JP3129923B2 - Gear hobbing machine finishing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION To finish a quenched and hardened gear after rough cutting, grinding is mainly performed. A gear grinding machine is expensive and requires a long processing time, and gear grinding is a costly processing method. In particular, grinding with a small pitch (module 1 or less) is difficult to form a grindstone and is not subject to machining. As these processing methods, finishing hob cutting is performed using a high-hardness gear hob such as a carbide hob or a cermet hob. The present invention relates to a gear finishing method for obtaining a high-precision gear at low cost.

[0002]

2. Description of the Related Art In the case of finishing hobbing a gear which has been roughly cut by a hobbing machine again, it is necessary to align a cutting edge of the hob with a tooth groove of the gear to be processed. As this method, the following method is generally known. 1) Master gear system The gear to be machined is processed while the gear to be machined and the master gear are always meshed, and by maintaining the phase between the hob and the master gear, the gear to be meshed with the new gear can be engaged. In the case where the gear to be processed and the master gear are not always engaged with each other, a method of storing the engagement position of the master gear with a numerical controller or the like and reproducing the position when the master gear and the gear to be processed are engaged is adopted. 2) Fixed position setting type When attaching the gear to be processed to the processing jig, attach the tooth groove based on the fixed fixed position and set it so that it engages with the hob in this state. The hob cannot shift an arbitrary distance, and the phase of the engagement shifts unless the shift is exactly one pitch. 3) Non-contact type There is a meshing method using an image processing system for processing an image from an image input device such as a CCD camera with a computer in a meshing state between a tool and a gear to be processed.

[0003]

In the case of the methods 1) and 2), it is necessary for an operator to manually and accurately determine the engagement position between the first hob and the gear to be processed. This has a significant effect on the engagement accuracy. 1) The method requires a master gear according to the gear to be machined, and it is difficult to accurately engage the master gear that is accurately machined with the gear to be machined for rough machining, and the meshing accuracy is low. Both 1) and 2) methods are difficult to automate.
3) The method requires expensive and precise equipment, and there are many problems in introducing a hobbing machine in a bad environment such as machining a small pitch or various helical gears or injecting a large amount of coolant. SUMMARY OF THE INVENTION An object of the present invention is to provide a hob that can automatically and precisely engage a hob and a work gear in finishing hobbing of a work gear from a very small pitch to a large pitch, and that can be used in an automated production line. To provide a board.

[0004]

Means for Solving the Problems] According to the present invention, a method of hobbing finishing the work gear rough gear cutting machined by numerical control hobbing, the hob cutting edge and the work gear
Before engaging the tooth groove, the sensor was placed in the center of creation between the hob and the workpiece gear, a pre-Symbol hob is rotating, the rake face of the cutting edge of the hob reaches the center of the creation At that time, it is detected by the sensor, the hob is stopped at that position, then the hob is axially shifted by an appropriate amount, and the sensor cuts the cutting edge of the hob.
Detecting the axial position, based on the detection signal, the axis of the cutting blade by a numerical control apparatus with respect to the center of the creation
Calculating the deviation of the directional position, converting the calculated value into a rotation angle value of the processed gear, using the converted value as a first rotation angle value, further rotating the processed gear by an appropriate angle, Rotation of the tooth groove of the processed gear by the sensor
Directional position is detected, and based on the detection signal, the numerical controller controls the tooth groove with respect to the creation center.
Calculate the displacement of the rotation direction position, convert the calculated value to the rotation angle value of the gear to be processed, use the converted value as a second rotation angle value, and convert the second rotation angle value to the first rotation angle. in addition to the value, only the total value shifting the angular position of said workpiece gear, which hobbing of a gear finishing method characterized by aligning the cutting blade and tooth spaces of the workpiece gear of the hob by the Provided.

