CN118265584A - Control device and working machine having the same - Google Patents

Abstract

The control device (20) has an eccentric cutting control unit (27) for processing the eccentric body. The eccentric cutting control unit (27) rotates the spindle in cooperation with the control unit (23), and after positioning the eccentric body so that the center position is on the X-axis, the distance from the center of the base of the workpiece to the center of the eccentric body, i.e., the eccentricity, is set to R, and the rotation angle of the spindle axis around the X-axis with the center of the eccentric body as the reference is set to θ. In synchronization with the rotation of the spindle, the tool is relatively moved while being relatively moved in the Z-axis direction, so as to draw an arc trajectory set to the position X=Rcosθ in the X-axis direction and the position Y=Rsinθ in the Y-axis direction.

Description

Control device and working machine having the same

Technical Field

The present invention relates to a control device for a machine tool configured to perform turning processing on a workpiece, and more particularly to a control device for processing an eccentric body of a workpiece having an eccentric body at a position radially offset from the center of a spindle, and a machine tool having the same.

Background technique

For example, as a method for processing a workpiece having a cylindrical base and an eccentric body protruding outward from the end face of the base along the central axis of the base and arranged at a position radially offset from the central axis, a method disclosed in Patent Document 1 has been previously known.

In the processing method described in Patent Document 1, an eccentric chuck having a gripping portion for gripping a workpiece at a position radially shifted from the spindle axis is mounted on the spindle of a lathe, and the eccentric chuck grips the workpiece in such a manner that the axis of the eccentric body and the spindle axis become coaxial. In addition, the spindle is rotated in this state, and the outer periphery of the eccentric body is processed using a tool as appropriate.

In addition, Patent Document 2 discloses a method for turning an eccentric shaft of a crankshaft. In the processing method described in Patent Document 2, the crankshaft is rotated in a state where one end of the crankshaft is gripped by the main shaft and the other end is supported by the tailstock shaft, and the radius of the eccentric shaft is set to r, and the tool is fed and moved in the vertical direction (Y-axis direction) and the front-back direction (Z-axis direction) with a stroke of 2r in synchronization with the rotation cycle of the crankshaft. The tool performs a circular motion of a radius r by the combined feed of the feed in the Y-axis direction and the feed in the Z-axis direction, thereby turning the outer periphery of the eccentric shaft.

The same processing method is also proposed in Patent Document 3. The processing method described in Patent Document 3 processes two eccentric shafts, namely, a first eccentric shaft protruding outward from the end surface of the base along the central axis of the base and a second eccentric shaft protruding further outward from the first eccentric shaft.

Patent Document 1: Japanese Patent Application Publication No. 2003-236701

Patent Document 2: Japanese Patent Application Laid-Open No. 54-94185

Patent Document 3: Japanese Patent Application Publication No. 2017-209779

Summary of the invention

In addition, the methods disclosed in the above-mentioned patent documents 1 to 3 do not take into account the position of the eccentric body when the spindle holds the workpiece, and the angular position (phase) of the eccentric body in the circumferential direction with the axis of the spindle as the center. Therefore, in these methods, it is considered necessary to start the processing of the workpiece while holding the workpiece on the spindle so that the phase of the eccentric body becomes a predetermined reference phase.

In addition, depending on the relationship between other processing parts other than the eccentric body, the phase of the eccentric body when the workpiece is held on the spindle may differ from workpiece to workpiece. In this case, the phase of the eccentric body when the workpiece is held on the spindle cannot be set as the reference phase. Therefore, in the case of the workpiece as described above, it is convenient to start processing the eccentric body in different phases.

In addition, as a processed product with an eccentric body, the above-mentioned crankshaft and eccentric pin are exemplified. In addition, as a processed product with an eccentric body, there are various shapes such as an eccentric screw used in a force multiplier that obtains a large clamping force through a small tightening torque due to the wedge effect, and a single-axis eccentric screw used in a rotary positive displacement single-axis eccentric screw pump that can quantitatively and pulsation-free transfer of various liquids, from water-like liquids to high-viscosity liquids, solids, and powders. Therefore, if a special dedicated working machine and a dedicated chuck do not use eccentric bodies of various shapes as described above, but can be processed using a general-purpose working machine and a general-purpose chuck, it is advantageous in terms of equipment cost.

In addition, in the above-mentioned processing method, circular motion is achieved by operating the feed shaft at a high speed in synchronization with the rotation speed of the spindle, so there is a problem that the load on the feed motor is increased. Therefore, if the rotation speed of the spindle motor is controlled so that the load acting on the feed motor does not exceed the allowable load, damage to the feed motor can be prevented in advance.

The present invention is proposed in view of the above situation, and one of its purposes is to provide a control device and a working machine having the same that can start turning processing when the eccentric body is in an arbitrary phase. Another purpose is to provide a control device and a working machine having the same that can process eccentric bodies of various shapes. Another purpose is to provide a control device and a working machine having the same that can ensure that the load acting on the feed motor does not exceed the allowable load when processing the eccentric body.

The present invention for solving the above-mentioned problems is a control device, which controls the operation of the spindle drive unit and the feed drive unit of a working machine having a spindle that holds a workpiece and rotates the workpiece, a tool holding unit that holds a tool, a spindle drive unit that rotates the spindle, and a feed drive unit that moves the tool holding unit and the spindle relative to each other along a Z-axis that is consistent with the axis of the spindle, an X-axis that is orthogonal to the Z-axis, and a Y-axis that is orthogonal to the X-axis and the Z-axis. The control device comprises: a control unit that controls the spindle drive unit and the feed drive unit; and an eccentric cutting control unit that controls the eccentric cutting of the workpiece held by the spindle and is set at a position away from the center of the spindle. The eccentric body is machined with its center at a position after radial displacement, and the eccentric cutting control unit is configured to rotate the spindle in cooperation with the control unit. After positioning the eccentric body so that its center is on the X-axis, the distance from the center of the spindle to the center of the eccentric body, i.e., the eccentricity, is set to R, and the rotation angle of the spindle axis around the X-axis with the center of the eccentric body as a reference is set to θ. In synchronization with the rotation of the spindle, the tool is relatively moved while being relatively moved in the Z-axis direction, so as to perform an arc motion that describes an arc trajectory in which the position X in the X-axis direction and the position Y in the Y-axis direction are the values of the following equations (1) and (2), respectively.

