JPS6039488B2 - Automatic tooth alignment method on numerically controlled hobbing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a numerically controlled hobbing machine that uses NC control to synchronize a hob cutter and a work table that are driven by separate rotation systems.

In a conventional hobbing machine, the hob cutter and work table are completely connected by a gear train, and the work table rotates synchronously according to the rotational speed or movement of the hob cutter, as shown in Figure 4 1, 2, and 3. ing.

Further, the other feed axes also move correctly depending on the speed ratio of the gear train according to the movement of the hob cutter. However, hobbing machines that do not have such a gear train, namely numerically controlled hobbing machines (NC
When using a hop cutter (also called a hop cutter), it is important to find out how to synchronize the hob cutter and worktable. There are several methods for controlling the hob cutter and worktable, but the method most commonly used in the already announced NC hobbing machines is to rotate the hob shaft with an electric motor and calculate its rotational speed using an NC control device. Then, a command is given to the table drive motor so that a gear having a predetermined number of teeth can be machined.

A hobbing machine incorporating such an NC control device makes it easy to process special gears such as crowning gears, taper gears, and two-step gears, and also allows for easy setup and short preparation time (non-cutting time). It has many advantages such as being short. However, on the other hand, functions that could naturally be performed with a hobbing machine with a fixed mechanical relationship are quite troublesome functions with an NC hobbing machine because an NC device is interposed between the hob cutter and the work table. Examples have arisen. For example, cutting twice (rough cutting and finishing cutting) or changing the cutting direction of the helical cut (climb cut and conventional cutting). To realize NC hobbing, a pulse corresponding to the rotational speed of the hob shown in Figure 1 is detected,
Based on this, the table driving electric motors may be driven in synchronization.

If desired, it is possible to consciously increase or decrease the rotational speed of the hob cutter during processing, and the table drive electric motor can fully follow suit after a certain period of time. However,
Since the current general NC devices are mainly based on soft servo, the control system has delay characteristics, and due to the delay characteristics of the control system, there is always a follow-up delay shown in FIG. 2 in the rotation of the table. For example, when the table speed changes from V to V2, the following speed can be reached after a certain time, but the amount of delay (druve) changes significantly. For this reason, it is not possible to properly index the teeth when cutting the teeth.
(See Figures a and b). Therefore, it is difficult to change the cutting conditions in the middle of cutting a workpiece that has started to be gear-cut using an NC hobbing machine. In other words, it is difficult to continuously perform rough cutting and finishing cutting at different cutting speeds. With conventional hobbing machines, the three items of cutting speed, feed rate, and feed direction can be easily changed during cutting, but with NC hobbing machines, the phase of the hob cutter and the work table at the time of tooth cutting (the positional relationship between the cutter and the workpiece) can be easily changed during cutting. ) have to be matched. The present invention has been made in view of the above circumstances, and is a numerically controlled hop that can correct the follow-up lag of the table drive system that occurs when changing the cutting speed (rotational speed of the hob) during cutting in an NC hobbing machine. The purpose is to provide an automatic tooth alignment method for discs.

The configuration of the present invention that achieves such an object is a numerically controlled hobbing machine that has a motor that drives a hob, a motor that drives a table, and a control system that controls the table rotation speed based on the rotation of the hob. When changing the rotation speed of the hob, the table drive system or The present invention is characterized in that by controlling the hob drive system, the position of the hob or the table is corrected by an amount corresponding to the amount of delay in the number of rotations of the table.

Embodiments of the present invention will be described below based on the drawings.

First, the NC control system will be explained with reference to FIG. 9, which is a block diagram thereof.

When a hob rotation speed command is input, the spindle motor rotates based on that command, and the hob rotational position is checked by an encoder.
The information from the encoder is input to the control device, and the information from the encoder is input to the smoothing circuit together with a pre-stored tooth number command value.