Further, according to another configuration of the present invention, a rough
Hobbing of gears after gear cutting with a numerically controlled hobbing machine
In the method of finishing, the cutting edge of the hob and the tooth to be machined
Before engaging the teeth in the car, the sensor must be
It is placed at the center of creation between the gears to be machined and the hob is
Rotation from the rotation reference position, the rake face of the cutting teeth of the hob
When the sensor reaches the center of creation, the sensor
Is detected, and the hob is stopped at that position.
Next, the rotation angle value of the hob is calculated by a numerical controller.
Then, the hob is axially shifted by an appropriate amount,
Sensor detects the axial position of the cutting edge of the hob
Based on the detection signal, and
The axial position of the cutting blade with respect to the center of creation
And calculate the calculated value and the rotation angle value of the hob.
It is converted to the rotation angle value of the gear to be processed, and the converted value is
Used as one rotation angle value, and further,
Rotate the gear by an appropriate angle, and
The rotational direction position of the tooth groove is detected, and based on the detection signal
The center of the creation by the numerical controller.
The rotational position of the tooth groove is calculated, and the calculation is performed.
The value is converted into the rotation angle value of the processed gear, and the converted value
Is used as a second rotation angle value, and the second rotation angle value is
In addition to the first rotation angle value, the work
Shift the angular position of the gear, thereby cutting the hob
Align the tooth with the tooth groove of the processed gear,
After the finishing of the processed gear, each time the finishing of the other processed gear is performed, the rotational direction position of the tooth groove of the processed gear is detected by the sensor each time, and the numerical controller controls the position of the tooth with respect to the center of creation. calculating the deviation of the rotational position of the tooth space, and converted the calculated value to the rotation angle value of the processed gear used by the converted value and the second rotation angle value
While the hob is shifted axially in advance.
When this is done, the axial shift amount is converted to the rotation angle value of the processed gear, and the converted value is used as the shift amount rotation angle value.
The second rotation angle value and the shift amount rotation.
An angle value is added to the first rotation angle value, and the angular position of the gear to be processed is shifted by the total value, thereby aligning the cutting edge of the hob with the tooth groove of the gear to be processed.
Gear hobbing machine is provided.
It is .

[0006] Still further, according to another configuration of the invention, prior Symbol the axial thermal expansion of the hob is set based on actual machining data, the rotation angle value of the processed gear its axial thermal expansion amount in terms of, and the converted value and the thermal expansion rotation angle value, the
The second rotation angle value, the shift amount rotation angle value and the heat
The expansion rotation angle value is added to the first rotation angle value, and the angular position of the gear to be processed is shifted by the sum thereof , thereby aligning the cutting edge of the hob with the tooth groove of the gear to be processed.

In recent years, an ultra-high-speed, high-precision hobbing machine has been developed.
High processing conditions can be set so that the performance of carbide hob etc. can be fully exhibited. As a result, a machining method suitable for a mass production system in which finishing hobbing of a high-hardness gear can be performed in a short time has become possible. In order to perform stable processing under a long service life and high processing conditions of the finishing hob, it is desired that the gear to be processed has as little finishing processing margin as possible. For this reason, the gear groove position of the gear to be processed attached to the work support shaft and the cutting edge position of the hob attached to the hob shaft are automatically and accurately detected, and the optimum alignment is always performed with high precision. This is a condition for automatically performing stable processing. In the present invention, the left and right tooth flank positions of the cutting edge of the hob and the tooth groove of the gear to be processed are detected on a certain detection line by using a non-contact type displacement detection head, for example, an eddy current loss detector. The amount of deviation from the reference dimension on the detection line is calculated as the rotation angle of the work axis by the numerical controller, and the rotation angle is used as a correction angle from the origin of the work axis, and the rotation start position angle of the work axis with respect to the hob axis The teeth are adjusted by shifting.
During machining, the position of the cutting edge of the hob is instructed and moves, and the cutting edge is successively changed to a new cutting edge. Further, a correct cutting edge position including a displacement amount of the thermal displacement of the mechanical structure due to the heat generated by the operation of the machine in the axial direction of the hob shaft is detected. In the present invention, accurate tooth matching can always be performed by detecting the positions of the hob cutting blade and the gear teeth of the gear to be processed.