X＝Rcosθ· · · (1)

Y＝Rsinθ· · · (2)

According to the control device, the eccentric cutting control unit and the control unit cooperate to rotate the main shaft, position the eccentric body in a manner such that the center position is located on the X-axis, and move the tool to the turning start position in the three-dimensional space formed by the X-axis, the Y-axis, and the Z-axis. At this time, the tool tip is in a non-contact state with the workpiece, and is in a state where it can contact the outer peripheral surface of the eccentric body at a predetermined cutting depth through movement in the Z-axis direction described later.

Next, the eccentricity, that is, the distance from the center of the spindle to the center of the eccentric body, is set to R, and the rotation angle of the spindle axis around the X-axis with the center of the eccentric body as the reference is set to θ. In synchronization with the rotation of the spindle (phase θ), the tool is moved relatively while moving relatively in the Z-axis direction so that the position X in the X-axis direction and the position Y in the Y-axis direction describe an arc trajectory of a radius R.

The tool is relatively moved synchronously with the rotation of the spindle (phase θ) so that position X=Rcosθ and position Y=Rsinθ, thereby following the rotation of the eccentric body and making the tool contact the outer peripheral surface of the eccentric body rotating around the axis of the spindle. In addition, by moving the tool in the Z-axis direction in this state, the outer periphery of the eccentric body can be processed.

As described above, according to the control device involved in the present invention, even if the phase of the eccentric body when holding the workpiece on the spindle is different for each workpiece, after positioning in such a manner that the center position of the eccentric body is located on the X-axis, it is possible to start processing, so there is no need to hold the workpiece on the spindle in such a manner that the phase of its eccentric body becomes a predetermined reference phase as in the conventional processing method, and various workpieces can be processed without performing tedious adjustment work when the spindle holds the workpiece. In addition, by setting it in the above manner, the NC (Numerical Control) processing program used for the processing can be set as a processing program in which the reference position in the processing is set on the X-axis.

Furthermore, a general-purpose object can be applied to a holding device for holding a machine tool and a workpiece.

In addition, in the present invention, the control unit is configured to execute three control modes, namely, a speed control mode for rotating the spindle at a specified rotational speed, a position control mode for positioning the spindle at a specified rotational angle position around its axis, and a synchronous control mode for synchronizing the action of the spindle drive unit with the action of the feed drive unit, and the eccentric cutting control unit can be configured to synchronize the action of the spindle drive unit with the action of the feed drive unit by converting the control unit into the synchronous control mode.

In addition, in the present invention, the eccentric body is a lead along the Z-axis direction, and the eccentric cutting control unit can be configured to set the length of the eccentric body in the Z-axis direction to LengZ, set the phase increase or decrease value of the eccentricity in the Z-axis direction to Q, cooperate with the control unit, and synchronize with the feed amount ΔZ in the Z-axis direction per unit time, and set the phase change value Δφ per unit time to the following formula (3), so as to make the tool move relatively.

【Formula 1】

According to the control device of this aspect, when the longitudinal direction of the eccentric body is the Z-axis direction, the outer peripheral surface thereof can be processed. In addition, as the lead shaft, a screw or the like can be exemplified.

Alternatively, in the present invention, the eccentric body is a lead along the Z-axis direction, and the eccentric cutting control unit can be configured to set the length of the eccentric body in the Z-axis direction to LengZ, set the eccentricity increase or decrease value of the eccentricity in the Z-axis direction to K, cooperate with the control unit, and synchronize with the feed amount ΔZ in the Z-axis direction per unit time, and set the eccentricity R to the following formula (4), so as to make the tool move relatively.

[Formula 2]

With this type of control device, even when the longitudinal direction of the eccentric body is the Z-axis direction, the outer peripheral surface can be processed.

Furthermore, the control device in the present invention may be configured to perform turning processing without synchronizing the operation of the spindle drive unit and the operation of the feed drive unit at least via the control unit.

In addition, the eccentric cutting control unit in the present invention may be configured to perform feedforward control on the feed drive unit in cooperation with the control unit.

In addition, the eccentric cutting control unit in the present invention can be configured to cooperate with the control unit to control the composite speed of the feed speed of the feed drive unit and the angular velocity in the circular motion to be less than or equal to a predetermined limit speed, and the composite speed is set in a manner such that the load in the feed drive unit does not exceed the range of the allowable load.

According to the control device of this aspect, since control is performed so that the load on the feed drive unit does not exceed the allowable load, damage to the feed drive unit can be prevented in advance.

In addition, the eccentric cutting control unit in the present invention can be configured to cooperate with the control unit to control the acceleration of the uniform circular motion in the arc motion to be less than or equal to a predetermined limit acceleration, and the limit acceleration is set so that the load in the feed drive unit does not exceed the range of the allowable load.

According to the control device of this method, the feed drive unit is controlled so that the acting load does not exceed the range of the allowable load, and the acceleration of the uniform circular motion in the arc motion is less than or equal to the specified limit acceleration. Therefore, the feed drive unit can be operated in a stable state and damage to the feed drive unit can be prevented in advance.

In addition, the present invention is a working machine, which has a spindle for holding a workpiece and rotating the workpiece, a tool holding portion for holding a tool, a spindle driving portion for rotating the spindle, a feed driving portion for relatively moving the tool holding portion and the spindle along a Z-axis consistent with the axis of the spindle, an X-axis orthogonal to the Z-axis, and a Y-axis orthogonal to the X-axis and the Z-axis, and a control device for any of the above items.

