism 150, the Y-axis direction feed mechanism 170, and the Z-axis direction feed mechanism (first moving mechanism 160) are ball screw mechanisms, but may be other mechanisms such as linear servo motors.

[0034] Furthermore, the machine tool 100 may be provided with a tool rest for cutting the second member B2 gripped by the second spindle chuck 220, separate from the tool rest 130A. In this case, the second spindle rest 210A may be configured to be movable not only in the Z-axis direction but also in the Y-axis direction. Furthermore, the machine tool 100 may be provided with a spindle (clamp device) separate from the second spindle 210, which grips the second member B2 when joining the first member B1 and the second member B2.

[0035] Control device 180 is a device for controlling the movement of machine tool 100. In the illustrated example, control device 180 is a computer including a CPU, a volatile storage device, a non-volatile storage device, an input / output interface, and the like.

[0036] The control device 180 has a control unit 181 that controls the movement of the machine tool 100. The control unit 181 is configured to be able to control the rotation of the first spindle 110, the rotation of the second spindle 210, the movement of the first spindle stock 110A in the Z-axis direction by the first moving mechanism 160, the movement of the second spindle stock 210A in the Z-axis direction by the second moving mechanism 260, the movement of the X-axis feed table 153 in the X-axis direction by the X-axis feed mechanism 150, and the movement of the Y-axis feed table 173 in the Y-axis direction by the Y-axis feed mechanism 170. In the illustrated example, the control unit 181 is configured with software. However, the control unit 181 may be configured with hardware, or may be configured with a combination of software and hardware.

[0037] In the illustrated example, the machine tool 100 is configured to operate in conjunction with a material feeder 190 that supplies a first member B1 to the first spindle 110. However, the material feeder 190 may be a part of the machine tool 100. The machine tool 100 may be configured to operate in conjunction with a material feeder (not shown) that supplies a second member B2 to the second spindle 210. In this case, the material feeder that supplies the second member B2 to the second spindle 210 may be a part of the machine tool 100.

[0038] Next, an example of friction welding will be described with reference to FIG. 3, FIG. 4, and FIG. 5. FIG. 3 is a side view of the main part of the machine tool 100. The main part of the machine tool 100 includes the first spindle 110, the first spindle stock 110A, the first spindle chuck 120, the first moving mechanism 160, the first feed table 163, the second spindle 210, the second spindle stock 210A, the second spindle chuck 220, the second moving mechanism 260, the second feed table 263, the first linear guide LG1, and the second linear guide LG2. FIG. 4 is a flow chart showing an example of the flow of friction welding performed by the machine tool 100. The friction welding is a process in which the contact part is softened by frictional heat generated when two members are rubbed together, and an upset pressure is applied to the contact part to join the two members. Friction welding is one of the solid-phase joining methods in which joining is performed at a temperature below the melting point of each member, and is also called "friction joining". Fig. 5 is a cross-sectional view of the first spindle chuck 120 gripping the first member B1 and the second spindle chuck 220 gripping the second member B2, showing an example of the movement of the spindle during friction welding. In Fig. 5, for clarity, the cross sections of the first member B1 and the second member B2 are hatched with oblique lines, but the hatching of the cross sections of the first spindle chuck 120 and the second spindle chuck 220 is omitted. The friction welding process described with reference to Figs. 4 and 5 is realized by the operation of each element of the machine tool 100 in response to a command from the control device 180.

[0039] First, the control device 180 arranges the first member B1 and the second member B2 to face each other (step ST1). The control device 180 arranges the first member B1 and the second member B2 to face each other such that the left end of the first member B1 held by the first spindle chuck 120 and the right end of the second member B2 held by the second spindle chuck 220 face each other across a predetermined distance DS, as shown in FIG. 5(a).

