JPS6153176B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a workpiece rotation control device in a generating gear cutting machine such as a hobbing machine.

Generating gear cutting machines that are generally employed include hobbing machines that use a hob as a rotating tool, gear cutting machines that use a pinion-shaped rotating tool, and gear cutting machines that use a rack-shaped linear displacement tool. In a generating gear cutting machine, a rotating tool, i.e. a hob or pinion type tool, is fed parallel to the axis of the workpiece and rotates at the same time. In the case of a rack-type linear displacement tool, the tool is fed parallel to the axis of the workpiece and at the same time linearly displaced. The workpiece rotates in synchronization with the operation of the tool, so-called generating gear cutting is performed, and gear teeth are machined onto the workpiece. In addition, as is well known, when machining the teeth of a spur gear on a workpiece, the rotation of the workpiece is controlled only in relation to the rotation or linear displacement of the tool, and when machining the teeth of a helical gear In this case, the rotation of the workpiece is controlled in relation to both the rotation or linear displacement of the tool and the feed of the tool.

Conventionally, it has been common practice to mechanically connect a tool and a workpiece with a transmission gear or the like, and to rotate the workpiece in synchronization with the rotation or linear displacement and feed of the tool using the transmission gear or the like.

This invention is a workpiece rotation control device that electrically controls the rotation of the workpiece in this type of generating gear cutting machine and can synchronize the rotation or linear displacement and feed of the tool with high precision. It provides:

This invention enables a rotating tool such as a hob or a rack-shaped linear displacement tool to be sent parallel to the axis of the workpiece, while at the same time being rotated or linearly displaced, and in synchronization with this, the workpiece is rotated to perform generating gear cutting. In a generating gear cutting machine that performs
A rotation amount or linear displacement detection pulse generator that generates the detection pulse; a feed amount detection pulse generator that detects the feed amount of the tool and generates the detection pulse; and a feed amount detection pulse generator that is connected to each of the pulse generators. , two synchronous circuits that output workpiece synchronous rotation pulses with a preset relationship to the detection pulses of each of the pulse generators; and synchronous rotation pulses of each of the synchronous circuits connected to each of the synchronous circuits. and a pulse synthesizer that outputs the synthesized pulse, and the rotation of the workpiece is synchronized with the rotation or linear displacement and feed of the tool by the synthesized pulse of the pulse synthesizer. This is a characteristic feature.

Further, according to the present invention, a microcomputer device is connected to each pulse generator and a pulse synthesizer, and the microcomputer device detects the average rotation of the tool at the start of machining based on the detection pulse of the rotation amount or linear displacement detection pulse generator. Measure the number or average linear displacement speed and the average rotational speed or average linear displacement speed of the current tool. Then, a correction amount for the synchronization deviation caused by fluctuations in the average rotation speed or average linear displacement speed of the tool is determined, and this is converted into a correction rotation pulse. Furthermore, the microcomputer device measures the tool feed rate at the start of machining and the current tool feed rate from the detection pulses of the feed rate detection pulse generator, and compensates for synchronization deviations caused by fluctuations in tool speed. The amount is determined and converted into a corrected rotation pulse. Then, each correction rotation pulse is output. Furthermore, the microcomputer device measures the time it takes for the tooth of the tool to move one bit from the detection pulse of the rotation amount or linear displacement detection pulse generator, calculates the difference between that time and a time constant, and calculates the delay of the magnitude of the difference. Outputs a time signal. Then, the pulse synthesizer synthesizes the synchronous rotation pulse of each synchronous circuit and the corrected rotation pulse of the microcomputer device, and the pulse synthesizer combines the synthesized pulse for a time corresponding to the magnitude of the delay time signal of the microcomputer device. Delay and output.

Embodiments of the present invention will be described below with reference to the drawings.

Here, a hobbing machine using a hob as a rotating tool will be explained. In FIG. 1, the tool or hob is rotated about its axis by suitable drive means and is fed parallel to the axis of the workpiece by a feed screw. A pair of pulse generators 1 and 2
are attached to the rotating shaft of the hob and the rotating shaft of the feed screw, respectively. The pulse generator 1 detects the rotation of the hob and generates a number of pulses _P1 as detection pulses according to the amount of rotation of the hob. The pulse generator 2 indirectly detects the feed of the hob through the rotation of the feed screw, and generates a number of pulses P ₂ as detection pulses corresponding to the amount of feed of the hob.