Effects of the Invention

As described above, according to the control device involved in the present invention and the working machine having the same, even if the phase of the eccentric body when holding the workpiece on the main spindle is different for each workpiece, processing can be started after positioning the eccentric body in such a way that the center position is located on the X-axis. Therefore, there is no need to perform tedious adjustment operations when holding the workpiece on the main spindle as in the prior art, and various workpieces can be processed efficiently.

Furthermore, since a general-purpose device can be used for holding a machine tool and a workpiece, equipment cost can be reduced, and since dedicated production changeover adjustment (adjustment work) is not required, productivity can be improved.

In addition, it is possible to process eccentric bodies having various shapes and forms, such as lead shafts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram for explaining an example of a method for machining an eccentric body using a machine tool according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a schematic configuration of a machine tool according to the present embodiment.

FIG. 3 is an explanatory diagram showing an example of the outline of eccentric cutting according to the present embodiment.

FIG. 4 is an explanatory diagram showing an example of the NC program according to the present embodiment.

FIG. 5 is a flowchart showing an example of the eccentric cutting control unit and the processing in the control unit according to the present embodiment.

FIG. 6 is a perspective view showing another example of processing of a workpiece according to the present embodiment.

FIG. 7 is an explanatory diagram showing an example of an outline of eccentric cutting according to Modification 1 of the present embodiment.

FIG. 8 is an explanatory diagram showing an example of an NC program according to Modification 1. FIG.

FIG. 9 is a flowchart showing an example of the eccentric cutting control unit and the processing in the control unit according to the first modification.

FIG. 10 is an explanatory diagram showing an example of an outline of eccentric cutting according to Modification 2 of the present embodiment.

FIG. 11 is an explanatory diagram showing an example of an NC program according to Modification 2. FIG.

Detailed ways

Hereinafter, a specific embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an explanatory diagram for describing an example of a method for processing an eccentric body of a working machine according to an embodiment of the present invention. FIG. 2 is a block diagram showing an example of a schematic structure of a working machine according to the present embodiment. In addition, as shown in FIG. 1 , a workpiece W, which is a processing object in the present example, has a base Wa set in a cylindrical shape, and a cylindrical eccentric body Wb protruding forward from the front end surface of the base Wa and set at a position offset by a distance R in the radial direction from the axis of the base Wa and having a radius r.

As shown in Figures 1 and 2, the working machine 1 of this example has a spindle 2, a chuck 3 for gripping a base Wa of a workpiece W while being loaded on the spindle 2, a tool holder 4 for holding a tool T, a drive unit 10, a control device 20 for controlling the drive unit 10, and an input-output device 30.

In addition, the working machine 1 in this example is a general-purpose horizontal NC lathe, but the working machine that can be applied to the present invention is not limited to this. In addition to vertical NC lathes, various working machines such as a working machine configured as a composite processing type capable of turning and milling can also be applied.

The drive unit 10 includes: a spindle drive unit 15 that drives and controls the spindle motor that rotates the spindle 2; and a feed drive unit 11 that drives and controls the motor of the feed device that moves the tool holder 4. The feed drive unit 11 includes: an X-axis feed drive unit 12 that drives and controls the motor of the X-axis feed device that moves the tool holder 4 in the X-axis direction; a Y-axis feed drive unit 13 that drives and controls the motor of the Y-axis feed device that moves the tool holder 4 in the Y-axis direction; and a Z-axis feed drive unit 14 that drives and controls the motor of the Z-axis feed device that moves the tool holder 4 in the Z-axis direction. In addition, in this example, the Z-axis is set to the same axis as the axis of the spindle 2, the X-axis is horizontally orthogonal to the Z-axis, and the Y-axis is orthogonal to both the X-axis and the Z-axis.

Thus, the tool rest 4 moves in the X-axis, Y-axis and Z-axis directions by the actions of the X-axis feed device, the Y-axis feed device and the Z-axis feed device driven and controlled by the feed drive unit 11. Thus, the tool T moves in a three-dimensional space defined by the X-axis, the Y-axis and the Z-axis. In addition, the spindle 2 is driven by a spindle motor driven and controlled by the spindle drive unit 15, and rotates around its axis.

The input/output device 30 includes, for example, a display with an input function such as a touch panel, an input/output interface for inputting and outputting data, etc. Of course, images and text information can be displayed on the display with an input function, and input can be performed via the input function.

The control device 20 includes an NC program storage unit 21 , a program analysis unit 22 , a control unit 23 , a parameter storage unit 26 , and an eccentric cutting control unit 27 .

In addition, the control device 20 is a numerical control device, which is composed of a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc. The program analysis unit 22, the control unit 23 and the eccentric cutting control unit 27 realize their functions through computer programs and execute the processing described later. In addition, the NC program storage unit 21 and the parameter storage unit 26 are appropriately composed of storage media such as RAM.

The NC program storage unit 21 is a functional unit for storing NC programs (machining programs) for NC control, for example, NC programs input from the input/output device 30. In addition, the parameter storage unit 26 is a functional unit for storing setting values of parameters in eccentric cutting, i.e., eccentric clamping speed, eccentric clamping acceleration, and eccentric feedforward gain, for example, parameters input from the input/output device 30.

The program analysis unit 22 sequentially reads out each program block constituting the NC program to be executed from the NC program stored in the NC program storage unit 21, and processes the NC code contained in the program block. When processing the NC code related to feed control, the program analysis unit 22 sends the instructions related to the NC code to the control unit 23. When processing the NC code related to rotation control, the program analysis unit 22 sends the instructions related to the NC code to the control unit 23.

In addition, the program analysis unit 22 distinguishes between the eccentric cutting instruction and other instructions. In the case of the eccentric cutting instruction, the program analysis unit 22 sends the instruction required for the eccentric cutting to the eccentric cutting control unit 27 and the control unit 23. In the case of other than the eccentric cutting instruction, the program analysis unit 22 sends the corresponding instruction to the control unit 23.