[0040] 3 shows a state of the main part of the machine tool 100 when the first member B1 and the second member B2 are disposed facing each other with a predetermined distance DS therebetween. FIG. 3 shows a state in which the protrusion amount P1 of the first member B1 and the protrusion amount P2 of the second member B2 are substantially the same. The protrusion amount P1 of the first member B1 is the distance between the tip (left end) of the first member B1 held by the first spindle chuck 120 and the tip (left end) of the first spindle chuck 120, and corresponds to the protrusion amount of the first member B1 relative to the first spindle chuck 120. Similarly, the protrusion amount P2 of the second member B2 is the distance between the tip (right end) of the second member B2 held by the second spindle chuck 220 and the tip (right end) of the first spindle chuck 120, and corresponds to the protrusion amount of the second member B2 relative to the second spindle chuck 220. 3 also shows that the distance between the first ball nut 165a and the first servo motor 165c is distance D1, and the distance between the second ball nut 265a and the first servo motor 165c is distance D2. Note that distance D1 is an example of a value representing the engagement position between the first ball nut 165a and the first ball screw shaft 165b, and the engagement position between the first ball nut 165a and the first ball screw shaft 165b may be represented by another value. The same applies to distance D2.

[0041] Thereafter, the control device 180 starts rotating the first member B1 (step ST2). FIG. 5(b) shows a state in which the first member B1 is rotating at a predetermined rotation speed RF. The control device 180 may rotate the second member B2 instead of the first member B1, or may rotate both the first member B1 and the second member B2. When rotating both the first member B1 and the second member B2, the rotation directions may be the same or opposite to each other.

[0042] Thereafter, the control device 180 starts contact between the first member B1 and the second member B2 (step ST3). As shown in Fig. 5(c), the control device 180 moves the second member B2 rightward at a speed faster than the speed at which the first member B1 moves rightward, thereby bringing the right end of the second member B2 into contact with the left end of the first member B1. The rightward direction corresponds to the direction from the second spindle chuck 220 to the first spindle chuck 120.

[0043] The control device 180 moves the first spindle chuck 120 (first spindle stock 110A) rightward so that the first member B1 moves rightward at a predetermined moving speed M1. Furthermore, the control device 180 moves the second spindle chuck 220 (second spindle stock 210A) rightward so that the second member B2 moves rightward at a predetermined moving speed M2 that is higher than the moving speed M1. Therefore, the second member B2 comes into contact with the first member B1 at a predetermined timing, and a frictional thrust is applied to the contact surface (joint surface CS) between the first member B1 and the second member B2. The moving speed M1 may be zero.

[0044] Thereafter, the first member B1 continues to move rightward at a moving speed M1 while rotating at a rotation speed RF, and the second member B2 continues to move rightward in the same direction as the first member B1 at a moving speed M2. Therefore, the temperature of the joint surface CS between the first member B1 and the second member B2 increases due to frictional heat generated by the rotation of the first member B1. At least one of the moving speed M1 and the moving speed M2 may be variable.

[0045] Thereafter, when a predetermined condition is satisfied, the control device 180 stops the rotation of the first member B1 (step ST4). The predetermined condition is, for example, the passage of a predetermined time. The predetermined time is, for example, the time required for the joining surface CS to reach a predetermined temperature due to frictional heat. FIG. 5(d) shows the state when the rotation of the first member B1 is stopped. The predetermined condition may be that the first spindle chuck 120 (first spindle stock 110A) has moved a predetermined distance to the right, or that the second spindle chuck 220 (second spindle stock 210A) has moved a predetermined distance to the right, or the like.

[0046] Thereafter, the control device 180 starts applying the upset thrust (step ST5). The control device 180 moves the second member B2 in a direction (rightward) from the second spindle chuck 220 to the first spindle chuck 120. The control device 180 moves the second member B2 rightward at a moving speed V. Therefore, the control device 180 can apply the upset thrust to the joint surface CS between the first member B1 and the second member B2. The magnitude of the upset thrust is larger as the moving speed V is higher. The moving speed V may be variable. FIG. 5(e) shows a state when the second member B2 is moving rightward. This process of step ST5 is also called an "upset process". During the upset process, the control device 180 may move the first member B1 rightward at a moving speed lower than the moving speed V.

