JP6415623B2 - Control method and control device for tapping - Google Patents

Description

  The present invention is a so-called synchronous tapping process that performs tapping on a workpiece by synchronizing the rotation operation of a tap mounted on a rotating spindle driven by a motor and the relative feed operation of the tap with respect to the workpiece in the rotation axis direction. The present invention relates to a control method and a control apparatus.

  Winding switching motors are widely used as spindle motors for machine tools. A low-speed winding and a high-speed winding are provided inside the winding switching motor, and they are switched according to the rotational speed commanded from the machining program to the main shaft. The main shaft motor can drive the main shaft at a low speed and a high torque with a low speed winding and a high speed and a low torque with a high speed winding. It is well known that the main shaft can be driven at low speed and high torque or at high speed and low torque by a mechanical two-stage transmission connected to the output shaft of the main shaft motor instead of the winding switching motor. By the way, synchronous tapping is widely performed using a machine tool having a winding switching motor.

  Patent Document 1 discloses a screw machining apparatus that efficiently performs synchronous tapping. However, the spindle motor of the machine tool of Patent Document 1 is not a winding switching motor and is not connected to a two-stage transmission.

Japanese Patent No. 3136851

  When performing synchronous tapping using a machine tool with a coil switching motor, the machining program creator wants to increase the spindle rotation speed as much as possible to shorten the machining time and increase the spindle command rotation speed. Tend. However, increasing the rotation speed of the spindle does not simply shorten the tapping time. The tap processing time depends on various conditions such as a tap processing distance. However, it is difficult for the machining program creator to accurately determine in a short time whether the rotation speed on the low-speed winding side or the rotation speed on the high-speed winding side is advantageous from the viewpoint of shortening the machining time. Met. For this reason, it is presumed that there have been many cases where disadvantageous selection has been made from the viewpoint of machining time.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tap machining control method and a control device capable of reducing machining time in synchronous tap machining.

In order to achieve the above-described object, according to the present invention, rotation of a tap mounted on a rotating spindle driven by a motor having a built-in speed change means that performs low-speed high-torque driving and high-speed low-torque driving by switching windings. In the tap processing control method for performing tap processing on the work by synchronizing the operation and the relative feed operation of the tap in the rotation axis direction with respect to the work, at each predetermined step when using the low speed winding and the high speed winding. Acceleration, acceleration time, number of rotations during acceleration, acceleration during deceleration, deceleration time, number of rotations during deceleration, number of rotations during acceleration and number of rotations during deceleration the step of creating a table that associates each value of acceleration and deceleration rotation number is the sum of the advance, prior to tapping, machining distance of the tap, low speed and high torque driving and the high-speed low torque to the parallel beauty Step of reading the maximum speed for each of the dynamic, based on the read data and tables created, and calculates the respective shortest tapping time for low speed high torque during driving and high-speed low-torque drive to one of the tap hole There is provided a tapping control method including a step and tapping a tapped hole at a rotation speed with a shorter calculated tapping time.

Furthermore, in order to achieve the above-described object, according to the present invention, a tap mounted on a rotating spindle driven by a motor incorporating a speed change means for performing low speed high torque drive and high speed low torque drive by switching windings. and rotation of, by synchronizing the relative feeding operation of the rotational axis of the tap relative to the workpiece, the tapping control apparatus for controlling tapping in performing tapping on the workpiece, the slow winding and fast previously prepared Acceleration during acceleration, acceleration time, number of rotations during acceleration, acceleration during deceleration, deceleration time, number of rotations during deceleration, as well as acceleration at each rotation speed of the motors arranged in predetermined steps when using windings, and stores the table showing the correspondence of the values of acceleration and deceleration rotation number is the sum of the rotation number during deceleration rotation number during acceleration prior to tapping, the processing of the tap Away, maximum speed you store Loading the Symbol憶部for each low-speed high torque drive and high-speed low-torque drive to the parallel beauty, on the basis of the read and the table storage unit data, low-speed high torque for one tap hole A tapping process comprising: an arithmetic processing unit that calculates the shortest tapping time for driving and high-speed low-torque driving, and instructs tapping for a tapped hole at the shorter rotation speed of the calculated tapping time. A control device is provided.

