JP3643412B2 - Gear grinding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gear grinding apparatus that grinds a gear with a threaded grindstone, and particularly to a gear grinding apparatus that performs grinding with a combination in which the number of grindstones and the number of gear teeth are not prime.
[0002]
[Prior art]
Conventionally, in a gear grinding machine that grinds gears with a threaded grindstone, when machining gears with an odd number of teeth with two grindstones, all tooth surfaces are alternately processed with the first and second thread surfaces. Therefore, the pitch error between the first and second threads of the thread-shaped grindstone is transferred to the tooth surface, the pitch errors appear alternately, and the errors are averaged.
[0003]
Therefore, if the number of teeth that is relatively prime to the number of teeth is selected, the pitch error can be averaged, and the pitch accuracy can be improved.
[0004]
[Problems to be solved by the invention]
On the other hand, if a multi-threaded screw-type grindstone is used, the machining time can be shortened in proportion to the increase in the number of threads, but the number of teeth is set so that the number of teeth of the grindstone and the number of teeth of the gear are relatively prime. There is a problem that it is impossible to provide a large number of thread-like grindstones having different numbers of threads depending on the number because it requires a large amount of money.
[0005]
[Means for Solving the Problems]
The gear grinding apparatus of the present invention is made to solve the above-described problems. In the invention according to claim 1, the number of threads of the thread-like grindstone and the number of teeth of the gear are not the same. An approach direction moving means for relatively moving the screw-shaped grindstone and the gear toward each other while rotating the grindstone and the gear relative to each other, and the screw-shaped grindstone and the gear relative to the rotation axis direction of the gear. And a first discriminating unit that discriminates whether or not the gear has been ground by a predetermined depth of cut in a gear grinding apparatus that grinds the gear with the threaded grindstone based on a machining program. means and, by the gear by the first discriminating means is determined to have been predetermined depth of cut grinding, a predetermined number of teeth on the phase meshing not using the meshing phase of the said threaded grinding wheel gear Phase correction means for performing phase correction for shifting, and after the correction by the phase correction means is completed, relative movement of the screw-shaped grindstone and the gear by the axial direction movement means is performed without performing relative movement by the approach direction movement means. And a spark-out executing means for executing spark-out grinding.
[0006]
According to this, when the predetermined grinding process is performed on the gear by the threaded grindstone, and the first discriminating means determines that the gear is ground by the predetermined cut amount, the phase correcting means engages the threaded grindstone with the gear. The phase is shifted by a predetermined number of teeth to the meshing phase not using .
Next, the spark-out execution means performs the relative movement of the screw-shaped grindstone and the gear by the axial direction movement means without performing the relative movement by the approach direction movement means, and executes the spark-out grinding. Thereby, the pitch error in the gear is averaged.
[0007]
According to a second aspect of the present invention, in the gear grinding apparatus according to the first aspect, after completion of the spark-out grinding by the spark-out execution means, each tooth of the gear is at the time of grinding of the threaded grindstone. There is provided second discriminating means for discriminating whether or not spark-out grinding has been performed by the spark-out execution means for all the threads other than the used thread, and the phase when the second discriminating means discriminates it. It is characterized in that phase correction is performed by a correction means.
[0008]
According to this, since the tooth surface of each gear is always subjected to spark-out grinding with all the screw threads other than the screw thread used for grinding in the threaded grindstone, the pitch error in the gear is reliably averaged.
According to a third aspect of the present invention, in the gear grinding apparatus according to the first aspect, after the spark-out grinding by the spark-out execution means is completed, each tooth of the gear is at the time of grinding the threaded grinding wheel. Second discriminating means for discriminating whether or not the spark-out grinding by the spark-out executing means has been performed on a part of the threads other than the used thread is provided. It is characterized in that phase correction is performed by the phase correction means.