[0047] Thereafter, after the upset thrust is applied to the joining surface CS for a predetermined upset time, the control device 180 stops the application of the upset thrust (step ST6). The control device 180 stops the application of the upset thrust by stopping the movement of the second spindle chuck 220. FIG. 5(f) shows the state when the application of the upset thrust is stopped. FIG. 5(f) also shows that burrs FS are generated around the joining surface CS due to friction welding. The first member B1 and the second member B2 are joined by friction welding to form a joining member WC.

[0048] Thereafter, the control device 180 removes the burr FS (step ST7). As shown in Fig. 5(f), the control device 180 operates the tool rest 130A to bring the tip of the cutting tool 130 into contact with the portion of the joined member WC where the burr FS is formed, and cuts off the burr FS. This is to prevent the burr FS from interfering with the first spindle chuck 120 when the joined member WC is pulled back. Fig. 5(g) shows the state after the burr FS has been removed.

[0049] Thereafter, the control device 180 pulls back the joint member WC (step ST8). The control device 180 moves the first spindle chuck 120 gripping the first member B1 of the joint member WC to the right, thereby removing the joint member WC from the second spindle chuck 220 gripping the second member B2 of the joint member WC. At this time, the control device 180 opens the second spindle chuck 220 and releases the grip of the second member B2 of the joint member WC.

[0050] In this way, the control device 180 can repeatedly perform the joining of the first member B1 and the second member B2 by friction welding. However, if the axial positions of the two spindles (the first spindle 110 and the second spindle 210) do not change each time when the joining of the first member B1 and the second member B2 is repeatedly performed in the machine tool 100, a load is concentrated on a specific portion such as the ball screw shaft or the ball nut. For this reason, there is a risk that wear will occur locally on the ball screw shaft or the guide rail. As the wear progresses, a backlash occurs, the positioning accuracy deteriorates, and finally, the ball screw shaft or the guide rail or the like needs to be replaced. The axial position of the spindle means the position of the spindle in a direction parallel to the axis of the spindle. Specifically, the position of the spindle is, for example, the tip position of the spindle chuck, the tip position of the spindle stock, or the rear end position of the spindle stock. In addition, the specific portion may be, for example, a portion on the ball screw shaft where the ball nut is engaged, or a portion on the guide rail where the guide block is engaged, or the like.

[0051] Therefore, the machine tool 100 of the present disclosure is configured to perform a position adjustment process to prevent the axial positions of the two spindles from being the same every time and to prevent local wear from occurring on the ball screw shaft, guide rail, etc. The position adjustment process is a process for changing the position of at least one of the two spindles so that the position of at least one of the two spindles when friction welding is performed is different from the position when the previous friction welding was performed.

[0052] Next, an example of the position adjustment process will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a flow chart showing an example of the flow of the position adjustment process executed by the machine tool 100. Fig. 7 is a side view of the main parts of the machine tool 100 when the upset process before last was started, Fig. 7(b) is a side view of the main parts of the machine tool 100 when the previous upset process was started, and Fig. 7(c) is a side view of the main parts of the machine tool 100 when the current upset process was started. The position adjustment process described with reference to Figs. 6 and 7 is realized by the operation of each element of the machine tool 100 in response to a command from the control device 180.

[0053] In the illustrated example, the control device 180 of the machine tool 100 is configured to execute the position adjustment process immediately before executing each friction welding process. However, the control device 180 may be configured to execute the position adjustment process at any timing.

[0054] First, the control device 180 determines the axial positions of the two spindles (the first spindle 110 and the second spindle 210) (step ST21).

