CN1995775A - Method for actively inhibiting pulsation of machine tool main shaft and device therefor - Google Patents

Abstract

The invention relates to a method and device for actively suppressing the runout of a machine tool spindle, belonging to the field of mechanical engineering. This method mainly uses the technology of electromagnetic force automatic suppression, applies the change of electromagnetic torque caused by the change of the gap of the magnetic coil produced by the radial runout, and uses the axial magnetic coil and the radial magnetic coil to respectively suppress the deflection and deflection caused by the radial runout of the main shaft. Radial displacement, thereby suppressing the radial runout of the spindle. The device is composed of a voltage power supply, an axial magnetic force coil group and a radial magnetic force coil group. The method and device of the invention can significantly improve the precision of the spindle.

Description

Active suppression method and device for machine tool spindle runout

technical field

The invention relates to a method and device for actively suppressing the runout of a machine tool spindle, belonging to the field of mechanical engineering.

Background technique

The machine tool spindle, especially the machine tool electric spindle of the machining center, is usually a cantilever beam structure with the motor as the fixed end. It is characterized in that the spindle motor drives the spindle rotor to rotate, and the rotor protrudes along one end of the motor to clamp the tool or workpiece. Due to the structure of the rotor itself or the inability to meet the dynamic balance after clamping the tool workpiece, the protruding end of the rotor will produce radial runout due to the action of external force, which will affect the machining accuracy and tool life.

Aiming at the position deviation of the main shaft, a system for measuring the position of the main shaft of the machine tool and using the error signal to control the main shaft position has been developed. For related technologies of this system, see US Patent No.: US3596153, title: POSITIONAL CONTROL SYSTEM FOR A MACHINETOOL. The main feature of the system is to measure the position of the main shaft of the machine tool and send the error signal to the vector control system to control the position of the main shaft of the machine tool. This patent can improve the positional accuracy of the spindle to improve the machining accuracy. However, controlling the position of the spindle relative to the workpiece does not change the internal structure of the spindle, and the factors leading to radial runout still exist.

Henan Xinji Co., Ltd. proposes a spindle structure to ensure the stability of the spindle, see Chinese application (patent) number: 200520030563.1, name: spindle structure of vertical steel ball grinding machine. The main feature of this mechanism is that there is a double-row cylindrical roller bearing with a taper in the hole radial direction between the main shaft and the support platform in the housing, and at the same time, the contact between the main shaft and the bearing is processed into a corresponding tapered mounting surface. This structure improves the stability of the main shaft by increasing the contact area between the main shaft and the bearing, and correspondingly reduces the radial runout of the main shaft, but the main shaft needs to be adjusted and maintained after wear and tear.

At the same time, China's application (patent) number: 01134647.7, title: internal active compensation method and device for tool axial deflection of rotating spindle, its main feature is to add an electromagnetic control module at the end of the spindle inside the spindle, and use non-contact The magnetic force is used to fine-tune the axial position of the mandrel. However, this patent needs to install a sensor outside the spindle to directly measure the axial deflection of the tool and use the measured data as a feedback signal, so the control system is relatively complicated, and the electromagnetic module added at the end of the spindle can only control The axial runout of the main shaft has no effect on controlling the radial runout.

In addition, US patent US6062778, title: Precision positioner fora cutting tool insert, relates to a radial positioning method and device for boring tools. It relates to a precise positioning device of a cutting tool, and the cutting tool is installed on a flexible component at the end of a boring bar. The flexible part is parallel to a radial axis perpendicular to the advancing direction of the tool; it is fixed along the feeding axis relative to the feeding direction of the tool; it is fixed along the cutting axis relative to the rotating direction of the tool. Displacement of the flexible member and cutting tool due to contact with the workpiece or chatter of the boring bar is detected by a laser detector. The detection signal will be input into the computer, which rotates with the boring bar and provides a feedback signal to the actuator connected to the flexible part, and the actuator drives the flexible part to correct the position of the tool. The disadvantage is that it needs to use a laser displacement sensor to detect the position of the tool and flexible parts, and use a microcomputer to process the detection model. The system control method is complicated and the cost is high. At the same time, the method of using the actuator to adjust the position of the flexible component and the tool will cause a new dynamic balance problem. When the spindle speed is further increased, such as a high-speed machining machine with a speed of up to 50,000 rpm, high machining accuracy is required, and the problem of radial runout will also increase. show up. First of all, as the spindle speed increases, the requirements for the dynamic balance of the spindle increase accordingly. Even if the above-mentioned patent is used for balancing, the radial runout of the spindle cannot be effectively controlled. This is because the main adjustment components of this patent are all mechanical structures, which also have certain dynamic balance problems, which will be exposed under high-speed rotation. Secondly, even a small spindle runout in high-precision machining will cause the loss of machining accuracy and result in unqualified products. Therefore, it is necessary to further control the radial runout of the spindle to meet the needs of high-precision production.