[0009]
According to this, it is possible to grind the gear with a part of the thread that is appropriately selected according to the demand for finishing accuracy, and to average the pitch error in the gear.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the overall configuration of a gear grinding machine, and an X-axis slide table 11 is slidably mounted in an X-axis direction (front-rear direction in the figure) on a bed 10 installed on the floor surface. The slide table 11 is driven to advance and retract in the X-axis direction via a ball screw (not shown) by an X-axis slide table driving motor 21 provided on the bed 10.
[0011]
A Z-axis slide table 12 is placed on the X-axis slide table 11 so as to be slidable in the Z-axis direction (left-right direction in the figure). The Z-axis slide table 12 is provided on the X-axis slide table 11. The Z-axis slide table drive motor 22 is driven to advance and retract in the Z-axis direction.
A headstock 13 and a tailstock 14 are installed on the Z-axis slide table 12 so as to face each other, and the spindle W and the tailstock 14 allow the workpiece W to be parallel to the moving direction of the Z-axis slide table 12. The workpiece W is supported so as to be rotatable around C, and is rotated by a spindle rotating motor 23 provided on the spindle stock 13.
[0012]
A column 15 is erected on the bed 10 in the forward direction of the X-axis slide table 11 (the front in the figure), and a swivel 16 is parallel to the moving direction of the X-axis slide table 11 on the front surface of the column 15. The swivel base 16 is swiveled around the axis A by a swivel base drive motor (not shown).
[0013]
A grinding wheel base 17 is provided on the swivel base 16 so as to be slidable in the radial direction (Y-axis direction) of the swivel base 16 perpendicular to the moving direction of the X-axis slide table 11. The grindstone base driving motor 27 is driven to advance and retract in the Y-axis direction via a ball screw (not shown).
A threaded grinding wheel 18 is supported on the grinding wheel base 17 so as to be rotatable about an axis B parallel to the moving direction of the grinding wheel base 17, and the threaded grinding wheel 18 is rotated by a grinding wheel rotating motor 28 provided on the grinding wheel base 17. It is designed to be driven.
[0014]
As shown in FIG. 2, the threaded grindstone 18 is configured as a two-threaded grindstone whose thread is composed of a first thread T1 and a second thread T2.
Further, as shown in FIGS. 2A and 2B, the work W uses a spur gear having 18 teeth on the circumference, and is adjacent to the work W in the circumferential direction. A pair of tooth surfaces facing each tooth Wa is assigned to tooth surface numbers N1 to N18.
[0015]
Here, the rotational axis B of the threaded grindstone 18 is inclined at a predetermined angle with respect to a plane perpendicular to the rotational axis C of the workpiece W such that the thread of the threaded grindstone 18 coincides with the tooth trace direction of the workpiece W. The angular position adjustment of the rotation axis B of the threaded grindstone 18 is performed by turning the swivel base 16 about the axis A by a swivel drive motor (not shown).
[0016]
Reference numeral 30 denotes a numerical controller, which is mainly composed of a central processing unit (CPU) 31, a memory 32, and an interface 33. In the memory 32, a workpiece W is machined to a finished diameter, and then sparked out. A machining program for controlling each device to perform a phase correction for rotation and performing a spark out again, each NC data, and the like are stored.
[0017]
The interface 33 is connected with an input / output device 34 having a keyboard for inputting data and a display device such as a CRT for displaying data, and the X-axis slide table driving motors 21 and Z. The motor drive circuits 41, 42, 43, 48 connected to the shaft slide table drive motor 22, the spindle rotation motor 23, and the grindstone rotation motor 28 are connected.
[0018]
These motor drive circuits 41, 42, 43, and 48 are driven by an X-axis slide table drive motor 21, a Z-axis slide table drive motor 22, and a spindle rotation motor 23 in response to a drive command signal output from the CPU 31 based on a machining program. The grindstone rotating motor 28 is driven.
The positions of the X-axis slide table 11 and the Z-axis slide table 12 respectively driven by the drive motors 21 and 22 are detected by the encoders 21a and 22a connected to the drive motors 21 and 22, respectively. The detection signals from the encoders 21 a and 22 a are fed back to the motor drive circuits 41 and 42 to perform position feedback control and are input to the numerical controller 30.