Each pulse generator 1, 2 is connected to a synchronization circuit 3, 4. Each synchronous circuit 3, 4 has an adder 5 and a divider 6, and gates 7, 8 are opened by pulses from the pulse generators 1, 2. When gates 7 and 8 are opened, addition and division are performed by adder 5 and divider 6, and pulses of the number of integer calculation values are
P ₃ and P ₄ are generated as workpiece synchronous rotation pulses. The remainder of the division is returned to gate 7. Adder 5 adds a constant to the numerical value returned to gate 7, and divider 6 divides this by a preset numerical value. The value of the divider 6 can be arbitrarily selected. Details of this addition and division will be described later.

Each synchronous circuit 3, 4 has a direction changeover switch 9,
It is connected to a pulse synthesizer 12 via 10 and 11. As will be described later, the direction changeover switch 9 is operated according to the twisting direction of the hob, and the direction changeover switch 11 is operated according to the twisting direction of the helical gear to be machined. The direction changeover switch 10 is connected to a pulse generator 2, which detects not only the feed of the hob but also the feed direction and generates a feed direction detection pulse _P5 . The direction changeover switch 10 is automatically controlled by this feed direction detection pulse _P5 .

Furthermore, a microcomputer device 13 is connected to each pulse generator 1, 2 and to the pulse synthesizer 12. The microcomputer device 13 receives the detection pulses from each pulse generator 1, 2, counts them, and can measure the time interval between the pulses. Therefore, as described later, the average rotational speed of the hob at the start of machining and the average rotational speed of the current hob are measured from the detection pulse P ₁ of the rotation amount detection pulse generator 1, and the fluctuation in the average rotational speed of the hob is measured. The amount of correction for the synchronization shift caused by is calculated, and this can be converted into a corrected rotation pulse _P7 . Furthermore, the hob feed rate at the start of machining and the current hob feed rate are measured from the detection pulse P2 of the feed rate detection pulse generator ₂ , and the amount of correction for synchronization deviation caused by fluctuations in the hob feed rate is determined. , this can be converted into a corrected rotation pulse _P6 . and,
Each correction rotation pulse P ₆ and P ₇ can be output. Furthermore, the time required for the hob teeth to move one pitch from the detection pulse P ₁ of the rotation amount detection pulse generator 1 is measured, the difference between that time and the time constant is determined, and the delay time signal P ₈ of the magnitude of the difference is obtained. It can be output.
In this embodiment, the microcomputer 13 has three
The arithmetic circuit 14 is connected to the feed amount detection pulse generator 2 and the pulse synthesizer 12, and the arithmetic circuits 15 and 16 are connected to the rotation amount detection pulse generator 1 and the pulse synthesizer 12. It is connected to the.

The pulse synthesizer 12 synthesizes the synchronous rotation pulses of the respective synchronous circuits 3 and 4 and the corrected rotation pulses P ₆ and P ₇ of the microcomputer 13, and converts the synthesized pulse P ₉ into a delay time signal P ₈ of the microcomputer 13.
The output can be delayed by a time corresponding to the size of . As shown in FIG. 4, in this embodiment, a delay circuit 20 is incorporated into the synchronization circuit 12,
This delay circuit 20 outputs a composite pulse _P9 . Then, the preset value of the delay circuit 20 is changed by the delay time signal _P8 of the microcomputer device 13, and this delay circuit 20 outputs the synthesized pulse _P9.
The delay time signal of the microcomputer device 13
Delay by a time corresponding to the size of P ₈ and output.

The pulse synthesizer 12 is a servo motor drive device 17
The drive device 17 is connected to the servo motor 1 by the synthesized pulse P ₉ from the pulse synthesizer 12.
8 to rotate the rotating shaft of the workpiece via a worm gear 19.

In the workpiece rotation control device configured as described above, the synchronous circuit 3 adds the detection pulse _P1 from the pulse generator 1 that detects the rotation of the hob.
A pulse P ₃ is generated to synchronize the rotation of the workpiece with the rotation of the hob. The synchronous rotation pulse P ₃ is transmitted from the pulse synthesizer 12 as a composite pulse P ₉ to the servo motor drive 17, thereby causing the workpiece to rotate in synchronization with the hob of the tool.