  According to the present invention, even if there are a large number of tapping locations with different diameters and depths, the rotation speed of the spindle that can obtain the shortest machining time for all tapping locations is troubled by the machining program creator. It is possible to make an accurate determination without any problem. Actually, the difference in machining time between low-speed and high-torque driving and high-speed and low-torque driving is often 1 second or less, but even such a small difference has many tapping points. For workpieces such as cylinder blocks of automobile engines, a great effect of shortening the machining time can be produced.

It is a front view of the spindle head of the machine tool which implements the tap machining control method according to the embodiment of the present invention. It is a graph which shows typically the time change of the rotational speed by the low-speed winding of a spindle motor, and the high-speed winding at the time of performing synchronous tap processing to a certain tap hole. It is a flowchart of the control method of the tap process by embodiment of this invention. It is a front view of the spindle head of another machine tool that implements the tap machining control method according to the embodiment of the present invention. It is a related line figure of torque and rotation speed of a spindle motor in other embodiments of the present invention. It is a related line figure of the output of a spindle motor and rotation speed in other embodiments of the present invention. It is a related line figure of the acceleration and rotation speed of principal axis rotation in other embodiments of the present invention.

Hereinafter, a tap processing control method according to an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a schematic front view of a spindle head 10 of a vertical machine tool capable of implementing a tap machining control method according to an embodiment of the present invention. A spindle motor 14 that rotates the spindle 12 in the _CS axis direction is built in the spindle head 10. A tap 18 is attached to the tip of the main shaft 12. The main shaft motor 14 is a winding switching motor, and its winding 16 is composed of a switchable low-speed winding and a high-speed winding. The low speed winding and the high speed winding are the speed change means in the present invention. If a low-speed winding is used, a relatively low-speed high-torque drive is possible, and if a high-speed winding is used, a relatively high-speed low-torque drive is possible. The machine tool also includes a Z-axis drive device (not shown) including a Z-axis feed motor (not shown) that drives the spindle head 10 in the Z-axis direction.

  The spindle motor 14 and the Z-axis feed motor receive a command from the control device and perform rotation in the Cs-axis direction and Z-axis direction in response to an instruction from the control device in order to perform synchronous tapping on the pilot hole 19 formed in the workpiece W The feed is controlled so as to be synchronized with the feed. In the present embodiment, the control of the Z-axis feed motor at the time of synchronous tapping is performed in a known manner, and thus the description thereof will be omitted, and a control method of the spindle motor 14 will be described.

FIG. 2 shows the rotation speed V of the spindle motor 14 when the synchronous tapping (hereinafter simply referred to as “tapping”) is performed on a single tapped hole. It is a graph which shows a time change typically. In the figure, the ultimate rotational speed V _L of the low-speed winding and the ultimate rotational speed V _H of the high-speed winding are shown. These reaching rotation speeds V _L and V _H are maximum values of the rotation speed during processing of a certain tapped hole, and can be command rotation speeds. The ultimate rotational speed V _L of the low-speed winding takes a value equal to or lower than a predetermined winding switching speed Vs, and the ultimate rotational speed V _H of the high-speed winding takes a value exceeding the winding switching speed Vs.

  In FIG. 2, the trapezoidal wave shows the case where the low-speed winding is used, and the triangular wave shows the case where the high-speed winding is used. However, even when a low-speed winding is used, there is a case of a triangular wave, and even when a high-speed winding is used, there is a case of a trapezoidal wave. Whether it is a triangular wave or a trapezoidal wave is determined by conditions such as the tapping distance.

It can be seen from FIG. 2 that low-speed high-torque driving with a low-speed winding and high-speed low-torque driving with a high-speed winding are possible. Further, FIG. 2 shows that only the high-speed winding is used to reach the ultimate rotational speed V _H of the high-speed winding from the speed 0. In other words, it can be understood that the low-speed winding is used until the winding switching speed Vs in the middle and the high-speed winding is not switched thereafter.

In FIG. 2, the rotational speed of the forward path of the tapping process is shown on the plus side, and that of the return path is shown on the minus side. The forward and backward waveforms in FIG. 2 are point symmetric with respect to the point BP. The point BP indicates a position where the rotational speed is 0, and therefore corresponds to the lowest value of the stroke of the tap 18. The acceleration times Ta _L and Ta _H and the deceleration times Td _L and Td _H in FIG. 2 are not equal, and the acceleration times Ta _L and Ta _H are shorter than the deceleration times Td _L and Td _H. This is true for both low speed and high speed windings. Further, the total area of the trapezoidal or triangular forward and return paths in FIG. 2 indicates the reciprocating machining distance of the tap 18 or the total number of rotations Rt at the time of tapping. The total number of rotations Rt of the tap 18 can be calculated from the machining distance and pitch of the tap 18 read from the machining program. Here, the machining distance of the tap 18 means a movement distance of the tap 18 in the Z-axis direction while the Z-axis feed axis is performing synchronous feed until the tip of the tap 18 contacts the surface of the workpiece W. The movement distance is also included.