[0019]
Similarly, the rotation speeds and rotation phases of the gears (workpieces) W and the screw-like grindstone 18 that are respectively driven to rotate by the rotation motors 23 and 28 are detected by the encoders 23a and 28a. The detection signals from the encoders 23 a and 28 a are fed back to the motor drive circuits 43 and 48 to perform position feedback control and are input to the numerical controller 30.
[0020]
The grinding wheel base driving motor 27 and the turntable driving motor (not shown) are also controlled by the numerical controller 30 in the same manner.
Next, the operation of the present embodiment configured as described above will be described with reference to the flowchart shown in FIG.
The operator sets the workpiece W to be processed next as shown in FIG. 1 between the headstock 13 and the tailstock 14. Thereafter, in order to perform initial tooth alignment between the grindstone 18 and the workpiece W, as shown in FIG. 2, each angular phase at which the threads T1 and T2 of the screw-shaped grindstone 18 and the teeth Wa of the workpiece W are engaged is stored in the memory 32. Remember it in advance. The storage of each angle phase for the initial tooth alignment may be performed manually, or may be automatically performed using a sensor or the like.
[0021]
In this state, according to the machining program stored in the memory 32, first, the Z-axis slide table 12 is positioned so that the workpiece W is positioned at the machining original position at the left end in FIG. In addition to being positioned at a predetermined left traverse end position, the spindle rotating motor 23 and the grindstone rotating motor 28 are respectively driven by a synchronous rotation driving command to rotationally drive the threaded grindstone 18 and the workpiece W in synchronization. (Step 100). Here, since each of the rotational drive motors 23 and 28 for the thread-shaped grindstone 18 and the workpiece W has two threads, the tooth Wa of the workpiece W has two teeth during one rotation of the thread-shaped grindstone 18. Synchronous control is performed by outputting a rotation drive command to be rotated by an amount to each of the motor drive circuits 43 and 48.
[0022]
Next, based on the respective angular phases at which the threads T1 and T2 of the threaded grindstone 18 stored in the memory 32 and the teeth Wa of the workpiece W are meshed, a correction command corresponding to the amount of deviation is given to the motor 28 for rotating the grindstone. It outputs to the motor drive circuit 48, and tooth alignment (phase alignment) is performed (step 101).
Next, the X-axis slide table driving motor 21 is driven by the cutting advance command to advance the X-axis slide table 11 by a predetermined cutting amount in the X-axis direction (step 102).
[0023]
Next, the Z-axis slide table drive motor 22 is driven by a traverse command to traverse the Z-axis slide table 12 from a predetermined left traverse end position to a right traverse end position (step 103).
Next, it is determined in step 104 whether or not the workpiece W has been ground to the finish diameter. If not, the process returns to step 102 to advance the X-axis slide table 12 by a predetermined cutting amount, and then step In 103, the traverse is performed from the right traverse end position to the left traverse end position. Thus, until the workpiece W is ground to a predetermined finish diameter, a predetermined cutting amount is given for each traverse, and traversed a predetermined number of times between the left traverse end position and the right traverse end position.
[0024]
If it is determined in step 104 that the workpiece W has been processed to the finished diameter, the process proceeds to step 105.
In step 105, only the traverse movement of the Z-axis slide table 12 is executed without performing the cut in the X-axis direction by the spark-out command.
Then, in step 106, it is determined whether or not the spark-out is completed. If not, the process returns to step 105 to repeatedly perform the spark-out. Note that whether or not the spark-out has been completed is determined by the number of traverses.
[0025]
If it is determined in step 106 that the spark-out is completed, the process proceeds to step 107.