Addition and division by the synchronous circuit 3 are performed as follows. The constant added by the adder 5 is given the number of synchronous rotation pulses _P3 from the synchronous circuit 3 required to rotate the workpiece once. This number of pulses is Pwp/rev, and the number of detection pulses _P1 generated from pulse generator 1 during one rotation of the hob is
Ptp/rev, and the number of teeth of the gear to be machined is Z, then the required number of synchronous rotation pulses P _{3 that need to be generated from the synchronous circuit 3 for one detection pulse P 1 from} the pulse generator 1 is as follows: It is determined by the formula.

Necessary number of pulses=(remainder value returned to gate 7+Pw)/PtZ Therefore, PtZ may be given as the value of divider 6. The values of Pt and Pw are constants determined by the gear cutter. Number PtZ given by divider 6
is the product of constant Pt and variable Z, and is determined and set according to the number of teeth Z of the gear to be machined.

When machining the teeth of a helical gear on a workpiece, the rotation of the workpiece is controlled in relation not only to the rotation of the hob but also to its feed. It is well known that if the amount of rotation of the workpiece is increased or decreased in a fixed relationship in accordance with the feed of the hob, it is possible to machine a helical gear with a corresponding helix angle. Each synchronous circuit 3, 4 receives a detection pulse P ₁ from each pulse generator 1, 2 which detects the rotation and feed of the hob.
Pulse P ₃ for synchronizing the rotation of the workpiece with the rotation of the hob by adding and dividing by P ₂ , respectively.
Generates pulse _P4 to synchronize with hob feed. Each synchronous rotation pulse P ₃ , P ₄ is generated by a pulse synthesizer 12
and is transmitted to the servo motor drive device 17 as a composite pulse _P9 . By this,
The workpiece rotates in synchronization with both the rotation and feed of the hob, and the teeth of the helical gear are machined.

Addition and division by the synchronous circuit 4 are performed as follows. As in the case of the synchronous circuit 3, the adder 5 is given the number of pulses Pwp/rev required to rotate the workpiece once as a constant. If the number of pulses of the detection pulse P ₂ from the pulse generator 2 per unit feed amount of the hob is Pt'p/rev, and the lead of the helical gear to be machined is L, then the detection pulse P ₂ from the pulse generator 2 is The required number of synchronous rotation pulses P4 that must be generated from the synchronous circuit ₄ for one pulse is determined by the following equation.

Required number of pulses = (Remainder value returned to gate 7 + Pw) / Pt'L Therefore, the number given to the divider 6 is the product of the lead L of the helical gear to be machined and the constant Pt'Pt'L All you have to do is give.

In the case of a spur gear, the lead L can be considered to be infinite, so that the synchronous rotation pulse P ₄ from the synchronous circuit 4 is not generated.

The direction in which the workpiece is rotated needs to be changed depending on the rotation direction and specifications of the hob, such as the direction in which the hob is twisted. This is achieved by operating the direction changeover switch 9 depending on the rotational direction and specifications of the hob. When machining the teeth of a helical gear, it is also necessary to change the rotation direction of the workpiece depending on the twist direction of the helical gear to be machined. this is,
This is achieved by operating the direction changeover switch 11. In addition, when the hob is fed in both forward and reverse directions and gears are cut in each reciprocating stroke, the direction changeover switch 10 is automatically controlled by the feed direction detection pulse _P5 from the pulse generator 2, and the The rotation direction of the object is automatically changed according to the hob feeding direction.

By the way, in a hobbing machine, when a workpiece is cut by a hob and the teeth of a gear are machined, resistance to hob rotation and feeding changes depending on the amount of cutting. For this reason, fluctuations in the average rotational speed and feed speed of the hob are unavoidable. on the other hand,
In the case of a control device that controls the servo motor 18 based on the detection pulses P 1 and P ₂ of the rotation speed detection pulse generator 1 and the feed amount detection pulse generator ₂ , a control delay occurs for the workpiece, and a time delay occurs. It is well known that this occurs. Therefore, the detection pulses P ₁ , P ₂
After the occurrence of , the workpiece responds to it with a certain time delay or time constant. Therefore, there is a problem in that the hob and the workpiece are out of synchronization due to fluctuations in the average rotational speed of the hob and fluctuations in the feed speed of the hob. Arithmetic circuits 14 and 15 of the microcomputer device 13 are for correcting this synchronization deviation.