The control unit 23 includes a feed control unit 24 and a spindle control unit 25. The feed control unit 24 is a functional unit that controls the operation of the X-axis feed device, the Y-axis feed device, and the Z-axis feed device via the X-axis feed drive unit 12, the Y-axis feed drive unit 13, and the Z-axis feed drive unit 14. The feed control unit 24 receives instructions related to feed control from the program analysis unit 22, and controls the X-axis feed drive unit 12, the Y-axis feed drive unit 13, and the Z-axis feed drive unit 14 so that the X-axis feed device, the Y-axis feed device, and the Z-axis feed device are operated at a speed corresponding to the received instructions.

The spindle control unit 25 is a functional unit that controls the rotation of the spindle motor via the spindle drive unit 15. The spindle control unit 25 receives a command related to the rotation control from the program analysis unit 22, and controls the spindle drive unit 15 so that the spindle motor rotates in the rotation direction and at the rotation speed corresponding to the received command.

The control unit 23 can operate in two processing modes, namely, a speed control mode and a position control mode, with respect to the spindle control unit 25 in accordance with the instruction from the program analysis unit 22, and can operate in a synchronous control mode with respect to the spindle control unit 25 and the feed control unit 24. The speed control mode is a mode in which the spindle motor is rotated at a predetermined rotation speed. The position control mode is a mode in which the spindle motor is positioned at a predetermined rotation angle position around its axis. The synchronous control mode is a mode in which the operation of the spindle motor is synchronized with the operation of the X-axis feed device, the Y-axis feed device, and the Z-axis feed device.

Furthermore, in the speed control mode, the spindle control unit 25 outputs the angular position data for rotating the spindle motor at the rotation speed to the spindle drive unit 15 in accordance with the spindle rotation speed command sent from the program analysis unit 22. In the position control mode, the spindle control unit 25 outputs the angular position data for positioning the spindle motor at a designated angular position around its axis to the spindle drive unit 15 in accordance with the angular position command sent from the program analysis unit 22. In addition, in the synchronization control mode, the spindle control unit 25 synchronizes the operation of the spindle motor with the operation of the X-axis feed device, the Y-axis feed device, and the Z-axis feed device in accordance with the synchronization command sent from the program analysis unit 22 or the eccentric cutting control unit 27.

The eccentric cutting control unit 27 receives the eccentric cutting command from the program analysis unit 22 , sends a command related to the eccentric cutting to the control unit 23 , and cooperates with the control unit 23 to cause the drive unit 10 to perform the eccentric cutting.

FIG. 3 is an explanatory diagram showing an example of the outline of the eccentric cutting involved in the present embodiment. FIG. 4 is an explanatory diagram showing an example of the NC program involved in the present embodiment. As shown in FIG. 3 (also refer to FIG. 1 ), regarding the eccentric body Wb, its axis is eccentric from the axis of the workpiece W (i.e., the axis of the spindle 2) in the X-axis direction by a distance R (hereinafter referred to as the eccentricity R). In addition, the axis on the positive side of the X-axis of the eccentric body Wb is set as the reference axis, and the angular position (phase) in the clockwise direction with the spindle axis as the center is set as C. The angular position C represents the angular position of the eccentric body Wb when the workpiece W is mounted on the spindle 2, that is, the indexing position of the spindle 2 for determining the forming position of the eccentric body Wb. In addition, the spindle 2 rotates during processing, and thereby the position of the eccentric body Wb also rotates with the spindle axis as the center. The rotation angle of the spindle axis around the axis on the positive side of the X-axis as the reference axis at any time of the spindle rotation command for the eccentric body Wb is set as θ. In addition, the following mainly describes the NC codes unique to eccentric cutting.

In FIG. 4 , code “M45” is a command for switching to the position control mode. The command M45 is sent from the program analysis unit 22 to the control unit 23 , and upon receiving the command, the spindle control unit 25 switches to the position control mode.

The code "G128" is a code related to the eccentric cutting control, "P" defines whether it is valid or invalid, "P1" means that the eccentric cutting control is valid, and "P0" means that the eccentric cutting control is invalid. In addition, "R" is the eccentricity, and "C" is the phase (eccentric phase) of the eccentric body Wb. Moreover, if these codes are recognized by the program analysis unit 22, the instructions related to the start of eccentric cutting and the information related to eccentric cutting are sent to the eccentric cutting control unit 27, and in cooperation with the control unit 23, the processing shown in Figure 5 described later is performed.

In addition, the code "G50" is a command to limit (ie, clamp) the maximum rotation speed of the spindle motor, and the code "G96" is a command to control the peripheral speed to be constant. In addition, "S" is a speed command.

Next, the eccentric cutting control executed in cooperation between the eccentric cutting control unit 27 and the control unit 23 will be described in detail based on Fig. 5. Fig. 5 is a flowchart showing an example of the processing in the eccentric cutting control unit and the control unit according to the present embodiment.

The control unit 23 first calculates the eccentricity deviation amount obtained by adding the eccentricity R (=10 mm) to the offset amount of the X axis based on the eccentricity R received from the program analysis unit 22, and controls the subsequent machine coordinates based on the eccentricity deviation amount (step S1).

Next, the eccentric cutting control unit 27 sends the instruction related to the eccentric phase C (=90°) received from the program analysis unit 22 to the control unit 23, and under the control of the spindle control unit 25 and the spindle drive unit 15, the spindle motor is rotated in the opposite direction at the angle of the eccentric phase C (90°), and the center position of the eccentric body Wb is positioned on the X-axis (step S2). That is, in this case, the C-axis positions the position of the spindle 2 around the axis at the position of the eccentric phase C. Thus, the forming position of the eccentric body Wb is determined. In addition, at this time, the control unit 23 receives the instruction of the position control mode related to the code "M45" from the program analysis unit 22, and switches the processing mode of the spindle control unit 25 to the position control mode. In addition, in the above example, the spindle motor is rotated in the opposite direction at the angle of the eccentric phase C (90°), but it can also be rotated at the angle of the eccentric phase C (90°) ± 360° × n (where n is 0 or a natural number). In short, the eccentric body Wb may be rotated so that the center thereof is located on the X-axis. However, the smaller the value of n is, the better it is, and the processing time can be shortened.