Here, at the time of grinding the workpiece (gear) W by the threaded grindstone 18 from step 102 to step 106 and at the time of sparking out, as shown in FIG. The engagement between the tooth T2 and the tooth Wa of the workpiece W is as follows: the first tooth T1 of the threaded grindstone 18 is the odd tooth surface N1, N3,..., N15, N17 of the workpiece W, and the even tooth surface N2, N4 is the second tooth T2. ,..., N16, and N18 are ground, the threaded grindstone 18 has two threads, and the number of teeth of the workpiece W is 18, that is, an even number of teeth N1. , N3,..., N15, N17 are always ground with the first thread T1, and even-numbered tooth surfaces N2, N4,.
[0026]
In FIG. 2A, the tooth surface marked with a circle is ground at the first thread T1, and the tooth surface marked with a ☆ is ground at the second thread T2.
In step 107, a phase correction signal for shifting the rotation phase of the workpiece W by one tooth in the rotation direction in response to the phase correction command is output to the motor drive circuit 43 of the spindle rotating motor 23. As a result, the meshing phase of the teeth Wa of the workpiece W and the threads T1 and T2 of the threaded grinding wheel 18 is shifted by one tooth of the workpiece W, and as shown in FIG. T1 corresponds to the even-numbered tooth surfaces N2, N4,..., N16, N18 of the workpiece W, and the second thread T2 corresponds to the odd-numbered tooth surfaces N1, N3,.
[0027]
Next, the process proceeds to step 108, and in the state where the rotation phase of the workpiece W is shifted by one tooth in the rotation direction by the spark-out command, similarly to step 105, the Z axis is not cut without cutting in the X axis direction. Only the traverse movement of the slide table 12 is executed, the first thread T1 of the threaded grindstone 18 is the even tooth surfaces N2, N4,..., N16, N18 of the workpiece W, and the second thread T2 is the odd tooth surfaces N1, N3,. .., Spark out each of N15 and N17.
[0028]
Note that after phase correction, the tooth surfaces marked with ● in FIG. 2B are spark-out ground at the first thread T1, and the tooth surfaces marked with ◯ * are ground at the second thread T2. ing.
Next, the process proceeds to step 109, and it is determined whether or not the spark-out is completed as in step 106. If not, the process returns to step 108 to execute the spark-out and traverse by spark-out grinding a predetermined number of times. If it is determined that the spark-out has been completed, the processing is terminated.
[0029]
As described above, when grinding a workpiece (gear) W having an even number of teeth (18 in the above example) using two threaded grindstones 18, at the end of grinding, By performing the spark-out grinding by shifting the meshing phase of the gear by one tooth, the pitch error of the ground gear caused by the pitch error between the first and second stripes is averaged, and the pitch accuracy can be improved. .
[0030]
In the above description, in order to shift the meshing phase of the tooth Wa of the workpiece W and the threads T1 and T2 of the threaded grinding wheel 18 by one tooth of the workpiece W, the phase correction signal by the phase correction command is sent to the motor of the spindle rotating motor 23. Although it is output to the drive circuit 43, it is output to the motor drive circuit 48 of the grindstone rotating motor 28 so that the pitch between adjacent threads of the threaded grindstone is shifted in the grindstone rotation axis direction (Y-axis direction). May be. In this case, a phase correction signal for shifting the rotational phase of the threaded grindstone 18 by 1/2 rotation may be output to the motor drive circuit 48, whereby the teeth Wa of the workpiece W and the peaks T1 and T2 of the threaded grindstone 18 are engaged. The phase is shifted by one peak in the grinding wheel rotation axis direction (Y-axis direction), and similarly, the pitch error of the ground gear caused by the pitch error between the first and second stripes can be averaged.
[0031]
Next, the operation of another embodiment of the present invention in the case where the number of threads of the threaded grindstone is 3 or more will be described with reference to the flowchart shown in FIG. In addition, the number of threads n (n ≧ 3) of the threaded grindstone and the number of teeth m of the gear (workpiece) are similarly non-prime combinations.