[0055] In the illustrated example, the control device 180 is configured to detect the current axial positions of the two spindles based on the outputs of various sensors. The various sensors are, for example, an encoder for detecting the number of revolutions of a ball screw shaft, or a sensor for detecting the amount of movement of a linear guide. The control device 180 also stores the set movement amount of each of the two spindles to be moved in each position adjustment process in a non-volatile storage device. The control device 180 then determines the axial positions of each of the two spindles when the current friction welding process is started based on, for example, the axial positions of each of the two spindles when the previous friction welding process is started and the set movement amounts of each of the two spindles. However, the control device 180 may determine the axial positions of each of the two spindles when the current friction welding process is started based on any other method.

[0056] Thereafter, the control device 180 moves at least one of the two spindles in the axial direction (step ST22). In the illustrated example, the control device 180 moves at least one of the two spindles in the axial direction until each of the two spindles reaches the axial position determined in step ST21.

[0057] As shown in FIG. 7, the movement of the two spindles is performed in a manner such that neither the projection amount P1 of the first member B1 nor the projection amount P2 of the second member B2 changes.

[0058] The control device 180 moves the first spindle 110 by the first ball screw mechanism 165 so that the distance D13 (see FIG. 7(c)) between the first ball nut 165a and the first servo motor 165c when the current upset process is started is different from the distance D11 (see FIG. 7(a)) between the first ball nut 165a and the first servo motor 165c when the upset process before last was started, and the distance D12 (see FIG. 7(b)) between the first ball nut 165a and the first servo motor 165c when the previous upset process was started. Note that the distances D11, D12, and D13 are examples of the distance D1. The same is true for the distance D2 (distances D21, D22, and D23).

[0059] With this configuration, the control device 180 can prevent the load from concentrating on a specific portion each time friction welding is performed.

[0060] Next, another example of the position adjustment process will be described with reference to Fig. 8. Fig. 8 is a side view of the main parts of the machine tool 100 when the upset process is started, and corresponds to Figs. 3 and 7. Fig. 8(a) is a side view of the main parts of the machine tool 100 when the upset process before last is started, Fig. 8(b) is a side view of the main parts of the machine tool 100 when the previous upset process is started, and Fig. 8(c) is a side view of the main parts of the machine tool 100 when the current upset process is started. Note that the position adjustment process described with reference to Fig. 8 is realized by the operation of each element of the machine tool 100 in response to a command from the control device 180, similar to the case of the position adjustment process described with reference to Fig. 7.

[0061] The position adjustment process described with reference to Figure 8 differs from the position adjustment process described with reference to Figure 7 mainly in that at least one of the extension amount P1 of the first member B1 and the extension amount P2 of the second member B2 when the friction welding process is performed is made different from when the previous friction welding process was performed.

[0062] In the illustrated example, the control device 180 moves the first spindle 110 by the first ball screw mechanism 165 so that the protrusion amount P13 (see FIG. 8(c)) of the first member B1 when the current upsetting process is started is different from the protrusion amount P11 (see FIG. 8(a)) of the first member B1 when the upsetting process before last was started and the protrusion amount P12 (see FIG. 8(b)) of the first member B1 when the previous upsetting process was started. In the illustrated example, the protrusion amount P12 (see FIG. 8(b)) is larger than the protrusion amount P11 (see FIG. 8(a)) by d1, and the protrusion amount P13 (see FIG. 8(c)) is larger than the protrusion amount P12 (see FIG. 8(b)) by d2. Furthermore, the control device 180 moves the first spindle 110 by the first ball screw mechanism 165 so that the distance D13 (see FIG. 8(c)) between the first ball nut 165a and the first servo motor 165c when the current upset process is started is different from the distance D11 (see FIG. 8(a)) between the first ball nut 165a and the first servo motor 165c when the upset process before last was started, and the distance D12 (see FIG. 8(b)) between the first ball nut 165a and the first servo motor 165c when the previous upset process was started. In the illustrated example, the distance D12 (see FIG. 8(b)) is shorter than the distance D11 (see FIG. 8(a)) by d1, and the distance D13 (see FIG. 8(c)) is shorter than the distance D12 (see FIG. 8(b)) by d2. That is, the difference between the distance D11 and the distance D12 is equal to the difference between the projection amount P11 and the projection amount P12, and the difference between the distance D12 and the distance D13 is equal to the difference between the projection amount P12 and the projection amount P13. Therefore, the position of the tip (left end) of the first member B1 in the axial direction does not change, and the position of the joint surface CS in the axial direction does not change either.