In the example shown in FIG. 2, the processing time TL for the low-speed winding is shorter than the processing time TH for the high-speed winding. Therefore, for the tap hole assumed in FIG. 2, it is advantageous from the viewpoint of shortening the machining time to command the spindle motor 14 as the rotational speed _VL reached by the low-speed winding as the rotational speed of the tap 18. . However, whether the processing time when using the low-speed winding or the high-speed winding is shortened depends on the acceleration characteristics of the motor used, the length of the processing distance of the tap 18, that is, the total number of rotations Rt. It depends on a plurality of conditions such as the maximum rotation speed when each winding of the motor is used and the allowable peripheral speed of the tap 18. The method according to the embodiment of the present invention can determine the spindle rotation speed that produces the shortest machining time in consideration of the plurality of conditions.

  Hereinafter, a tapping process control method according to an embodiment of the present invention will be described with reference to a flowchart of FIG. 3 showing an example thereof. This control method is implemented by a tap machining control device prepared as a component of a machine control device of a machine tool.

  The tapping processing control device first reads NC parameters (step S10). The NC parameters read here are the maximum rotation speed Vs for the low-speed winding and the maximum rotation speed Vmax for the high-speed winding, and the respective accelerations αa and αd when using the low-speed and high-speed windings. The maximum rotation speed Vs for the low-speed winding is also called a winding switching speed Vs.

Next, the acceleration time Ta and the deceleration time Td for each rotational speed V _i (i is an integer from 1 to n) arranged in steps of, for example, about 10 [rev / min] when using the low-speed and high-speed windings. And the number of acceleration / deceleration rotations Rg is calculated (step S20). Acceleration time Ta and the deceleration time Td and deceleration rotation number Rg is calculated based on the known acceleration αa or αd per revolution velocity V _i. The calculation results are stored as a table in the tapping process control device. Tables 1 and 2 are tables created in this way, where Table 1 is a table for a low-speed winding and Table 2 is a table for a high-speed winding. Vs in Table 1 represents a winding switching speed, that is, a maximum rotation speed set when a low-speed winding is used, and Vmax in Table 2 represents a maximum rotation speed of the high-speed winding.

  By the way, in the present embodiment, the acceleration of the spindle motor 14 is not necessarily strictly constant because acceleration / deceleration is performed using the maximum output (torque) that can be generated by the motor. , And there is a delay time with respect to the speed command. As described above, the acceleration time is obtained based on the acceleration data obtained in advance for each rotational speed of about 10 [rev / min], for example. Ta, deceleration time Td, and number of acceleration / deceleration rotations Rg are calculated and stored as a table in the tap machining control device. As a result, the accuracy of calculation of the number of acceleration / deceleration rotations Rg is increased and the overall processing time can be shortened.

  Next, tool data and a machining program are read (step S30). Specifically, the diameter, machining distance, pitch, and allowable peripheral speed of the tap 18 are read from the machining program.

  Next, the number of rotations required for processing, that is, the total number of rotations Rt is calculated from the processing distance and pitch of the tap 18 (step S40). The total number of rotations Rt originally corresponds to the sum of the forward and return areas in the graph of FIG. 2, but the forward and return areas are symmetrically equal with respect to the point BP. This will be described as the total number of rotations Rt.

Next, each of the arrival rotational speed V _L of the low speed winding and a high speed winding used _to determine the V _H (step S50). More specifically, here, the maximum values of the possible rotation speeds V _L and V _H are determined. The ultimate rotational speeds _VL and _VH are determined by the magnitude relationship between the total number of rotations Rt for the low-speed winding and the number of acceleration / deceleration rotations Rgs for the coil switching speed, and the total number of rotations Rt and the maximum rotational speed for the high-speed winding. It is determined by the following methods (1) to (4) according to the magnitude relationship with the rotation number Rgmax with respect to Vmax.