The information input to the smoothing circuit is input to the digital phase modulation circuit, and through the position control circuit and amplifier circuit, commands for the rotation speed and rotation phase that can properly process gears are output to the table drive motor. . The rotation by the table drive motor is fed back to the position control circuit and amplifier circuit by the tachogenerator and resolver, and the commanded rotation speed and rotation phase are compared with the actual rotation speed and rotation phase. In this control system, the drive motors for the hob and the table are provided independently, and the table rotation speed is controlled based on the rotation of the hob, so there is a follow-up delay between the hob and the table.

Assuming that the spindle motor and smoothing circuit are first-order delay systems, the amount of delay Δ in the table rotation speed relative to the hob can be expressed as in the following equation. △: KX studies x gX voice p + TS
) ...[1; Here, K: Constant of the NC control system, N: Hob main shaft rotation speed, (r.p.m.) Z: Number of gear teeth g: Number of hob ports, Kp: Position rube gain, (rad/ sec) Ts: smoothing time constant (msec).

In other words, this is the delay characteristic of the '11 Type 1 Kooshi-Teku Tonju TS sail line system.

The amount of delay Δ obtained from equation {1) is calculated by the computer library of the NC device, and the table shaft drive system that is the table drive system or the hob shift shaft drive system that is the hob drive system is controlled based on the delay amount Δ.

In other words, as shown in Fig. 10, which is a block diagram when the delay amount △ of the table rotation speed is output to the table shaft drive system, the delay amount △ is calculated after inputting the hob rotation speeds N, N2 before and after the change. △=KX dream XgX (far 10h) calculate the beam. The calculated delay amount Δ is input to the pulse distribution, and then input to the smoothing circuit together with the table axis movement command value. The table axis movement command information input to the smoothing circuit together with the information on the delay amount Δ is outputted as a drive command for the table drive motor in the same manner as in the above-mentioned NC control system. Therefore, even if the rotational speed of the hob changes, the table drive motor is controlled and driven so that there is no follow-up delay to the rotation of the hob, so the hob and workpiece gear are always in phase with each other in a normal state. It is. Next, the case where the above-mentioned method is applied to various gear machining will be explained.

When performing rough cutting (▽) and finishing cutting (▽▽) twice or more, the difference in cutting speed and feed direction (workpiece
refers to the axial direction of

(the same applies hereafter), a tracking delay (droop) occurs that is difficult to change. It is common knowledge that the cutting speed is different between rough cutting (▽) and finishing cutting (▽▽), but due to the speed change in this case, a considerable follow-up delay occurs in the table driving electric motor 1. Of these, the follow-up delay due to the difference in cutting speed is eliminated by hob shifting (W) or rotation of the work table 2, as shown in FIGS. 5 1, 2, 3 and 6. The hob shift (w〆,) is the movement of the hob cutter 3 in the direction of the hob, and its amount is calculated in advance based on the data shown in FIG. The hob shift (state finalization) is performed after the hob cutter 3 and the workpiece W are separated from each other after rough cutting (▽). For example, as shown in Fig. 5, 11, after rough cutting (▽) with climb cut (↑), hop shift (bezu), then finish cutting (▽▽) with conventional cut (↓), and return to the original position (◎). let Or as shown in Figure 5 2, conventional cut (↓)
After rough cutting, the hob cutter 3 and the workpiece W are separated, the hob is shifted (beveled), and then returned to the original finishing position (◎) with a climb cut (↑). Alternatively, after rough cutting (▽) with climb cut (↑), move hob cutter 3 to its original position (◎).
After returning it to , hop shift (zuzu), and finish cutting (▽▽) with climb cut (↑). In addition to eliminating the follow-up delay due to the hob shift (Luzo), the work table 2 is rotated ( ) to compensate for the follow-up delay as shown in FIG. For example, rotate it 30 times. In addition, the follow-up delay caused by continuously cutting after changing the feed direction will appear as a deviation in the feed direction. Eliminate.