[0063] On the other hand, the movement of the two spindles is performed in such a manner that the distance D2 between the second ball nut 265a and the second servo motor 265c does not change, as shown in Fig. 8. In other words, the movement is performed in such a manner that only the axial position of the first spindle 110 changes.

[0064] The control device 180 moves the first spindle 110 by the first ball screw mechanism 165 so that a distance D13 (see FIG. 8(c)) when the current upset process is started is different from both the distance D11 (see FIG. 8(a)) when the upset process before last was started and the distance D12 (see FIG. 8(b)) when the previous upset process was started. On the other hand, the control device 180 does not move the second spindle 210 by the second ball screw mechanism 265.

[0065] In addition, the control device 180 causes the material feeder 190 to protrude the first member B1 to the left so that the protrusion amount P13 (see FIG. 8(c)) of the first member B1 when the current upset process is started is different from the protrusion amount P11 (see FIG. 8(a)) of the first member B1 when the upset process before last was started, and the protrusion amount P12 (see FIG. 8(b)) of the first member B1 when the previous upset process was started. This is to ensure that the position of the joining surface CS is the same when each upset process is started.

[0066] In the example shown in FIG. 8, the position adjustment process is realized by moving the first spindle 110 without moving the second spindle 210, but may be realized by moving the second spindle 210 without moving the first spindle 110. That is, in the example shown in FIG. 8, the position adjustment process is realized by changing the extension amount P1 of the first member B1 without changing the extension amount P2 of the second member B2, but may be realized by changing the extension amount P2 of the second member B2 without changing the extension amount P1 of the first member B1. Alternatively, the position adjustment process may be realized by changing both the extension amount P1 and the extension amount P2. In addition, the position adjustment process may be realized by combining the example shown in FIG. 7 and the example shown in FIG. 8. That is, the control device 180 may execute the position adjustment process by changing both the distance D1 and the distance D2 and by changing at least one of the extension amount P1 and the extension amount P2.

[0067] With this configuration, the control device 180 can prevent the load from concentrating on a specific portion each time a friction welding process is performed. In the example shown in Fig. 8, the control device 180 is configured to change the axial position of one of the two spindles before each friction welding process, but it may also be configured to change the axial position of one of the two spindles each time multiple friction welding processes are performed. In other words, multiple consecutive friction welding processes may be performed in a manner in which the axial positions of both of the two spindles are the same.

[0068] Next, another configuration example of the machine tool 100 of the present disclosure will be described with reference to Fig. 9. Fig. 9 is a schematic diagram of another configuration example of the machine tool 100 of the present disclosure. The machine tool 100 shown in Fig. 9 differs from the machine tool 100 shown in Fig. 1 in that it includes a guide bush 140, but is the same as the machine tool 100 in other respects. Therefore, in the following, a description of the common parts will be omitted and the different parts will be described in detail.

[0069] The guide bush 140 is a member provided on the base 168, and is configured to guide the first member B1 fed in the Z-axis direction from the first spindle 110. Therefore, the first member B1 advancing to the left is cut by the cutting tool 130 while being guided in the Z-axis direction by the guide bush 140 provided in front of the cutting tool 130, to become a product.

[0070] 1, this configuration provides the advantage that the protrusion amount P1 of the first member B1 can be changed more flexibly without excessively affecting the quality of the joined member WC produced by friction welding. This is because the tip (left end) of the first member B1 is guided by the guide bush 140. As a result, this configuration provides the advantage that the axial position of the first spindle 110 when friction welding is performed can be determined more flexibly than the machine tool 100 shown in FIG.