First, the maximum possible rotational speed V _L when using a low-speed winding is determined.
(1) When Rt ≧ Rgs In this case, the ultimate rotational speed V _L is determined to be the smaller of the winding switching speed Vs and the allowable rotational speed Vc of the tap 18. Here, the allowable rotational speed Vc of the tap 18 is a value determined based on the allowable peripheral speed of the tap 18.
(2) Rt <reaches rotational speed _{V L} of this case Rgs is determined to smaller allowable rotation speed Vc of the rotational speed _{V i} and the tap 18 of Table 1.
Therefore, in order to select V _i in Table 1, the acceleration / deceleration rotation frequency Rg _iL in Table 1 that satisfies the total rotation frequency Rt is selected. More particularly, selected from Table 1 closest deceleration rotation number Rg _iL the total rotation number Rt or less and the total number of rotations Rt. Then, the arrival speed V _L when the smaller allowable rotation speed Vc of the rotational speed V _i and the tap 18 corresponding to the acceleration and deceleration rotation number Rg _iL selected slow winding. In this case, the selected number of acceleration / deceleration rotations Rg _iL does not normally coincide with the required total number of rotations Rt, so it is preferable to finely correct the ultimate rotation speed _VL in consideration of the difference.

Next, the maximum value of the reachable rotational speed V _H when using the high-speed winding is determined.
(3) In the case of Rt ≧ Rgmax In this case, the reached rotation speed V _H is determined to be the smaller of the maximum command rotation speed Vmax and the allowable rotation speed Vc of the tap 18.
Here, as shown in Table 2, Rgmax is the number of acceleration / deceleration rotations with respect to the maximum rotation speed Vmax.
(4) Rt <reaches rotational speed _{V H} of the main shaft 12 in this case when the Rgmax is determined to smaller allowable rotation speed Vc of Table 2 rotational speed _{V i} and the tap 18.
Therefore, in order to select V _i in Table 2, the acceleration / deceleration rotation frequency Rg _iH in Table 2 that satisfies the total rotation frequency Rt is selected. More specifically, an acceleration / deceleration rotation number _RgiH that is equal to or less than the total rotation number Rt and is closest to the total rotation number Rt is selected from Table 2. Then, the arrival speed V _H when the smaller allowable rotation speed Vc of the rotational speed V _i and the tap 18 corresponding to the selected acceleration and deceleration rotation number Rg _iH fast winding. In this case, the selected number of acceleration / deceleration rotations Rg _iH usually does not coincide with the required total number of rotations Rt. Therefore, it is preferable to finely correct the ultimate rotation speed V _H in consideration of the difference.

Next, from the determined rotational speeds V _L and V _{H of} the determined low-speed winding and high-speed winding, acceleration times Ta _L and Ta _H corresponding thereto, deceleration times Td _L and Td _H , and the total number of rotations Rt The machining time TL for the low-speed winding and the machining time TH for the high-speed winding are calculated (step S60).

  The calculated machining time TL and ТH may be displayed on a display device of the machine control device, for example. The machining times TL and ТH obtained here are the times of the forward path, but if the total time of the forward path and the return path is necessary, the obtained time may be doubled.

Next, a comparison is made between the calculated machining time TL for the low-speed winding and the machining time TH for the high-speed winding (step S70), and if the machining time TL for the low-speed winding is less than or equal to the machining time TH for the high-speed winding. For example, the ultimate rotational speed _VL by the low-speed winding determined in step S50 is sent out as the main spindle rotational speed (step S80). Otherwise, the machining time TH by the high-speed winding is less than the machining time TL by the low-speed winding. if the arrival rotational speed V _H by high winding determined in step S50 is sent as a spindle rotation speed (step S90). In the present embodiment, the selected ultimate rotational speed V _L or V _H is sent to the machining program, and the machining program is rewritten. As a result, tapping is performed at the spindle rotation speed with the shorter tapping time. However, an embodiment in which the machining program is not rewritten only by displaying information on the selected ultimate rotational speed V _L or V _H is also possible in the present invention.

  According to the tap machining control method of the present embodiment, even if there are a large number of tap machining locations having different diameters and depths, the rotational speed of the spindle 12 that provides the shortest machining time for all the tap machining locations is machined. It becomes possible to make an accurate determination without bothering the program creator. Actually, the difference in machining time between the low-speed winding and the high-speed winding is often 1 second or less, but even such a small difference has many tapped portions, for example, an automobile engine. A great effect can be produced for a workpiece W such as a cylinder block.