Next, the eccentric cutting control unit 27 sends a command related to the synchronous control mode to the control unit 23, and switches the spindle control unit 25 and the feed control unit 24 to the synchronous control mode (step S3). Thus, by executing the above sequence, the eccentric cutting control state is achieved.

Next, the eccentric cutting control unit 27 calculates the spindle rotation speed based on the speed instruction S and the spindle ratio sent from the program analysis unit 22, and clamps (limits) the spindle rotation speed with reference to the parameter storage unit 26 so that it does not exceed the rotation speed calculated based on the eccentric clamping acceleration or the rotation speed of the G50 instruction (step S4).

In the eccentric cutting control, the tool T is synchronized with the spindle rotation speed S in the X-axis-Y-axis plane to perform an eccentric circular motion with an eccentric amount R. If the angular velocity of the spindle 2 is ω and the time is t, the command positions X and Y of the X-axis and Y-axis in the eccentric circular motion are respectively expressed by the following equations (5) and (6). In addition, ωt corresponds to the rotation angle θ of the spindle 2.

X＝Rcos(ωt) ··· (5)

Y＝Rsin(ωt) ··· (6)

Furthermore, in equations (5) and (6), if the maximum acceleration of the constant circular motion is set to A, the maximum acceleration A is expressed by the following equation (7).

A＝Rω ² ＝R(2πS) ² ··· (7)

Therefore, by setting the maximum acceleration A as the eccentric clamp acceleration, the clamp spindle rotation speed S _clamp can be set by the following equation (8).

S _clamp ≤(1/(2π))×(A/R) ^1/2 ··· (8)

Next, the eccentric cutting control unit 27 calculates the eccentric circular arc movement amount in the X-axis-Y-axis plane based on the spindle rotation speed after being limited by the clamped spindle rotation speed S _clamp set in step S4 (step S5). If the spindle rotation angle per control unit time T is set to Δθ, the eccentric circular arc movement amounts ΔX and ΔY of the X-axis and Y-axis are calculated by the following equations (9) and (10). In addition, the eccentric clamping acceleration is preferably set within the range where the load in the X-axis feed device and the Y-axis feed device does not exceed the allowable load. As described above, damage to the X-axis feed device and the Y-axis feed device can be prevented in advance.

ΔX＝Rcos(Δθ) ··· (9)

ΔY＝Rsin(Δθ) ··· (10)

Then, the eccentric cutting control unit 27 calculates the eccentric arc movement amounts ΔX and ΔY at the control unit time T as described above, and sequentially sends the calculated eccentric arc movement amounts ΔX and ΔY to the control unit 23 .

Then, in the control unit 23, the feed control unit 24 and the spindle control unit 25 cooperate to rotate the spindle motor at a speed less than or equal to the clamp spindle rotation speed S _clamp , and in synchronization with the rotation angle position, the X-axis feed device and the Y-axis feed device are driven via the X-axis feed drive unit 12 and the Y-axis feed drive unit 13 so that the tool T is moved according to the eccentric circular arc movement amounts ΔX and ΔY sent from the eccentric cutting control unit 27. In addition, the feed control unit 24 adds these eccentric circular arc movement amounts ΔX and ΔY to the movement amounts in the X-axis and Y-axis directions sent from the program analysis unit 22, thereby correcting the movement amounts.

In addition, when the circular motion using the X-axis feed device and the Y-axis feed device is controlled, the response delay caused by the position loop gain causes an inward rotation, and the actual processing position becomes smaller than the specified eccentricity R. Therefore, the eccentric cutting control unit 27 applies the eccentricity feedforward gain stored in the parameter storage unit 26 to the eccentric circular arc movement amounts ΔX and ΔY to suppress the inward rotation. That is, the eccentric cutting control unit 27 performs feedforward control on the feed drive unit 11 in cooperation with the control unit 23.

The control unit 23 determines whether a normal turning instruction is received from the program analysis unit 22 (step S6). When the control unit 23 receives a normal turning instruction from the program analysis unit 22 (step S6 indicates yes), the control unit 23 calculates the movement amount of each feed device based on the instruction (step S7). The turning instruction includes not only an early feed instruction or a cutting instruction, but also a turning instruction such as thread cutting.

Here, the control unit 23 clamps so that the movement amount of the normal turning instruction does not exceed the eccentric clamping speed stored in the parameter storage unit 26. The reason is that the eccentric arc movement amounts ΔX and ΔY are always corrected independently of the command value of the NC program, so the composite speed with the normal turning instruction will exceed the clamping speed of the early feed or cutting feed. Therefore, clamping is performed with the movement amount calculated according to the speed obtained by subtracting the eccentric clamping speed from the clamping speed of the early feed or cutting feed (step S8). That is, the eccentric cutting control unit 27 is configured to cooperate with the control unit 23 to control the composite speed of the feed speed of the feed drive unit 11 and the angular velocity in the arc motion to be less than or equal to a predetermined limit speed. In addition, the composite speed is preferably set within the range where the load in the feed drive unit 11 does not exceed the allowable load.

Next, the control unit 23 adds the normal command movement amount and eccentric arc movement amounts ΔX and ΔY calculated by considering the eccentricity R and the eccentric clamping speed relative to the program command position, and outputs them to the drive unit 10 as position commands, thereby realizing the processing of the eccentric body Wb (step S9).