First, the spindle rotating motor 23 and the grindstone rotating motor 28 are respectively driven by a synchronous rotation driving command to rotate the screw-shaped grindstone 18 and the work W synchronously (step 200). Here, the rotation drive command is the rotation of n teeth of the tooth Wa of the workpiece W with respect to one rotation of the n-thread threaded grindstone 18.
[0032]
Next, based on each angular phase at which the threaded grindstone 18 and the workpiece W mesh with each other, a correction command corresponding to the amount of deviation is output and the teeth are aligned (step 201).
Next, in step 202 to step 204, a predetermined grinding process is performed on the workpiece W.
If the workpiece W has been machined to the finished diameter, the process proceeds to step 205 to execute spark out.
[0033]
If the traverse by the spark-out is performed a predetermined number of times and it is determined in step 206 that the spark-out has been completed, the process proceeds to step 207.
In step 207, a phase correction command signal for shifting the rotation phase of the workpiece W in the rotation direction by a predetermined number of teeth in accordance with the phase correction command is output to the motor drive circuit 43 of the spindle rotating motor 23.
[0034]
Here, by shifting the rotation phase of the workpiece W by a predetermined number of teeth in the rotation direction, the workpiece W and the threaded grindstone 18 are engaged with each other at a meshing phase that is not used other than the meshing phase at the time of grinding.
In order to shift the pitch between adjacent threads in the n-thread threaded grinding wheel in the grinding wheel rotation axis direction (Y-axis direction), a phase correction signal for shifting the rotation direction by 1 / n rotation is output to the motor drive circuit. Is done.
[0035]
Next, in a state where the meshing phase is not used, spark-out is performed in steps 208 and 209.
When the spark-out is completed, the routine proceeds to step 210, where it is determined whether or not each tooth Wa of the gear W has been subjected to the spark-out grinding with all the threads of the threaded grinding wheel 18.
[0036]
If it is determined NO in step 210, the process returns to step 207, where phase correction is performed again according to a phase correction command that is a mesh phase that is not used, which is different from the previous one, and then spark out is performed in step 208. To be implemented.
Here, for example, when grinding is performed between three threaded grinding wheels and a gear having 3n (n is an integer) number of teeth, each gear tooth is sparked out by all three. In order to achieve this, it is necessary to perform a spark out by performing a phase correction command for shifting the rotational phase of the grindstone by 1/3 rotation and 2/3 rotation, but in this case, from which order the phase correction commands are issued But it ’s okay.
[0037]
That is, since each tooth of the gear is subjected to spark-out grinding with all the n strips, when there are a plurality of phase correction commands, the order may be random or may be shifted in order by one tooth. .
If it is determined in step 210 that each tooth Wa of the gear W has been sparked out by all the threads of the threaded grindstone 18, the processing is terminated.
[0038]
As described above, in the present embodiment, since each tooth of the gear is subjected to spark-out grinding with all the threads, even in the case of three or more thread-like grindstones, the pitch error of the gear is reduced. Averaging is ensured and pitch accuracy can be improved.
In the above description, each tooth of the gear is subjected to spark-out grinding with all the screw threads, but may be subjected to spark-out grinding with a predetermined thread instead of all the screw threads. In this case, in step 210 in the flowchart shown in FIG. 4, it may be determined whether or not each tooth Wa of the gear W has been subjected to spark-out grinding with a predetermined thread of the threaded grindstone 18.
[0039]
According to this, the gear can be ground with a predetermined thread appropriately selected according to the demand for finishing accuracy, and the pitch error of the gear can be averaged.
Further, in the above, after the workpiece (gear) W has been processed to the finished diameter, spark out is performed, and after the completion of the spark out, a correction command for shifting by a predetermined number of teeth is issued. It is possible to issue a correction command for shifting by a predetermined number of teeth by discriminating whether W has finished machining to the finished diameter and judging that machining has been finished to the finished diameter, that is, the gear grinding according to the present invention. After determining whether or not a predetermined cutting amount of grinding has been completed, the apparatus performs a spark-out by shifting the meshing phase of the threaded grinding wheel and the gear by a predetermined number of teeth to the meshing phase not using the gearing phase. Various modifications can be made without departing from the technical idea of averaging the pitch error.