In the foregoing embodiments, for the purpose of shortening the processing time, had been prepared as Tables 1 and 2 to calculate the acceleration and deceleration rotation number Rg like every rotational speed V _i of the predetermined step interval, In the present invention, if the acceleration data of each winding of the motor is determined, other embodiments for calculating the shortest machining times TL and TH of each winding without preparing such a table are possible. It will be understood.

Another embodiment for calculating the machining times TL and TH will be described. FIG. 5 is a relationship diagram between the torque and the rotation speed of the spindle motor of a typical machine tool, and FIG. 6 is a relationship diagram between the output of the spindle motor and the rotation speed. These diagrams are known in machine tools. The load inertia I [Kgm ² ] acting on the spindle motor when the maximum tap is attached to the spindle is also a known constant value. If the torque at an arbitrary spindle speed Vn [rev / min] is t [Nm], the output is P [W], and the acceleration is α [rev / s ² ], the following two equations are established.
I · α = t (1)
t = 60 · P / Vn (2)
From the formulas (1) and (2), α = t / I = 60 · P / I · Vn (3)
It becomes.
FIG. 7 shows the relationship between the acceleration and the spindle rotation speed in a diagram using FIG. 5 or FIG. 6 and equation (3).

  In each of the diagrams of FIGS. 5 to 7, the rotation speed when the diagram of the low-speed winding and the diagram of the high-speed winding intersect is set as the winding switching speed Vs. In FIG. 7, the spindle is rotated at an acceleration along the acceleration diagram of the low-speed winding in the region where the rotational speed is up to Vs, and at an acceleration along the acceleration diagram of the high-speed winding in the region where the rotational speed exceeds Vs. It is advantageous in terms of machining time to rotate the main shaft. That is, it is advantageous in terms of machining time to accelerate with the maximum output characteristic of the spindle motor. Using the acceleration along the acceleration diagram of each winding in FIG. 7 and the spindle rotation speed, machining when machining with a low-speed winding is schematically performed as shown in FIG. The time TL and the machining time TH when machining with high-speed winding are calculated. At this time, the area surrounded by the broken line of the forward path of each winding and the time T axis on the horizontal axis corresponds to the machining distance. For convenience, a value obtained by inverting the sign of acceleration is used for the deceleration. The return path is assumed to be the shape of the vertical object, and the values of the machining times TL and TH are calculated. The winding with the smaller calculated machining time TL, TH is selected. However, the allowable rotational speed Vc determined based on the allowable peripheral speed of the tap must not be exceeded. Thus, the acceleration can be obtained from the relationship between the spindle torque or the spindle output and the load inertia, and the shortest machining times TL and TH of each winding can be calculated using the acceleration.

  In the description of step S10 in FIG. 3, it has been described that one of the NC parameters to be read first includes the respective accelerations when using the low-speed and high-speed windings. Normally, the NC parameter is adjusted to the upper limit of the spindle motor output by adjusting the actual machine. Decide with a margin. Instead of this, the respective accelerations when using the low-speed and high-speed windings of the NC parameter can be calculated from the relationship between the spindle torque or the spindle output and the load inertia, as described in other embodiments.

  FIG. 4 shows a schematic front view of a spindle head 20 of another vertical machine tool capable of performing the tap machining control method according to the embodiment of the present invention. In the machine tool of this example, a winding switching motor is not used. Instead, the power of the external spindle motor 24 is transmitted to the spindle 22 via a mechanical two-stage transmission 26. A tap 18 is attached to the tip of the main shaft 22. The two-stage transmission 26 includes a switchable low speed gear 26a and a high speed gear 26b. The main shaft 22 is driven at low speed and high torque by the low speed gear 26a, and is driven at high speed and low torque by the high speed gear 26b. As described above, the low speed gear 26a and the high speed gear 26b correspond to the low speed winding and the high speed winding of the winding switching motor 16 in the above description. Omitted.

The present invention can also be implemented as a tapping process control device.
A tap machining control device (not shown) according to an embodiment is configured to rotate a tap mounted on a rotary spindle driven by a winding switching motor that can switch between a low speed high torque drive and a high speed low torque drive, Processing control when performing tap processing on a workpiece is performed in synchronization with the relative feed operation of the tap in the rotation axis direction.