That is, as shown in FIG. 3 , it is assumed that the workpiece W rotates clockwise at a rotation speed S, and the tool T performs eccentric circular motion clockwise in synchronization with the rotation, thereby achieving a state in which the tool T contacts the outer peripheral surface of the eccentric body Wb.

Thus, after the tool T is positioned at a position where the tip of its blade is separated from the end face of the eccentric body Wb in the positive direction of the Z axis by a specified distance, and is in a state of cutting in the X axis direction at a specified cutting depth relative to the outer periphery of the eccentric body Wb, the tool T is synchronized with the rotation of the workpiece W, moving in the Z axis direction while performing an arc motion with a radius R, thereby the outer peripheral surface of the eccentric body Wb is turned by the tool T.

The control unit 23 performs acceleration and deceleration processing only for the movement amount normally commanded. This is because the eccentric arc movement amounts ΔX and ΔY are synchronized with the acceleration and deceleration of the spindle rotation speed, and acceleration and deceleration processing is unnecessary from the viewpoint of suppressing inward rotation.

Next, the eccentric cutting control unit 27 and the control unit 23 determine whether an instruction related to the end of eccentric cutting is received from the program analysis unit 22 (step S10). If the eccentric cutting control unit 27 and the control unit 23 receive an instruction related to the end of eccentric cutting from the program analysis unit 22 (if step S10 is yes), the eccentric cutting control unit 27 stops the calculation of the eccentric arc movement amounts ΔX and ΔY (step S11), and the control unit 23 terminates the processing after releasing the synchronous control mode (step S12). If the synchronous control mode is released in step S12, the control device 20 performs the synchronous turning processing without the operation of the spindle drive unit 15 and the operation of the feed drive unit 11 via at least the control unit 23.

On the other hand, in step S10, when the eccentric cutting control unit 27 and the control unit 23 do not receive instructions related to the end of eccentric cutting from the program analysis unit 22 (when step S10 is no), the eccentric cutting control unit 27 and the control unit 23 repeat the processing from steps S4 to S9.

In addition, when it is identified in step S6 that the normal turning instruction is not received (when step S6 is "no"), the eccentric cutting control unit 27 and the control unit 23 determine whether the instruction related to the eccentric cutting control is received from the program analysis unit 22 (step S13). When the instruction related to the eccentric cutting control is received again (when step S13 is "yes"), the control unit 23 first changes the eccentric deviation amount based on the eccentricity R newly received from the program analysis unit 22 (step S14), and after calculating the phase difference between the previous eccentric phase and the current eccentric phase (step S15), executes step S4 and subsequent processing. Moreover, in step S4, the spindle motor is accelerated and decelerated in such a way that the phase difference is set to 0, thereby enabling a plurality of eccentric bodies Wb to be formed at any position through a single eccentric cutting control, and enabling more efficient processing of the crank pin, etc. In addition, when it is recognized in step S13 that the command related to the eccentric cutting control has not been received (in the case of no in step S13), the processing of step S4 and thereafter is also executed.

According to the working machine 1 of this example constructed as described above, even if the eccentric phase C of the eccentric body Wb when the workpiece W is held on the chuck 3 (spindle 2) is different for each workpiece W, it is possible to start processing after positioning so that the center position of the eccentric body Wb is located on the X-axis. Therefore, there is no need to hold the workpiece W on the chuck 3 (spindle 2) in such a way that the eccentric phase C of its eccentric body Wb becomes a prescribed reference phase as in the existing processing method. Therefore, when the chuck 3 (spindle 2) holds the workpiece W, various workpieces W can be processed without performing tedious adjustment operations.

In addition, the drive unit 10 and the chuck 3 of the machine tool 1 can conventionally adopt general-purpose structures.

In addition, in this embodiment, the workpiece _W1 shown in FIG. 6 can be processed. FIG. 6 is an oblique view showing an example of processing of another workpiece involved in this embodiment. The workpiece _W1 is an eccentric body _Wb1 protruding in the Z-axis direction from the base _Wa1 , and the eccentricity R in the Z-axis direction is constant, but the radius r changes in the protruding direction. In the method shown in FIG. 6, the radius r increases in the protruding direction. The radius r is the distance of the X-axis coordinate instruction specified by the program from the center position of the eccentric body _Wb1 . Therefore, by specifying the positions of the X-axis and the Z-axis through the usual turning instructions, it is possible to form any shape in which the radius r changes in the protruding direction based on the eccentricity R.

Modification 1

Next, a modification example 1 of the above-mentioned embodiment will be described. FIG7 is an explanatory diagram showing an example of an outline of eccentric cutting involved in the modification example 1 of the present embodiment. In the modification example 1, the workpiece _W2 shown in FIG7 is processed. The workpiece _W2 has a base _Wa2 set in a cylindrical shape and an eccentric body Wb2 protruding from its front end surface in the Z-axis direction and formed at a position offset from the axis of the base _Wa2 in the radial direction by an eccentricity amount R, and _the eccentric body _Wb2 has a shape in which its axis is inclined (offset) toward the axis side of the base _Wa2 .

FIG8 is an explanatory diagram showing an example of an NC program involved in variant example 1. FIG8 shows an example of an NC program for processing an eccentric body _Wb2 of a workpiece _W2 . As shown in FIG8, in this example, compared with the NC program shown in FIG4, the difference is that the instruction in sequence N08 becomes "G128 P2 Z-30.K10.F2.". The code "G128P2" is an eccentric cutting control phase shift instruction, which defines that "Z" is the movement amount of the lead shaft (30 mm in the Z-axis direction in this example), "K" is the change in the eccentricity in the radial direction (10 mm in this example), and "F" is the synchronous feed speed (2 mm/per rotation in this example). In addition, the change in the eccentricity in the radial direction, that is, the eccentricity change "K" is the eccentricity increase or decrease value of the eccentricity.