Contents of the invention

Aiming at the disadvantages of high cost of mechanical control, complicated structure, and limited performance, the present invention proposes a method and device for actively suppressing the runout of the main shaft of a machine tool that reduces the radial runout of the main shaft and is suitable for assembly of high-speed and high-precision machine tools.

A method for actively suppressing the runout of a machine tool spindle, characterized in that electromagnetic force coils are respectively installed on the spindle rotor and the spindle mounting frame, and a certain gap is reserved to form a radial magnetic force coil group and an axial magnetic force coil group respectively, wherein:

(a), make the minimum value of the radial magnetic coil group gap greater than the maximum radial amplitude generated by the radial runout of the main shaft at the installation place of this group of coils, and the maximum value satisfies the force between the group of magnetic coils not less than The gap is 50% of the force at zero time; when the spindle runs out radially, the gap between the radial magnetic coil groups changes, producing an electromagnetic resultant force in the positive direction and the amplitude of the radial runout of the main shaft. On the contrary, it is applied to the extended end of the spindle rotor so that the spindle beating is suppressed;

(b), at the same time, make the minimum value of the gap between the axial magnetic coil groups greater than the maximum axial amplitude generated by the radial runout of the main shaft at the installation place of this group of coils, and the maximum value satisfies the force between the group of coils. It is less than 50% of the force when the gap is zero; when the spindle has a radial runout that causes the spindle to swing, the gap of the axial magnetic coil group changes, and an electromagnetic torque that is positive to the amplitude of the radial runout of the spindle is generated. The direction is opposite to the swing direction, which is applied to the extended end of the spindle rotor so that the spindle runout is suppressed.

An active suppressing device for spindle runout of a machine tool, characterized in that the device is composed of two sets of magnetic coils and a voltage power supply, wherein:

(a), the first group of magnetic coil groups is a radial magnetic coil group, which is composed of a magnetic coil I installed on the extreme end of the rotor and a magnetic coil II opposite to it and installed on the mounting frame. The magnetic coil I and There is a radial gap in the radial direction of the magnetic coil II; and the minimum value of the radial gap between the magnetic coil I and the magnetic coil II is greater than the maximum radial amplitude generated by the radial runout of the main shaft at the installation of these two coils, and the maximum value satisfies Make the force between the magnetic coil I and the magnetic coil II not less than 50% of the force when the gap is zero;

(b), the second set of magnetic coils is an axial magnetic coil set, which is located between the first set of magnetic coils and the bearing at the extension end of the rotor. It consists of magnetic coils III, magnetic coils IV, and magnetic coils V. The magnetic coils The IV is installed on the mounting frame, the magnetic coil III and the magnetic coil V are installed on the rotor and are respectively located on the axial front and rear sides of the magnetic coil IV, and the magnetic coil IV has an axial gap with the magnetic coil III and the magnetic coil V; and the said The minimum value of the axial gap between the magnetic coil IV and the magnetic coil III and the magnetic coil V is greater than the maximum axial amplitude generated by the radial runout of the main shaft at the installation of these three coils, and the maximum value satisfies the requirements of the magnetic coil IV and the magnetic coil III, The force between the magnetic coils V is not less than 50% of the force when the gap is zero.