FIG. 2 shows the relationship between the variation in the average rotational speed of the hob and the tooth trace of the gear to be machined. The hob T is fed parallel to the axis of the workpiece W in the direction indicated by arrow A. As a result, teeth with a face width h are machined on the workpiece W. However, the cutting amount of hob T
increases and decreases depending on the feeding distance, and the resistance to rotation of the hob T changes. For this reason, the average rotational speed _N1 of the hob T at the start of machining changes, and this decreases to the average rotational speed _N2 . Then, before the machining is completed, the average rotational speed increases again to N ₁ . This variation in the average rotational speed of the hob is transmitted to the workpiece W with a time delay of a time constant, causing a synchronization difference.
Therefore, when the workpiece W is rotated as it is, the tooth trace A of the gear is deformed by a certain amount _δ1 .

The correction amount δ ₁ for the synchronization deviation caused by fluctuations in the hob rotation speed is determined by the hob rotation speed N ₁ at the start of machining and the current hob rotation speed Nn.
The correction amount _δ1 is determined. The calculation device 15 is
From the detection pulse P ₁ of the rotation amount detection pulse generator 1, measure the average rotation speed N ₁ of the hob at the start of machining and the current rotation speed Nn of the hob, and calculate the correction amount δ ₁ for the synchronization deviation using the following formula. demand.

δ ₁ = N ₁ - N ₂ /60xπxmxgxT δ ₁ ... Correction amount (mm) N ₁ ... Hob rotation speed at the start of machining (rpm) Nn ... Current hob rotation speed (rpm) m ... Module g... . . . Hob thread number T . . . Time constant (sec) Furthermore, the arithmetic circuit 15 converts this correction amount δ ₁ into a correction rotation pulse P ₇ and outputs this correction rotation pulse P ₇ .

In addition, regarding the correction amount δ ₂ for the synchronization deviation caused by fluctuations in the hob feed speed, the hob feed speed F ₁ at the start of machining and the current hob feed speed Fn
The correction amount _δ2 is determined by . The arithmetic circuit 14 detects the detection pulse of the feed amount detection pulse generator 2.
From _P2 , the hob feed rate _F1 at the start of machining and the current hob feed rate Fn are measured, and the correction amount _δ2 for the synchronization deviation is determined by the following equation.

δ ₂ =F ₁ -Fn/60xπxmxZx1/LxT δ ₂ ...Compensation amount (mm) F ₁ ...Feed rate at the start of machining (mm/min) Fn...Current feed rate (mm/min) Z... Number of teeth L: Gear lead (mm) Furthermore, the arithmetic circuit 14 converts this correction amount δ ₂ into a correction rotation pulse P ₆ and outputs this correction pulse P ₆ . Then, the pulse synthesizer 12 combines the synchronous rotation pulses of the respective synchronous circuits 3 and 4 with the respective arithmetic circuits 14 and 15.
The corrected rotation pulses P ₆ and P ₇ are synthesized.

In addition, during one rotation of the hob, that is, the teeth
During the pitch movement, instantaneous speed fluctuations of the hob occur,
This needs to be addressed. Figure 3 A is hob 1
Shows instantaneous speed fluctuations during rotation. Then, as shown in Fig. 3B, this instantaneous speed fluctuation is transmitted to the workpiece with a time delay of time constant ₃
occurs.

Now, assuming that the speed fluctuation rate in FIG. 3A is F%, the tooth profile error _δ3 is expressed by the following equation.

δ ₃ = KxF/100xπxmxg K...Coefficient In this equation, the coefficient K is determined by the ratio of the time constant X and the time C for one rotation of the hob, and its maximum value is determined when the ratio is 1/ 2, K=2.

The arithmetic circuit 16 is for dealing with the synchronization deviation caused by this instantaneous speed fluctuation. Third
As shown in FIG. 3C, the arithmetic circuit 16 measures the time C required for the hob to make one rotation, that is, the time C required for the teeth to move one pitch, from the detection pulse P1 of the rotation amount detection pulse generator ₁ . Further, the arithmetic circuit 16 calculates the difference between the time C and the time constant X, and outputs a delay time signal _P8 corresponding to the magnitude of the difference. The magnitude of the delay time signal _P8 , ie, the delay time U, is as follows.

U=C−X And this delay time signal _P8 is the pulse synthesizer 12
The preset value of the delay circuit 20 is changed by the delay time signal _P8 . The delay circuit 20 delays the composite pulse P ₉ by a time corresponding to the magnitude of the delay time signal P ₈ of the arithmetic circuit 16, that is, by a delay time U, and outputs the delayed signal.