At this time, the follow-up delay is doubled. As above 2
When performing rough cutting and finishing cutting by rotary cutting,
Since the follow-up delay of the work table drive motor 1 due to changes in cutting speed and feed direction is combined, it is necessary to perform the above-mentioned two correction methods simultaneously.

That is, this is performed by correcting the position of the hob cutter 3 in the feeding direction, and by shifting the hob (small) or rotating the workpiece W for correction (2). Also, in the case of a helical gear, the follow-up delay caused by the two cuts of rough cutting (▽) and finishing cutting (▽▽) is caused by hob shift (small) as explained based on Fig. 5 1 to 3 and Fig. 6. Alternatively, the problem can be solved by corrective rotation of the work table 2. However, as shown in Figure 7, there is a shift in the position of the S point and F point on the table, so if you change the cutting direction in the second cut of the helical gear, there will be a follow-up delay, so the helical gear cannot be processed correctly. Similarly, a follow-up delay occurs when changing the feed rate. Therefore, as shown in Fig. 8, when changing the feed direction in the hemi-calgia, the delay in the feed direction caused by this can be effectively reduced by applying a corrective rotation to only the workpiece W from the reference point on the table 2 and starting. The follow-up delay is absorbed by changing the feed amount to the target workpiece W. In addition, when changing the feed speed, the position of the cutter is corrected in the feed direction by an amount corresponding to the delay amount obtained in Fig. 2 according to the speed ratio, until it cuts into the workpiece W. change the time to absorb the tracking delay. Alternatively, this can be done by applying corrective rotation to the work table 2. As described above, according to the present invention, the amount of delay in the table rotation speed that occurs when the rotation speed of the hob is changed is determined, and the hob position or table position is corrected based on this amount of delay. There is no dust that causes the hob and workpiece to be out of phase even when the speed is changed.

As a result, cutting conditions can be easily changed during cutting.

[Brief explanation of the drawing]

Fig. 1 is a gear system diagram of an NC hobbing machine, Fig. 2 is a graph showing an example of experimental data showing follow-up delay of the table drive motor, Fig. 3a shows the meshing of the hob cutter and the workpiece,
FIG. 1b is an explanatory diagram showing the adverse effect of the follow-up delay of the table drive motor. FIGS. 4, 1, 2, and 3 are explanatory diagrams showing an example of double cutting performed by a conventional hobbing machine equipped with a gear train indexing mechanism. 5 and subsequent figures show the manner in which the follow-up delay is corrected by the method of the present invention. Figure 6 is an explanatory diagram showing an example of eliminating the follow-up delay, which is difficult to change the cutting speed, by corrective rotation of the work table, and Figure 7 is a front view a and a top view b showing deviations in the rotation of the work table in the case of a helical gear. Fig. 8 is an explanatory drawing showing position correction in the feed direction and table position correction in two-cutting of edge calving machine, Fig. 9 is a block diagram showing the control system of the NC hobbing machine, and Fig. 10 is an explanatory drawing showing the table position correction. FIG. 3 is a block diagram of a control system when the table drive system is controlled based on the amount of rotation speed delay.
In the drawings, 1 is the drive motor for the work table, 2 is the work table, 3 is the hob cutter, W is the work, small is the hob shift, ↑ is the climb cut, `` is the conventional cut, ▽ is the rough cut, ▽ ▽ is the finish cut, ◎ is the original position. Figure 1 Figure 2 Figure 4 Figure 6 Figure 3 Figure 5 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] 1 When changing the rotation speed of the hob during machining on a numerically controlled hobbing machine that has a motor that drives the hob, a motor that drives the table, and a control system that controls the table rotation speed based on the rotation of the hob, the rotation of the hob number, number of hob mouths,
Calculate the amount of delay in the table rotation speed by adding the delay characteristics of the control system to the table rotation speed determined by the number of teeth on the workpiece.
A numerically controlled hobbing machine characterized in that the hob position or table position is corrected by an amount corresponding to the delay amount of the table rotation speed by controlling the table drive system or the hob drive system based on the delay amount. automatic tooth alignment method.