In addition, in the above-mentioned method and device for actively suppressing the beating of the main shaft of a machine tool, the magnetic coil I, magnetic coil II, magnetic coil III, magnetic coil IV, and magnetic coil V may each be composed of several sub-coils, wherein each sub-coil The axes are perpendicular to the normal surface of the rotor and are arranged in a ring in a plane perpendicular to the axis of the main shaft to form magnetic coils. In the installed state, the center of the circle formed by the sub-magnetic coils passes through the axis of the main shaft. The sub-coils in the magnetic coil are connected in parallel and powered by a power supply. The magnetic coils are embedded in their respective brackets, and the brackets and the main shaft rotor or the main shaft installation frame are fixed through threaded connections.

In addition, the magnetic coil I, magnetic coil II, magnetic coil III, magnetic coil IV, and magnetic coil V may be provided with adjustable resistors for fine-tuning their current values.

The present invention has the following effects: 1. Due to the controllable force applied to the extension end of the main shaft rotor, the radial runout of the main shaft is suppressed, the cantilever beam structure at the rotor extension end is improved, and the rigidity of the main shaft system is improved; 2. Through A magnetic coil group installed at the extending end of the rotor controls the inclination caused by the radial runout of the main shaft and can also suppress the radial runout of the main shaft; 3. The magnetic coil is small in size, and the installation of this device does not need to change the original main structure of the main shaft, which is easy to install and Easy to maintain; 4. Because the electromagnetic force can be adjusted according to the actual runout error amplitude by adjusting the voltage value on the coil, it is easy to adjust and can ensure the long-term accuracy requirements of the spindle; 5. Since the installed magnetic coil group is in use The position and weight remain unchanged during the process, so the dynamic balance performance of the spindle system will not be changed during use; 6. Since the electromagnetic field distance is closer and the interaction force is greater, the radial runout is automatically suppressed, so no sensors and computers are needed. The complex control system composed of devices has low cost.

Description of drawings

Fig. 1 is a schematic cross-sectional structure diagram of a preferred embodiment of the active suppressing device for spindle vibration of a machine tool according to the present invention.

Fig. 2 is an implementation state of the active suppressing device for machine tool spindle vibration of the present invention. In this state, the spindle has no radial runout, and the resultant force of the spindle mounting frame on the spindle rotor is zero.

Fig. 3 is an implementation state of the active suppressing device for machine tool spindle vibration of the present invention. In this state, the spindle has radial runout, and the resultant force of the spindle mounting frame on the spindle rotor is not zero, and the resultant force suppresses the radial runout of the spindle.

Fig. 4 is an implementation state of the active suppressing device for spindle vibration of a machine tool according to the present invention. In this state, the spindle has no radial runout, and the resultant torque of the spindle mounting frame to the spindle rotor is zero.

Fig. 5 is an implementation state of the active suppressing device for machine tool spindle vibration of the present invention. In this state, the spindle has radial runout, and the spindle produces deflection. pendulum to suppress radial runout.

Fig. 6 is an implementation flow chart of the method for actively suppressing the vibration of the spindle of the machine tool according to the present invention.

Fig. 7 is another implementation flow chart of the method for actively suppressing the vibration of the spindle of the machine tool according to the present invention.

Label name in Fig. 1: 1, magnetic force coil I, 2, magnetic force coil II, 3, magnetic force coil III, 4, magnetic force coil IV, 5, magnetic force coil V, 6, magnetic force coil wire, 7, main shaft rotor, 8, main shaft Mounting frame, 9, main shaft bearing, 10, main shaft rotor brush pivot, 11, main shaft stator brush pivot, 12, magnetic coil power supply brush pair, 13, voltage power supply.

Fig. 2, label name in Fig. 3: 201, the active force of magnetic force coil I to magnetic force coil II, 61, magnetic force coil I support, 62, magnetic force coil II support.

Fig. 4, label name in Fig. 5: 202, the active force of magnetic force coil III to magnetic force coil IV, 203, the active force of magnetic force coil V to magnetic force coil IV, 63, magnetic force coil III support, 64, magnetic force coil IV support, 65 , Magnetic coil V bracket.

Names of symbols in Fig. 6 and Fig. 7: 301-311, method implementation steps.

Detailed ways

The method and device for actively suppressing the runout of the machine tool spindle mainly utilizes electromagnetic control technology and is applied inside the machine tool spindle, and utilizes the electromagnetic torque that changes with the radial runout amplitude and phase between the electromagnetic coil groups installed at appropriate positions in the spindle To suppress the radial runout of the spindle. The specific implementations of the method and device of the present invention will be described in detail below.