In this NC program, the processing shown in FIG. 9 is performed in cooperation with the eccentric cutting control unit 27 and the control unit 23. FIG. 9 is a flowchart showing an example of the processing in the eccentric cutting control unit and the control unit of Modification 1. In addition, the processing shown in FIG. 9 performs the processing of steps S16 and S17 after step S13 of the processing shown in FIG. 5, so the other processing is the same as the processing shown in FIG. 5. Therefore, only the processing of steps S16 and S17 will be described below, and the description of other processing will be omitted.

When it is recognized in step S13 that no command related to eccentric cutting control is received (if step S13 is No), the control unit 23 determines whether an eccentric cutting control phase shift command and information related thereto are received from the program analysis unit 22 (step S16). When it is recognized that no eccentric cutting control phase shift command and information related thereto are received from the program analysis unit 22 (if step S16 is No), the processing of step S4 and thereafter is performed.

In addition, if it is recognized that the eccentric cutting control phase shift instruction and the information related thereto are received from the program analysis unit 22 (if the step S16 is yes), the eccentric cutting control unit 27 calculates the eccentric arc movement amount under the shift control and sends it to the control unit 23 (step S17). Specifically, the eccentric cutting control unit 27 calculates the eccentric arc action increase/decrease value, and calculates the final eccentric arc movement amount obtained by adding the eccentric arc action increase/decrease value to the eccentric arc movement amount calculated in step S5, and sends it to the control unit 23.

The eccentric arc movement amounts ΔX and ΔY are calculated as follows based on the movement amount Z of the lead shaft, the eccentricity change amount K, and the synchronous feed speed F.

First, the change amount ΔR of the eccentricity R per unit time is expressed by the following equation (11): wherein ΔZ is the movement amount of the lead shaft per control unit time T, and is calculated based on the synchronous feed speed F.

[Formula 3]

Therefore, the eccentricity R used in equations (9) and (10) is as shown in equation (12) below, which is the eccentricity R in consideration of the eccentricity change amount K in the Z-axis direction.

[Formula 4]

Therefore, the eccentric arc movement amounts ΔX and ΔY can be calculated not by equations (9) and (10) but by the following equations (13) and (14).

ΔX＝(R+ΔR)cos(Δθ) · · · (13)

ΔY＝(R+ΔR)sin(Δθ) · · · (14)

The eccentric cutting control unit 27 cooperates with the control unit 23 to relatively move the tool T using the eccentricity R shown in equation (12). Thus, according to this modification 1, the eccentric body _Wb2 of the workpiece _W2 shown in FIG.

Modification 2

Next, modification example 2 is described. In this modification example 2, the workpiece _W3 shown in Figure 10 is processed. Figure 10 is an explanatory diagram showing an example of the outline of the eccentric cutting involved in modification example 2 of the present embodiment. The workpiece _W3 has a base _Wa3 set in a cylindrical shape and an eccentric body Wb3 protruding from its front end surface in the Z-axis direction and formed at a position offset by an eccentricity R in the radial direction from the axis of the base _Wa3 . _The eccentric body _Wb3 has a shape in which its axis is twisted in a spiral shape along the Z-axis direction, that is, a shape in which the eccentric phase increases or decreases in the Z-axis direction. The workpiece _W3 is a component used in a rotary positive displacement uniaxial eccentric screw pump.

FIG11 is an explanatory diagram showing an example of an NC program involved in variant example 2. FIG11 shows an example of an NC program for processing the eccentric body Wb ₃ of the workpiece W ₃ of FIG10 . As shown in FIG11 , in this example, compared with the NC program shown in FIG4 , the difference is that the instruction in sequence N08 becomes "G128 P2 Z-90.Q1080.F2.". The code "G128P2" is an eccentric cutting control phase shift instruction, which is defined as "Z" is the movement amount of the lead axis (90 mm in the Z-axis direction in this example), "Q" is the change in the eccentric phase (1080° (3 pitches) in this example), and "F" is the synchronous feed speed (2 mm/per rotation in this example). In addition, the change in the eccentric phase "Q" is the eccentric phase increase or decrease value.

In this NC program, in cooperation with the eccentric cutting control unit 27 and the control unit 23 , in the process of step S17 shown in FIG. 9 , the eccentric cutting control unit 27 calculates the eccentric arc movement amount under the offset control and sends it to the control unit 23 .

That is, the eccentric arc movement amounts ΔX and ΔY are calculated based on the movement amount LengZ of the lead axis, the eccentric phase change amount Q, and the synchronous feed speed F as follows.

First, the phase change value Δφ per control unit time T is expressed by the following equation (15). ΔZ is the movement amount of the lead axis per control unit time T, and is calculated based on the synchronous feed speed F.

[Formula 5]

Moreover, the phase of the eccentric body Wb ₃ in equations (9) and (10) is as shown in equation (16), which is the sum of the main shaft rotation angle Δθ per control unit time T and the phase change value Δφ per unit time. Therefore, the eccentric arc movement amounts ΔX and ΔY are calculated by equations (16) and (17) and sent to the control unit 23.

ΔX＝Rcos(Δθ+Δφ) · · · (16)

ΔY＝Rsin(Δθ+Δφ) · · · (17)

In addition, the angle from the X-axis at any time relative to the spindle rotation speed command S is θ, and the spindle rotation angle per control unit time T relative to the spindle rotation speed command S is Δθ. The XY movement amount per control unit time T is expressed by equations (9) and (10). The phase change value Δφ per unit time is expressed by equation (15), and the movement amount obtained by adding the phase change value Δφ per unit time is expressed by equations (16) and (17). As mentioned above, the command positions X and Y of the X-axis and Y-axis in the eccentric circular arc motion expressed by equations (1) and (2) are expressed by the following equations (18) and (19).

[Formula 6]

[Formula 7]

Therefore, according to this modification 2, the eccentric body _Wb3 of the workpiece _W3 shown in FIG. 10 can be processed.