[0008]

The gears to be machined by the hobbing machine are most commonly spur gears and helical gears. Hob deepest cuts at the common tangent of the hob axis and the work gear axis (hereinafter referred to as workpiece axis), there are teeth creating areas on the left and right, and the hob axis
The common perpendicular to the workpiece axis is the center of creation. To align the cutting edge of the hob with the tooth groove of the gear to be processed, in the case of a spur gear, the position of the tooth groove at an arbitrary position in the tooth trace direction of the gear to be processed with respect to the cutting edge at the center of the hob creation. The tooth matching is established by the detection. However, in the case of the helical gear, the tooth alignment cannot be established unless a tooth groove is detected at the tooth trace position of the gear to be processed at the same position where the cutting edge at the center of the hob generation is detected. As described above, the non-contact type displacement detecting head is disposed at the center position of the rotation of the hob at the time of position detection, and moves to a position that does not hinder cutting after the detection is completed. When the positions of the left flank and the right flank of the cutting edge of the hob and the tooth groove of the gear to be machined at the center position of the hob rotation are at symmetrical distances, respectively, the tooth is in an optimum alignment position. In the present invention, the positions of the left tooth surface and the right tooth surface are detected, and a deviation amount of a detection value from an optimum tooth matching position is calculated as a rotation angle of a work axis by a numerical controller. After the angle is shifted, the hob cutting process starts with the synchronous rotation of the hob axis and the work axis. In the present invention, the gear to be machined is randomly mounted on the work shaft without any restriction on the tooth groove position at the mounting position, and further, the hob is firstly subjected to the tooth alignment position detection while being shifted by an arbitrary amount in the axial direction, Next, tooth matching is performed. After the tooth matching process is completed, the synchronous rotation of the hob shaft and the work shaft starts, and the processing conditions (cutting speed, cutting depth, hob feed speed, etc. The hobbing process is performed according to conditions set during the cutting process. A series of hobbing cycles of the tooth matching process and the hobbing process are configured as program commands of a numerical controller, and are automated.

[0009]

FIG. 1 is a schematic view of a hobbing machine embodying the present invention. 1 is a hob shaft for supporting a hob, and 3 is a rotary table for supporting a work, and is rotated about a work shaft 2. A gear generating motion is performed by synchronously controlling the hob shaft 1 and the work shaft 2 by a numerical controller, and the gear is cut by feeding the hob shaft in the axial direction Z of the work shaft. 2, 3 and 4 show an embodiment of the tooth matching device of the present invention. A hob shift table 5 constituting a hob shaft is supported in a hob head 4 rotatably supported on a swivel axis S so as to be able to shift in the Y direction. The tooth matching device 6 is installed on the hob head 4, and the non-contact type displacement detection sensor head 9 is attached to the head support 6a at the tip end. The center of the sensor head 9 is set at the turning center position of the hob head 4 at the time of detecting the hob cutting edge and the gear tooth groove to be processed. The rotation actuator 7 allows the tooth matching device to rotate except when the tooth matching detection work is performed, and allows the tooth matching device to escape to a position where the gear cutting is not hindered. The rotary actuator 8 can turn the head support 6a by 180 degrees so that the cutting edge of the hob H and the tooth groove of the gear W to be processed can be alternately detected. Further, the tooth matching device support 6b can be moved between the hob axis and the work axis by a drive source having a positioning function by servo drive or the like. FIG. 3 is FIG.
FIG. As shown in FIG. 4 , the tooth matching device 6 ′
May be installed on the support 11 . Next, the operation of the present apparatus will be described.