Fig. 6 and Fig. 7 are two flow charts of a preferred embodiment of the method for actively suppressing the vibration of the main shaft according to the present invention.

In Fig. 6, the active suppression method for spindle vibration of the present invention may include the following steps:

Step 301: The main shaft as shown in FIG. 1 starts to run, no radial runout occurs, the main shaft is at the initial position, and the gap between the axial magnetic coils (III, IV, V) and the radial magnetic coils (I, II) is uniform.

Step 302: Since the gaps between coil IV, coil III and coil V in the axial magnetic coil are uniform, and the interaction force (202, 203) is also uniform, the moment of coil III and coil V on coil IV is zero.

Step 303: When the main shaft runs at high speed, the main shaft produces a large radial runout, which causes the main shaft to yaw. Then, in the axial magnetic coil, the gap between coil IV, coil III and coil V changes, and the gap is no longer uniform.

Step 304: Due to the change of the gap between the coil IV, the coil III and the coil V, the uneven gap causes the mutual force (202, 203) to be uneven, and a torque is generated.

Step 305: The generated torque value is positive to the amplitude of the radial runout of the main shaft at the installation position of the magnetic coil IV, and the direction is opposite to the direction of the radial runout.

Step 306: The torque restrains the radial runout of the main shaft, so that the main shaft tends to the initial position.

The above steps 301 to 306 are repeatedly executed during the running of the main shaft until the main shaft stops running.

In Fig. 7, it is the steps of another implementation case of the active suppression method of the main shaft vibration of the present invention:

Step 301: The main shaft as shown in FIG. 1 starts to run, no radial runout occurs, the main shaft is at the initial position, and the gap between the axial magnetic coils (III, IV, V) and the radial magnetic coils (I, II) is uniform.

Step 307: Since the gap between the coil I and the coil II is uniform in the radial magnetic coil, the interaction force (201) is also uniform, so the resultant force of the coil I to the coil II is zero.

Step 308: The spindle rotates at a high speed to generate a large radial runout, and the gap between the coil I and the coil II in the radial magnetic coil changes, and the gap is no longer uniform.

Step 309: Since the gap between the coil I and the coil II changes, the uneven gap causes the mutual force (201) to be uneven, and the resultant force generated is not zero.

Step 310: The value of the resultant force generated is positive to the amplitude of the radial runout of the main shaft at the installation position of the magnetic coil I, and the direction is opposite to the direction of the radial runout.

Step 311: The resultant force restrains the radial runout of the main shaft, so that the main shaft tends to the initial position.

The above step 301 and step 307 to step 311 are repeatedly executed during the running of the main shaft until the main shaft stops running.

The active suppression method of the main shaft vibration of the present invention shown in Fig. 6 and Fig. 7 can be implemented at the same time, and can also be implemented separately for the case of radial runout. The implementation case shown in Figure 6 can be used alone when the radial runout causes the spindle deflection, and the implementation case shown in Figure 7 can be used alone when the radial runout only causes position deviation without deflection. When it happens, the two implementation cases of appeal can be used at the same time.

Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5 are a specific implementation case of the main shaft vibration active suppressing device of the present invention, which includes magnetic force coils (II, IV) on the extended end of the main shaft rotor, Magnetic coil (I, III, V) and voltage power supply 13, it is characterized in that:

First of all, there is a radial gap of a certain distance between the magnetic coil on the spindle mounting frame (hereinafter referred to as coil I) and the magnetic coil at the extension end of the spindle rotor (hereinafter referred to as coil II), and the radial gap is determined according to the following steps:

A. Determine the minimum value, measure the radial runout of the main shaft when the machine tool that is not installed with the device of the present invention is in operation, and calculate the radial amplitude of the runout at the position to be installed. The gap minimum should be 2 to 3 mm larger than this magnitude.

B. The maximum value is determined. Take out a sub-coil from coil I and coil II respectively, and measure the interaction force when the distance between the two is zero. This force is the maximum force that can be produced by the two. Increase the distance between the two until the interaction force is only 50% of the maximum force, then this distance can be used as the maximum value of the gap.