[0071] With the above-mentioned configuration, machine tool 100 can prevent a particular portion, such as a portion on a ball screw shaft where a ball nut is engaged or a portion on a guide rail where a guide block is engaged, from always being in the same position during friction welding, and can prevent a load from concentrating at the same position. In other words, machine tool 100 can distribute the positions to which the load is applied. Therefore, machine tool 100 can extend the life of components such as a ball screw shaft or a guide rail, and ultimately extend the life of machine tool 100 itself.

[0072] Furthermore, the axial position may be, for example, the position when relative rotation between the first member B1 and the second member B2 is started (see FIG. 5(b)), the position when the first member B1 and the second member B2 are brought into contact (see FIG. 5(c)), the position when the relative rotation is stopped (see FIG. 5(d)), the position when the upset process is started (see FIG. 5(e)), or the position when friction welding is completed (see FIG. 5(f)).

[0073] This configuration, which enables accurate specification of the axial positions of the first main shaft 110 and the second main shaft 210 when performing friction welding of the first member B1 and the second member B2, has the effect of enabling accurate specification of the position of a specific portion on which a load related to friction welding acts.

[0074] In addition, the axial position may be, for example, a position when relative rotation between the first member B1 and the second member B2 is started (see FIG. 5(b)), a position when the first member B1 and the second member B2 are brought into contact (see FIG. 5(c)), a position when the relative rotation is stopped (see FIG. 5(d)), a position when the upset process is started (see FIG. 5(e)), and a position when friction welding is completed (see FIG. 5(f)), or a position within a range between these two positions.

[0075] This configuration, which makes it possible to specify a range of the axial positions of the first main shaft 110 and the second main shaft 210 when performing friction welding of the first member B1 and the second member B2, has the effect of making it possible to specify a range of the position of a specific portion on which the load related to friction welding acts.

[0076] Furthermore, the position of the joining surface CS between the first member B1 and the second member B2 when the current friction welding is performed may be the same as when the previous friction welding was performed.

[0077] This configuration has the effect of, for example, enabling the position of the joint surface CS when each friction welding process is completed to be located directly below the cutting tool 130, thereby making it possible to efficiently remove burrs FS formed around the joint surface CS during each friction welding process.

[0078] Furthermore, machine tool 100 can prevent the position of the portion on first guide rail 162 where first guide block 164 engages and the position of the portion on second guide rail 262 where second guide block 264 engages from always being in the same position during friction welding, which would cause load concentration at the same position. In other words, this configuration can distribute the positions to which the load is applied. Therefore, this configuration can extend the life of first guide rail 162 and second guide rail 262, and ultimately the life of machine tool 100.

[0079] The preferred embodiments of the present disclosure have been described above in detail. However, the present invention is not limited to the above-described embodiments. Various modifications or substitutions may be applied to the above-described embodiments without departing from the scope of the present invention. Furthermore, each of the features described with reference to the above-described embodiments may be appropriately combined as long as there is no technical contradiction.

[0080] For example, the control device 180 may store data on the axial positions of the two spindles when each friction welding process is started in a non-volatile storage device. In this case, the control device 180 may determine the axial positions of the two spindles when the current friction welding process is started so that the axial positions of the two spindles when the current friction welding process is started are different from the axial positions of the two spindles when each previous friction welding process is started. Alternatively, the control device 180 may determine the axial positions of the two spindles when the current friction welding process is started so that the axial positions of the two spindles when the current friction welding process is started are axial positions that are used relatively infrequently. Alternatively, the control device 180 may determine the axial positions of the two spindles when each friction welding process is started so that the axial positions of the two spindles when the current friction welding process is started are different from the axial positions during product processing.

[0081] In the above embodiment, the control device 180 is configured to change the axial position of each of the two spindles before each friction welding process, but may be configured to change the axial position of at least one of the two spindles every time multiple friction welding processes are performed. That is, multiple consecutive friction welding processes may be performed in such a manner that the axial position of at least one of the two spindles is the same.