[0010] A hob H such as a carbide hob for machining a high-hardness gear is mounted on a hob shaft, and a gear cutting jig 1 is mounted on a rotary table 3.
0 and a gear W to be subjected to finish hobbing through a process such as heat treatment and hardening after coarse gear cutting. Next, the sensor head 9 located at the clearance position is moved to the hob head turning center position of the tooth registration detection position by the operation of the rotary actuator 7 of the tooth matching device 6. Next, it approaches the position required for measurement detection set in advance between the detection head and the hob cutting blade. In the operation of detecting the position of the hob cutting blade, the hob shift table 5 moves in the Y direction to a preset position to set the cutting start position of the hob H in the axial direction. Next, the hob shaft drive motor MB (hereinafter, shown in FIG. 9) rotates at a low speed and slowly rotates the hob (about 1
The hob moves to its rotation reference position (one rotation signal).
Signal detection position), the hob rotation signal detection switch
After detecting that, stop the hob at that position, reset the count value of the position coder to 0, and then
Was spun again at the rotational speed, it starts counting the number of pulses the position coder. And the hob's cutting blade
When the surface reaches the center of creation, a detection head (sensor)
The hob is stopped at that position, the pulse count is commanded to the numerical controller (NC) from the program sequencer (PMC), and the rotation reference position (one time)
The rotation angle Δθ of the hob from the rotation signal detection position) is obtained (FIG. 7). The reason for finding the rotation angle Δθ is hobbing finish
When processing, usually the hob once rotates at the rotation reference position (one rotation signal).
Signal detection position).
This is because the angle must be considered. The cutting edge of the hob is screw-shaped and the cutting edge surface is equally cut in the circumferential direction,
The cutting edge detected by the detection head is the cutting edge closest to the center of the generation, so that the cutting edge detected by the detection head is the cutting edge that is aligned with the blade groove of the gear to be processed .
5) . Then, by driving the Y axis motor MY from this position, e
8 is shifted in the axial direction by an appropriate amount,
The intersection of the detection line with both edges of the cutting edge is detected, and
The distances Y1 and Y2 to the intersection are measured. This allows
And it detects the axial Direction position of the cutting blade of the probe. Further
Then, the magnitudes of the distances Y1 and Y2 are converted into voltage values by the displacement meter controller and output to the comparator. The signal output at the set voltage value of the comparator is used as a skip signal of the numerical controller, the axis coordinate value at the time of signal output is read by the high-speed skip function of the numerical controller, and the deviation ΔY between the center of creation and the center of the cutting edge is determined. Calculate. Thus, data for setting the cutting edge position at the starting position of the hob H in the axial direction is obtained.
If the distance of ΔY is shifted in the Y direction, the position of the cutting edge can be obtained. However, in order to set the shift distance of the hob as effectively as possible, taking into account this, the initial set axial cutting start position is set as follows. It is better not to move. For this reason, a correction rotation corresponding to the Y-direction displacement of the hob shaft is given to the work axis (C axis). The rotation angle value Yθ of the C-axis is as follows: Yθ = {360 × (ΔY / Pa) + Δθ} / Z ΔY = displacement of the center of the cutting edge with respect to the center of creation at the axial cutting start position Pa: axial pitch of the hob Δθ: detected Angle of rotation Z: Number of gear teeth to be machined

Next, the operation of detecting the tooth groove position of the gear to be processed is performed by rotating the sensor head 9 shown in FIG. Approach the position required for measurement detection. Next, the rotary table 3 rotates left and right at low speed, detects the intersection of the one-side tooth surface on each specific circular line, and uses the same detection circuit as that used when detecting the hob cutting blade position to perform the numerical control with the numerical controller. The coordinate values (angles) θ1 and θ2 on the specific circle line are read (FIG. 6). this
To detect the rotational direction position of the tooth groove of the processed gear
Things. Since the read angle value is a rotation angle value of the C axis, if θ1> θ2 in FIG. 6, (θ1−θ
2) / 2 = Cθ, and Cθ is the corrected rotation angle corresponding to the amount of displacement on the circumference of the gear W to be processed. By shifting the sum of the Yθ value and the Cθ value from the initial position of the work axis (C axis), the initial tooth setting with a new hob is completed. Then
The hob cutting process is started by a synchronous rotation command of the hob shaft and the work shaft. Processing is successively continued with the same hob, but each time a new work gear is mounted, the tooth groove position is detected by the sensor head 9, and the corrected rotation angle Cθ is set to the work axis (C axis). For the hob, select either to shift in the axial direction each time machining is performed so that the cutting edge wear due to cutting does not become excessive, or to cut several at the same position and shift in the axial direction after cutting, and use a new cutting edge. Used. Hob shift can be accurately confirmed by the Y-axis servo motor in the amount of axial movement of the hob.
The value of θ is calculated, and the corrected rotation angle Yθ is set for each shift.