C. According to the diameter of the main shaft rotor and the inner diameter of the main shaft installation frame, select a suitable coil support so that the gap between coil V and coil II is between the maximum value and the minimum value.

The sub-coils in the two coil groups are arranged in a ring, and the coil I and the coil II are concentric, the coil II is in the coil I, and the two coil groups are in the same plane, and the two coil groups are energized through the control circuit, then the position of the two coil groups An interaction force is generated between the coils of the corresponding parts. Under the ideal condition of no radial runout of the main shaft, when the radial distance of the two coil groups is equal everywhere, the resultant force of coil I to coil II is zero, that is, the force exerted by the mounting frame on the rotor extension is zero. When the radial runout of the main shaft occurs, the position of the axis of the rotor extension end and the mounting frame changes, the radial distance between coil I and coil II is no longer equal everywhere, and the interaction force corresponding to the coil increases when the distance decreases, and the distance increases. If it is large, it will decrease. The resultant force of coil I to coil II is not zero. The magnitude of the resultant force is positive to the size of the radial runout value and points to the opposite direction of the radial runout of the main shaft. Therefore, the resultant force can effectively restrain the resistance against the main shaft. Radial runout. Control the voltage value on the coil group and adjust the voltage according to the induction ability of the coil to ensure that when the coil I and the coil II are concentric, the resultant force of the coil I on the coil II is zero.

Secondly, a magnetic coil III (hereinafter referred to as coil III) and a magnetic coil V (hereinafter referred to as coil V) are provided on the spindle mounting frame, and a magnetic coil IV (hereinafter referred to as coil IV) is provided on the rotor extension. The inner coils of coil III, coil IV and coil V are all arranged in a ring, and the centers of the three magnetic coils are on the same straight line, and the straight line is perpendicular to the circular surface of each coil group, that is, the three coils are stacked, and the stacking order is as follows: From top to bottom are: Coil V, Coil IV, Coil III. There is a certain gap between the coil V and the coil IV, and the same axial gap between the coil IV and the coil III. The three coils are energized by the voltage source, and both the coil III and the coil V will exert force on the coil IV. The above-mentioned axial clearance can be determined by referring to the method of radial clearance. In the case of no radial direction of the main shaft, the axial gap between coil III and coil IV and the axial gap between coil IV and coil V are equal everywhere, and the resultant force of the main shaft mounting frame on the rotor is zero. When the spindle runs out radially, coil IV tilts, and the axial gap between it and coil III and coil V becomes uneven, and the resultant force of the mounting frame on the rotor is not zero. The magnitude of this force is related to the inclination angle caused by the runout In a positive relationship, and pointing to the opposite direction of the tilt direction, the force forms a torque on the rotor to suppress radial runout.

At the same time, according to the power and rotational speed of the main shaft, the output voltage of the voltage power supply 13 is adjusted to change the force between the magnetic coil groups. The greater the spindle power and the higher the speed, the greater the electromagnetic torque required to suppress the radial runout, which can be achieved by increasing the voltage value of the voltage power supply.

The electromagnetic coils I, III, V on the mounting frame are directly connected to the power supply through wires; the electromagnetic coils II, IV on the rotor are connected to the brush pair 12 arranged in the main shaft through the magnetic coil wires 6 so as to be connected to the voltage power supply 13.

At the same time, magnetic coil I, magnetic coil II, magnetic coil III, magnetic coil IV, and magnetic coil V all contain adjustable resistors for fine-tuning their current values. Each sub-coil in the magnetic coil I ^- V is connected in series with an adjustable resistor, and the resistance value of the adjustable resistor is adjusted to fine-tune the current value of the sub-coil connected in series with it, thereby fine-tuning the magnetic field intensity generated by the sub-coil. For each magnetic coil, the adjustable resistance of its internal sub-coils can be adjusted so that the magnetic field intensity generated by its internal sub-coils is consistent, and the symmetrical distribution of the magnetic field intensity in the circumferential direction of the magnetic coils is realized. The symmetrically distributed magnetic field is beneficial to the stability of the machine tool spindle vibration active suppressing device of the present invention during operation.

The above is only a preferred embodiment of the method and device for actively suppressing runout of the machine tool spindle involved in the present invention, but the implementation scope of the present invention is not limited to this example.