Therefore, the command to control the servo motor is delayed, and then, with a further delay of time constant X, the rotational fluctuations of the hob are transmitted to the workpiece by the servo motor. The phase of the instantaneous speed fluctuation of the hob repeats a similar pattern with one rotation of the hob as one cycle C. As shown in the figure, the instantaneous speed fluctuation of the hob is transmitted to the workpiece with a delay of one cycle C due to the delay of the servo motor control command and the time constant X, and as a result, the instantaneous speed fluctuation of the hob rotates with a phase similar to that of . In this way, synchronization deviations caused by instantaneous speed fluctuations during one revolution of the hob are corrected, and gear teeth are machined on the workpiece with high precision.

As explained above, the present invention is capable of electrically controlling the rotation of the workpiece in a generating gear cutting machine, and synchronizing the rotation or linear displacement of the tool with the feed with high accuracy. It is capable of machining precision gears.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the relationship between the variation in the average rotational speed of the tool and the tooth trace, and Fig. 3A shows the variation in the instantaneous rotational speed of the tool. Figure 3(b) is a chart showing the phase difference between the rotational phase of the tool and the rotation of the workpiece, and Figure 3(c) shows the phase shift of Figure 3(b) by the arithmetic circuit of the microcomputer device in Figure 1. Figure 3D is an explanatory diagram showing the tooth profile error caused by instantaneous speed fluctuations of the tool, and Figure 4 is an explanatory diagram showing the circuit configuration of the pulse synthesizer in Figure 1. be. 1, 2... Pulse generator, 3, 4... Synchronous circuit, 12... Pulse synthesizer, 13... Microcomputer device.

Claims (1)

[Claims] 1. At the same time as feeding a rotary tool such as a hob or a rack-shaped linear displacement tool parallel to the axis of the workpiece,
In a generating gear cutting machine that performs generating gear cutting by rotating or linearly displacing the tool and rotating the workpiece in synchronization with the rotation or linear displacement, detecting the amount of rotation or linear displacement of the tool,
A rotation amount or linear displacement detection pulse generator that generates the detection pulse; a feed amount detection pulse generator that detects the feed amount of the tool and generates the detection pulse; and a feed amount detection pulse generator that is connected to each of the pulse generators. , two synchronous circuits that output workpiece synchronous rotation pulses with a preset relationship to the detection pulses of each of the pulse generators; and synchronous rotation pulses of each of the synchronous circuits connected to each of the synchronous circuits. and a pulse synthesizer that outputs the synthesized pulse, and the rotation of the workpiece is synchronized with the rotation or linear displacement and feed of the tool by the synthesized pulse of the pulse synthesizer. Characteristic workpiece rotation control device. 2. At the same time as feeding a rotary tool such as a hob or a rack-type linear displacement tool parallel to the axis of the workpiece,
In a generating gear cutting machine that performs generating gear cutting by rotating or linearly displacing the tool and rotating the workpiece in synchronization with the rotation or linear displacement, detecting the amount of rotation or linear displacement of the tool,
A rotation amount or linear displacement detection pulse generator that generates the detection pulse; a feed amount detection pulse generator that detects the feed amount of the tool and generates the detection pulse; and a feed amount detection pulse generator that is connected to each of the pulse generators. , two synchronous circuits that output workpiece synchronous rotation pulses with a preset relationship to the detected pulses of each of the pulse generators; The average rotational speed or average linear displacement speed of the tool at the start of machining and the current average rotational speed or average linear displacement speed of the tool are measured from the detection pulse of the detection pulse generator, and the average rotational speed or average linear displacement speed of the tool is determined. The amount of correction for the synchronization shift caused by the fluctuation of is measured, a correction amount for the synchronization deviation caused by fluctuations in the feed speed of the tool is determined, this is converted into a correction rotation pulse, each of the correction rotation pulses is output, and the rotation amount or linear displacement amount is detected. A microcomputer device that measures the time it takes for the tooth of the tool to move one pitch from the detection pulse of the pulse generator, finds the difference between that time and a time constant, and outputs a delay time signal of the magnitude of the difference; circuit and the microcomputer device, the synchronous rotation pulse of each of the synchronous circuits and the correction rotation pulse of the microcomputer device are combined, and the synthesized pulse is connected to the microcomputer device for a time corresponding to the magnitude of the delay time signal of the microcomputer device. and a pulse synthesizer that outputs a pulse synthesizer, the rotation of the workpiece being synchronized with the rotation or linear displacement and feed of the tool by the synthesized pulse of the pulse synthesizer. Workpiece rotation control device.