Further, in the hob cutting operation, cutting heat between the hob and the gear to be processed and heat generation of the transmission system cannot be avoided. The amount of heat displacement applied to the mechanical structure by the heat generated by these heat sources in a continuous operation becomes a large value in proportion to the elapse of the operation time, and also appears as the amount of displacement of the hob shaft in the axial direction. If the finish machining allowance of the gear to be machined is sufficiently large, it is possible to absorb the amount of thermal displacement of the hob shaft. Is desirable. For this reason,
In advance, data of the amount of displacement generated in the axial direction of the hob due to thermal displacement generated by various processing conditions is collected, and a program for correcting the patterned data value to the amount of shift at the time of the hob shift is prepared. Set the value. Yθ = [{360 × (ΔY / Pa)} / Z] ± δ (Δθ
= 0 except in the initial stage) ± δ: Corrected data value In order to improve the accuracy of tooth alignment, Yθ, which is measured only once, can be performed a plurality of times during processing (performed at regular intervals). There is a disadvantage that the machining cycle time increases. Although the reference is to detect the hob cutting blade and the work tooth groove, respectively, the hob cutting blade groove and the work tooth ridge may be detected.

[0013]

Gear finishing is performed for finishing hardened and hardened gears. However, gear finishing by hobbing using a high-hardness gear hob is in the process of being put into practical use. As a finishing method, there is an advantage that a processing accuracy close to gear grinding can be obtained in a low cost and a short processing time. In order to utilize this machining method on a production line, it is necessary to establish an automatic hobbing cycle including an accurate hobbing edge and a toothed groove of a gear to be machined in a short time. In the present invention, a non-contact type displacement meter is used as a position detector for the tooth alignment, and the cutting edge position of the hob and the tooth groove position of the gear to be processed are respectively detected, so that the alignment accuracy is high, Since the decrease in the accuracy of tooth alignment due to thermal displacement is eliminated, the left and right tooth surfaces can be correctly finished without any positional deviation even in the finishing allowance with a small number of gears to be processed. Since the entire process from detection to tooth matching is processed by the numerical controller according to the program command, the tooth matching process is extremely short, and a hobbing machine that can perform an automatic finishing hobbing cycle that can be used in a production line with a short tact time is possible. Was.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a hobbing machine embodying the present invention.

FIG. 2 is a schematic front view showing an embodiment of the tooth matching device applied to the present invention.

FIG. 3 is a schematic plan view of the embodiment apparatus shown in FIG. 2;

FIG. 4 shows a support 1 for the tooth matching device applied to the present invention.
FIG. 2 is a schematic plan view showing a case in which the device is installed in No. 1.

FIG. 5 is an explanatory diagram for explaining position detection of a hob cutting blade and position detection of a tooth groove of a gear to be processed in the tooth matching device applied to the present invention.

FIG. 6 is an explanatory diagram for describing a mode of detecting a correction rotation angle Cθ from coordinate values θ1 and θ2 on a specific circle line.

FIG. 7 is an explanatory diagram for describing an aspect of cutting edge detection in the hob rotation direction.

FIG. 8 is an explanatory diagram for describing a mode of hob cutting edge detection at a hob shift start position.