As described above, not only the eccentricity condition determined when the eccentric cutting control is commanded, but also the eccentricity condition is changed synchronously with the movement in the Z-axis direction, thereby making it easy to process the workpieces _W1 , _W2 , and _W3 as shown in Figures 6, 7, and 10. The change of the eccentricity condition as described above can be achieved by specifying the eccentric cutting control offset command based on the eccentric cutting control command.

As mentioned above, although the specific embodiment of this invention was described, the form which this invention can adopt is not limited to the arbitrary example mentioned above.

In the above example, part of the information related to eccentric cutting is set as NC code, but the present invention is not limited to this, and the information may be set as a parameter and stored in the parameter storage unit 26 .

In the above example, the mode is switched to the position control mode by the code “M45” specified in the NC program. However, the control unit 23 may autonomously switch to the position control mode to perform positioning.

Although repeated, the description of the above-mentioned embodiments is illustrative in all aspects, and the present invention is not limited thereto. It can be deformed and changed by those skilled in the art. In one example, it can also be combined with other known technologies, and a part of the structure can also be omitted or changed without departing from the scope of the main purpose. The scope of the present invention is not represented by the above-mentioned embodiments, but by the claims. In addition, the scope of the present invention includes changes relative to the embodiments within the scope equivalent to the claims.

Description of the label

1 working machine, 2 spindle, 3 chuck, 4 tool rest, 10 driving unit, 11 feed driving unit, 12 X-axis feed driving unit, 13 Y-axis feed driving unit, 14 Z-axis feed driving unit, 15 spindle driving unit, 20 control device, 21 NC program storage unit, 22 program analysis unit, 23 control unit, 24 feed control unit, 25 spindle control unit, 26 parameter storage unit, 27 eccentric cutting control unit, 30 input and output device.

Claims (9)

1. A control device controls the operation of a main shaft driving part and a feed driving part of a working machine, the working machine comprises: a spindle for holding a workpiece and rotating the workpiece; a tool holding unit for holding a tool; a spindle driving unit configured to rotate the spindle; and a feed drive unit that relatively moves the tool holder and the spindle along a Z axis aligned with an axis of the spindle, an X axis orthogonal to the Z axis, and a Y axis orthogonal to the X axis and the Z axis,

The control device is characterized by comprising:

a control unit that controls the spindle drive unit and the feed drive unit; and

An eccentric cutting control unit that processes an eccentric body of the workpiece held by the spindle, the eccentric body being provided at a position displaced in a radial direction from a center of the spindle,

The eccentric cutting control unit is configured to rotate the spindle in cooperation with the control unit, and then, after positioning the center position of the eccentric body on the X-axis, to make the distance from the center of the spindle to the center of the eccentric body, that is, the eccentric amount, R, and the rotation angle around the spindle axis with respect to the X-axis of the center of the eccentric body, θ, and to move the tool relatively in the Z-axis direction in synchronization with the rotation of the spindle, so that the position X in the X-axis direction and the position Y in the Y-axis direction are circular arc movements of circular arc trajectories of values of the following formulas (1) and (2), respectively,

X＝Rcosθ· · · (1)

Y＝Rsinθ· · · (2)。

2. The control device according to claim 1, wherein,

The control unit is configured to execute 3 control modes, namely a speed control mode for rotating the main shaft at a predetermined rotational speed, a position control mode for positioning the main shaft at a predetermined rotational angle position around the axis thereof, and a synchronous control mode for synchronizing the operation of the main shaft driving unit and the operation of the feed driving unit,

The eccentric cutting control unit is configured to synchronize the operation of the spindle drive unit with the operation of the feed drive unit by switching the control unit to the synchronization control mode.

3. Control device according to claim 1 or 2, characterized in that,

The eccentric body is a lead wire along the Z-axis direction,

The eccentric cutting control unit is configured to move the tool relative to each other by setting a length of the eccentric body in the Z-axis direction to LengZ, setting a phase increase and decrease value of the eccentric body in the Z-axis direction to Q, synchronizing with a feed amount DeltaZ in the Z-axis direction per unit time in cooperation with the control unit, setting a phase change value Deltaphi per unit time to the following formula (3),

[ 1]

4. Control device according to claim 1 or 2, characterized in that,

The eccentric body is a lead wire along the Z-axis direction,

The eccentric cutting control unit is configured to relatively move the tool by setting the length of the eccentric body in the Z-axis direction to LengZ, setting the eccentric amount increase/decrease value of the eccentric in the Z-axis direction to K, cooperating with the control unit, and synchronizing with the feed amount DeltaZ in the Z-axis direction per unit time, setting the eccentric amount R to the following formula (4),

[ 2]

5. The control device according to any one of claims 1 to 4, wherein,

The control device is configured to perform turning processing at least via the control unit without synchronization of the operation of the spindle drive unit and the operation of the feed drive unit.

6. The control device according to any one of claims 1 to 5, wherein,

The eccentric cutting control unit is configured to perform feedforward control on the feed drive unit in cooperation with the control unit.

7. The control device according to any one of claims 1 to 6, wherein,

The eccentric cutting control part is configured to control the combined speed of the feed driving part and the angular speed in the circular arc motion to be less than or equal to a predetermined limit speed in cooperation with the control part,

The combination speed is set in a range in which the load of the feed drive section does not exceed an allowable load.

8. The control device according to any one of claims 1 to 6, wherein,

The eccentric cutting control section is configured to control acceleration of the constant velocity circular motion in the circular arc motion to be less than or equal to a predetermined limit acceleration in cooperation with the control section,

The limit acceleration is set in a range in which the load of the feed drive section does not exceed an allowable load.

9. A machine tool, comprising:

A spindle for holding a workpiece and rotating the workpiece; a tool holding unit for holding a tool; a spindle drive unit for rotating the spindle; a feed drive unit that relatively moves the tool holding unit and the spindle along a Z axis aligned with an axis of the spindle, an X axis orthogonal to the Z axis, and a Y axis orthogonal to the X axis and the Z axis; and a control device according to any one of claims 1 to 8.