Claims (4)

1, a kind of pulsation of machine tool main shaft initiatively suppresses method, it is characterized in that: on spindle rotor and main shaft scaffold, electromagnetic force coil is installed respectively, and makes it keep certain interval, form radial magnetic force coil groups and axial magnetic coil group respectively, wherein:

(a), the maximum radial amplitude that produces in this group coil installation place greater than the main shaft circular runout of the minimum value that makes described radial magnetic force coil groups gap, when maximum value satisfies the active force that makes between this group magnetic coil and is not less than this gap and is zero 50% of active force; When main shaft generation circular runout, radial magnetic force coil groups gap changes, the electromagnetism that produces forward and main shaft main shaft circular runout amplitude is made a concerted effort, and this electromagnetism resultant direction is opposite with the direction of beating, and it applies with the spindle rotor external part and makes main axis jerking be inhibited;

When (b), simultaneously, the maximum axial amplitude that the minimum value that makes described axial magnetic coil group gap produces in this group coil installation place greater than the main shaft circular runout, maximum value satisfy the active force that makes between this group coil and are not less than this gap and are zero 50% of active force; When main shaft causes the circular runout of spindle swing, axial magnetic coil group gap changes, produce forward in the electromagnetic torque of main shaft circular runout amplitude, this electromagnetic torque direction is opposite with swaying direction, and it puts on the spindle rotor external part makes main axis jerking be inhibited.

2, a kind of pulsation of machine tool main shaft active restraining device, it is characterized in that: this device is made up of two groups of magnetic coil groups and a voltage source, wherein:

(a), first group of magnetic coil group is the radial magnetic force coil groups, stretch out magnetic coil I (1) on the least significant end and magnetic coil II (2) that be installed in scaffold (7) on relative with it with the position and form by being installed in rotor (6), magnetic coil I (1) and magnetic coil II (2) radially have radial clearance; And when the maximum radial amplitude that the minimum value of described magnetic coil I (1) and magnetic coil II (2) radial clearance produces in these two coil installation places greater than the main shaft circular runout, maximum value satisfy the active force that makes between magnetic coil I (1) and magnetic coil II (2) to be not less than this gap are zero 50% of active force;

(b), second group of magnetic coil group is axial magnetic coil group, be positioned between first group of magnetic coil group and the rotor external part bearing (8), it is made up of magnetic coil III (3), magnetic coil IV (4), magnetic coil V (5), magnetic coil IV (4) is installed on the scaffold (7), magnetic coil III (3) and magnetic coil V (5) are installed in the both sides, axial front and back that magnetic coil IV (4) was gone up and laid respectively to rotor (6), and magnetic coil IV (4) and magnetic coil III (3), magnetic coil V (5) have axial clearance; And when the maximum axial amplitude that the axial clearance minimum value of described magnetic coil IV (4) and magnetic coil III (3), magnetic coil V (5) produces in these three coil installation places greater than the main shaft circular runout, maximum value satisfy the active force that makes between magnetic coil IV (4) and magnetic coil III (3), magnetic coil V (5) to be not less than this gap are zero 50% of active force.

3, pulsation of machine tool main shaft active restraining device according to claim 2, it is characterized in that: described magnetic coil I (1), magnetic coil II (2), magnetic coil III (3), magnetic coil IV (4), magnetic coil V (5) are made up of each free plurality of sub coil; Wherein, each subcoil axis normal circularizes arrangement in rotor (6) normal plane in the plane vertical with the spindle axis line, constitutes magnetic coil, and during installment state, the spindle axis line is crossed in the center of circle of being somebody's turn to do the circle that is arranged in by sub-magnetic coil; For being connected in parallel, and by the power supply power supply, magnetic coil is embedded in separately the support on the subcoil circuit in the magnetic coil, and support and spindle rotor (6) or main shaft scaffold (7) are fixing by being threaded.

4, according to right 2 or 3 described pulsation of machine tool main shaft active restraining devices, it is characterized in that: described magnetic coil I (1), magnetic coil II (2), magnetic coil III (3), magnetic coil IV (4), magnetic coil V (5) contain the adjustable resistance that is used for finely tuning its current value.

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