FIG. 9 is a block diagram showing a control system for the tooth matching device applied to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hob axis 2 Work axis 3 Rotary table 4 Hob head 5 Hob shift table 6, 6 'Tooth aligning device 9 Sensor head H Hob W Work gear S Rotating axis

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-249525 (JP, A) JP-A-7-148617 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23F 1/00-23/12

Claims (3)

(57) [Claims] 1. A method for hobbing and finishing a gear having been subjected to rough cutting with a numerically controlled hobbing machine .
Before engaging the cutting blade and the tooth groove of the gear to be processed, a sensor is disposed at the center of creation between the hob and the gear to be processed ,
The pre-Symbol hob is rotating, when the rake face of the cutting edge of the hob reaches the center of the creation, detect it by the sensor, to stop the hob at that position, then, an appropriate amount of the hob It is axially shifted, by the sensor detecting the axial position of the cutting edge of the hob, based on the detection signal, against the center of the created by a numerical control device
The deviation of the axial position of the cutting blades is calculated that, in terms of its calculated value to the rotation angle value of the processed gear, using the converted value as a first rotation angle value, further, the workpiece gear is suitable angle, detects the rotational position of the tooth space of the workpiece gear by said sensor, based on the detection signal, to-the center of the creation by the numerical control device
The deviation of the rotational position of the tooth space is calculated that, in terms of its calculated value to the rotation angle value of the processed gear, using the converted value as a second rotation angle value, the second rotation angle value In addition to the first rotation angle value, the angular position of the gear to be processed is shifted by the sum thereof, thereby aligning the cutting edge of the hob with the tooth groove of the gear to be processed. Gear finishing processing method. 2. Numerical control of the gear to be machined after coarse gear cutting
In the method of hobbing and finishing with a hob machine,
Before engaging the cutting edge with the tooth groove of the gear to be machined, the sensor
Is located at the center of creation between the hob and the gear to be machined,
Rotate the hob from its rotation reference position and
When the rake face of the incisor reaches the center of the creation,
Sensor detects it and stops the hob at that position.
And stop the hob by the numerical controller.
Then, the hob is shifted by an appropriate amount in the axial direction.
In the axial direction of the cutting edge of the hob
Detecting the position, and performing the numerical control based on the detection signal.
The axis of the cutting edge with respect to the center of creation by means of a device
Direction deviation, calculate the calculated value and the rotation of the hob.
Converting the rolling angle value to the rotating angle value of the processed gear,
Using the converted value as the first rotation angle value,
The processing gear is rotated by an appropriate angle, and the sensor
Detects the rotational direction position of the tooth groove of the gear to be processed and detects it
Based on the signal, the numerical control device
Calculates the deviation of the tooth groove's rotational position from the center
The calculated value is converted to the rotation angle value of the processed gear.
The converted value is used as the second rotation angle value,
The two rotation angle values are added to the first rotation angle value, and the total value is obtained.
Only by shifting the angular position of the work gear,
Align the cutting edge of the hob with the tooth groove of the processed gear
After finishing the gear to be processed, every time finishing the other gear to be processed, each time, the sensor detects the rotational direction position of the groove of the gear to be processed, and the numerical controller controls the numerical control. Of the tooth groove to the center of creation
Calculating the deviation of the rotational position, it converted the calculated value to the rotation angle value of the processed gear, as well as used by the converted value and the second rotation angle value, advance the hob
When the shift is performed in the axial direction, the shift amount in the axial direction is converted into the rotation angle value of the processed gear, and the converted value is converted into the shift amount.
Used as the rotation angle value, the second rotation angle value and
Adding the shift amount rotation angle value to the first rotation angle value, and shifting the angular position of the gear to be processed by the sum thereof, thereby aligning the cutting edge of the hob with the tooth groove of the gear to be processed. A hobbing machine gear finishing method. 3. An axial thermal expansion amount of the hob is set based on actual machining data, and the axial thermal expansion amount is converted into a rotation angle value of the gear to be processed. Values, the second rotation angle value, the shift amount rotation angle value, and the like.
And the thermal expansion rotation angle value added to the first rotation angle value.
The gear finishing method according to claim 2 , wherein the angular position of the gear to be processed is shifted by the total value, thereby aligning the cutting edge of the hob with the tooth groove of the gear to be processed. .