[0082] In addition, in the example shown in FIG. 7, the control device 180 performs the position adjustment process by moving the first spindle 110 backward (to the right) and moving the second spindle 210 forward (to the right), but the position adjustment process may also be performed by moving the first spindle 110 forward (to the left) and moving the second spindle 210 backward (to the left). [Explanation of symbols]

[0083] 100 machine tool 110 first spindle 110A first spindle head 120 first spindle chuck 130 cutting tool 130A tool rest 140 guide bush 150 X-axis feed mechanism 152 X-axis guide rail 153 X-axis feed table 154 X-axis guide block 155 X-axis ball screw mechanism 155a ball nut 155b ball screw shaft 155c servo motor 160 first movement mechanism 161 first base 162 first guide rail 163 first feed table 164 first guide block 165 first ball screw mechanism 165a first ball nut Description of the Reference Signs 165b...first ball screw shaft 165c...first servo motor 168...base 170...Y-axis direction feed mechanism 172...Y-axis direction guide rail 173...Y-axis direction feed table 174...Y-axis direction guide block 180...control device 181...control unit 190...material feeder 210...second spindle 210A...second spindle stock 220...second spindle chuck 260...second movement mechanism 261...second base 262...second guide rail 263...second feed table 264...second guide block 265...second ball screw mechanism 265a...second ball nut 265b...second ball screw shaft 265c...second servo motor B1...First component B2...Second component CS...Joint surface FS...Burrs LG1...First linear guide LG2...Second linear guide WC...Joining component

Claims

1. a first main shaft that rotates by gripping a first member that is movable in an axial direction; a second main shaft that rotates by gripping a second member that is movable in an axial direction; a first moving mechanism that moves the first spindle in an axial direction; a second moving mechanism that moves the second spindle in an axial direction; a control device that controls the first spindle, the second spindle, the first movement mechanism, and the second movement mechanism, The control device includes: the first main shaft, the second main shaft, the first moving mechanism, and the second moving mechanism are operated to relatively rotate the first member and the second member in a state of contact with each other to cause frictional heating, and the first main shaft and the second main shaft are brought relatively close to each other in the axial direction in a state where the relative rotation is stopped, thereby performing frictional welding of the first member and the second member, The axial position of at least one of the first spindle and the second spindle when performing the current friction welding is made different from that when performing the previous friction welding. A machine tool characterized by:

2. The control device is configured to make the axial positions of the first spindle and the second spindle when performing the current friction welding different from those when performing the previous friction welding. The machine tool according to claim 1.

3. The amount of protrusion of the first member when performing this friction welding is the same as when performing the previous friction welding. The machine tool according to claim 1.

4. The amount of protrusion of the second member when performing this friction welding is the same as when performing the previous friction welding. The machine tool according to claim 1.

5. The position of the joining surface between the first member and the second member when performing this friction welding is the same as when performing the previous friction welding. The machine tool according to claim 1.

6. the first moving mechanism is a first ball screw mechanism including a first ball screw shaft and a first ball nut, the second moving mechanism is a second ball screw mechanism including a second ball screw shaft and a second ball nut, The control device is configured to change at least one of a position of a portion of the first ball screw shaft with which the first ball nut is engaged when performing a current friction welding and a position of a portion of the second ball screw shaft with which the second ball nut is engaged when performing a current friction welding from a position when performing a previous friction welding. The machine tool according to claim 1.

7. a first linear guide including a first guide rail provided on a first base and a first guide block sliding on the first guide rail; a second linear guide including a second guide rail provided on a second base and a second guide block that slides on the second guide rail; the first spindle is rotatably supported by a first headstock fixed to the first guide block, the second spindle is rotatably supported by a second headstock fixed to the second guide block, the control device is configured to change at least one of a position of a portion of the first guide rail with which the first guide block is engaged when performing a current friction welding and a position of a portion of the second guide rail with which the second guide block is engaged when performing a current friction welding from a position when performing a previous friction welding. The machine tool according to claim 1.

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