[0040]
【The invention's effect】
According to the present invention, in the first aspect of the invention, when grinding is performed with a combination in which the number of threads of the thread-like grindstone and the number of teeth of the gear are not prime, after grinding a predetermined cutting amount on the gear Since the meshing phase of the threaded grinding wheel and the gear is shifted to the meshing phase not using the predetermined number of teeth and the spark-out grinding is performed, the pitch error of the ground gear caused by the pitch error in each line can be averaged. The pitch accuracy can be improved.
[0041]
In the invention according to claim 2, since it is determined whether or not all spark-out grinding has been completed by the second determining means, the tooth surface of each gear is always used when grinding a threaded grinding wheel. All the threads other than the above-mentioned thread are subjected to spark-out grinding, and the pitch error of the gear can be surely averaged, and the pitch accuracy can be further improved.
[0042]
In the invention according to claim 3, the second discriminating unit discriminates whether or not each tooth of the gear is ground by a part of the screw threads other than the screw thread used at the time of grinding the threaded grindstone. Therefore, the gear can be ground with a part of the threads that are appropriately selected according to the demand for finishing accuracy, and the pitch error of the gear can be averaged.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a gear grinding machine showing an embodiment of the present invention.
FIG. 2 is an operational state diagram showing meshing during grinding of a workpiece (gear) by a threaded grindstone.
FIG. 3 is a flowchart showing the operation of the embodiment of the present invention.
FIG. 4 is a flowchart showing the operation of another embodiment of the present invention.
[Explanation of symbols]
10 bed 11 X-axis slide table 12 Z-axis slide table 13 headstock 14 tailstock 17 grindstone table 18 grinding wheel 21 X-axis slide table drive motor 22 Z-axis slide table drive motor 23 spindle rotation motor 28 grinding wheel rotation Motor 30 Numerical control device T1 1st line T2 2nd line W Workpiece (gear)
Wa teeth

Claims (3)

An approach direction movement that relatively moves the threaded grinding wheel and the gear toward each other while rotating the threaded grinding wheel and the gear with a combination in which the number of threads of the threaded grinding wheel and the number of teeth of the gear are not prime. A gear grinding device for grinding the gear with the threaded grindstone based on a machining program, and an axial direction moving means for relatively moving the threaded grindstone and the gear in the rotational axis direction of the gear A first discriminating means for discriminating whether or not the gear has been ground by a predetermined depth of cut; and by determining that the gear has been ground by a predetermined depth of cut by the first discriminating means, a phase correction means for performing a phase correction of shifting the predetermined teeth number of the meshing phase not using the meshing phase of the gear, after the correction by the phase correction means is completed, the approaching direction move Performs relative movement of the threaded grinding wheel and the gear by the axial movement means without relative movement by means, gear grinding apparatus being characterized in that a spark-out executing means for executing the spark-out grinding. 2. The gear grinding apparatus according to claim 1, wherein after the spark-out grinding by the spark-out execution unit is completed, each tooth of the gear is a screw thread other than the one used at the time of grinding the threaded grindstone. Second determining means for determining whether or not spark-out grinding has been performed by the spark-out executing means is provided, and phase correction by the phase correcting means is performed when the second determining means determines NO. Gear grinding device characterized by the above. 2. The gear grinding apparatus according to claim 1, wherein after the spark-out grinding by the spark-out execution unit is completed, a part of the threads of the gear other than the thread used at the time of grinding of the threaded grindstone. A second discriminating means for discriminating whether or not the spark-out grinding has been performed by the spark-out executing means, and the phase correction by the phase correcting means is performed when it is judged by the second discriminating means to be negative. A gear grinding apparatus characterized by that.

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