Prior to tapping, the tap machining control device according to this embodiment includes a tapping distance, an allowable circumferential speed of the tap, acceleration α during low speed high torque driving and high speed low torque driving, and low speed high torque driving and high speed. A reading storage unit is provided for reading and storing the maximum rotation speeds Vs and Vmax for each of the low torque drives. Furthermore, the tapping process control device calculates the shortest tapping time TL and TH at the time of low speed high torque driving and high speed low torque driving with respect to one tapped hole based on the read data, and the calculated tapping process. An arithmetic processing unit is provided for instructing tapping with respect to the tapped hole at the rotation speed V _L or V _H which is the shorter of the times TL and TH.

Arithmetic processing unit, the maximum rotational speed Vs of the read acceleration data α and windings, the Vmax, for example, 10 [rev / min] of about acceleration time Ta and the deceleration time for each rotational speed V _i arranged in step Td and the number of acceleration / deceleration rotations Rg are calculated, the above-described Table 1 and Table 2 are created, and the data of the tables are read and stored in the storage unit. Further, the arithmetic processing unit may determine the ultimate rotational speed V _L of the low-speed winding and the ultimate rotational speed V _H of the high-speed winding in the manner described above in order to calculate the shortest tapping time TL and TH. It is configured.

10 Spindle head 14 Spindle motor 16 Winding 18 Tap Rt Total number of rotations Ta _L Low speed winding acceleration time Ta _H High speed winding acceleration time Td _L Low speed winding deceleration time Td _H High speed winding deceleration time Vs Winding Switching speed _VL Low speed winding reached speed V _H High speed winding reached speed TL Low speed winding machining time TH High speed winding machining time

Claims (5)

Rotation operation of a tap mounted on a rotating spindle driven by a motor with a built-in speed change means that performs low-speed high-torque drive and high-speed low-torque drive by winding switching , and relative feed operation in the rotation axis direction of the tap with respect to the workpiece In the tap processing control method for performing the tap processing on the workpiece,
Acceleration during acceleration, acceleration time, number of rotations during acceleration, acceleration during deceleration, deceleration time, during deceleration when using low-speed winding and high-speed winding for each of the motors arranged in a predetermined step A step of preparing a table in advance corresponding to each value of the number of rotations of acceleration and deceleration and the number of acceleration / deceleration rotations that is the sum of the number of rotations during deceleration
Prior to tapping, machining distance of the taps, the step of reading the maximum speed for each of the low-speed high-torque drive of the high-speed low-torque drive to the parallel beauty,
Based on the read data and the table mentioned above created, the step of calculating the time of the low-speed high torque drive to one of the tapped hole and the respective shortest tapping time for the high-speed low-torque drive, and calculated the tapping A tapping process control method comprising: tapping the tapped hole at a rotational speed with a shorter time. The tap machining control method according to claim 1, wherein the machining distance of the tap is read from a machining program. 3. The tap machining control method according to claim 1, further comprising a step of displaying a shortest tap machining time for each of the low-speed high-torque driving and the high-speed low-torque driving calculated in the calculating step. . When the calculated rotation speed of the shorter tapping time is different from the command rotation speed of the machining program, the machining program is rewritten so that the calculated rotation speed of the shorter tapping time becomes the command rotation speed. The control method of the tap process as described in any one of Claims 1-3 . Rotation operation of a tap mounted on a rotating spindle driven by a motor with a built-in speed change means that performs low-speed high-torque drive and high-speed low-torque drive by winding switching , and relative feed operation in the rotation axis direction of the tap with respect to the workpiece In the tapping process control device that controls tapping when performing tapping on the workpiece,
Acceleration, acceleration time, number of rotations during acceleration, acceleration during deceleration, deceleration time for each rotation speed of motors arranged in a predetermined step when using low-speed winding and high-speed winding created in advance In addition, a table that associates each value of the number of rotations during deceleration and the number of acceleration / deceleration rotations that is the sum of the number of rotations during acceleration and the number of rotations during deceleration is stored, and the tap processing is performed prior to the tap processing. distance, SL you store reads the maximum speed for each of the low speed and high torque drive to the high speed low torque drive to the parallel beauty憶部,
On the basis of the read and the table of the storage unit data, and calculates the respective shortest tapping time of the low speed high torque during driving and during the high-speed low-torque drive to one tap hole,
A tapping control apparatus comprising: an arithmetic processing unit that instructs tapping with respect to the tapped hole at a rotation speed with a shorter calculated tapping time.

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