JPS597519A - Cutting method of gear - Google Patents

Abstract

PURPOSE:To enable to cut tapered gears by utilizing a general hobbing machine with its vertical or horizontal column. CONSTITUTION:A stepped tooth surface having an inclination as a whole or approximately tapered tooth surface is formed by gear cutting by generating process with a gear cutter 11, which is stepwise shifted relative to a gear blank W during cutting. The stepwise relative shift of the gear cutter 11 toward the blank W is performed by the increase or decrease of depth of cut while the cutter is fed parallel to the axis of the blank. Consequently, the gear, the tooth surface of which is tapered, can be cut with a general hobbing machine with its vertical or horizontal column.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gear cutting method for tapering the tooth surface of a gear using a hobbing machine.

Figures 1(a) and 1(b) show gears with tapers on the tooth surfaces. This gear 1 has a tooth surface 1a tapered in the direction of the tooth trace. Such a tapered gear 1 has the effect of preventing gear handling during driving when used, for example, as a gear of an automobile transmission. In the figure, 1b is the tooth bottom surface, and 1C is the tooth tip surface.

The above-mentioned tapered gear 1 has conventionally been gear-cut using a hobbing machine 2 shown in FIG. 2 in which a column 3 is inclined at a predetermined angle. That is, as shown in FIG.
After being cut by a predetermined distance relative to the gear material (hereinafter referred to as work) W attached to the gear material W, the material is sent obliquely upward along the inclined column 3. Therefore, the tooth surface 1a of the gear machined from the gear material W is tapered by diagonally feeding the bob 4 along the column 3 while gradually increasing the depth of cut. At this time, the amount of relative movement of the hob 4 in the cutting direction at the beginning of bobbing is determined by the amount of protrusion of the micrometer 7 that moves together with the workpiece W and operates the touch switch 6 . Further, the amount of relative movement of the hob 4 in the feed direction is changed by changing the age at which limit switches 9a and 9b are installed, which determine the upper and lower limits of the hob head 8. Note that the amount of cut herein refers to the relative movement of the hob 4 in the gear radial direction with respect to the workpiece W.

However, in gear cutting using the above-mentioned hobbing machine 2 in which the column 3 is inclined, the degree of taper depends on the inclination angle of the column 3, so there is a problem that the taper of the tooth surface cannot be freely changed. For this reason, in order to manufacture tapered gears with different tapers, dedicated bob machines must be prepared for each gear, which is uneconomical.

Furthermore, hobbing machines with inclined columns are expensive because they are special.

The present invention has been made by focusing on such conventional problems, and an object of the present invention is to provide a gear cutting method that can perform gear cutting of a tapered gear using a general hobbing machine with a vertical or horizontal column. With the goal.

In order to achieve this object, the present invention creates a step-like shape having an overall inclination by performing creative gear cutting with the gear cutting tool while moving the gear cutting tool relative to the gear material in a stepwise manner. A tooth surface, that is, an approximate taper tooth surface is formed. This stepped relative movement of the gear cutting tool with respect to the gear material can be achieved by increasing or decreasing the cutting distance during the feeding of the gear cutting tool in the gear axis direction. In other words, a gear with a tapered tooth surface can be manufactured using a general hobbing machine with a vertical or horizontal column. Moreover, according to the method of the present invention, by changing the stepped relative movement amount of the gear cutting tool, that is, by changing the cutting amount relative to the hob feed amount or the feed amount relative to the cutting amount, the desired value can be obtained. Tapers can be easily formed. Note that the step-like approximate taper tooth surface produced by the gear cutting method of the present invention is not a straight and smooth part, but it can be easily formed by grinding or shaving the south face after the main gear cutting. There is no problem because the step part is removed by finishing process such as machining and finished into a smooth tapered tooth surface.

The method of the present invention will be explained in detail below based on an embodiment shown in the drawings and FIGS. 4 to 9.

FIG. 4 shows a hobbing machine 10 for carrying out the method of the present invention. This hobbing machine 10 is a table moving type in which a column 13 to which a hob head 12 is attached is fixed and a table 14 to which the workpiece W is attached is moved forward in the direction of an arrow 25 to change the distance between the axes between the workpiece W and the hob 11. A mechanism for rotating the bob 11 and the workpiece W in a fixed relationship, a mechanism for sending the hob 11 relative to the workpiece W in the gear axis direction along the ram 13, and a mechanism for moving the workpiece W (daple 14) relative to the hob 11. It has a mechanism.

Between the table 14 and the bed 15, there is a movement path (drive amount) of the workpiece W/table 14 relative to the hob 11.
A forward positioning device 16 is provided for determining the forward direction positioning device 16 . This forward direction positioning device 16 consists of a micrometer 16a that moves together with the table 14 and a touch switch 16b that is fixed to the bed 15 side. When the switch 16b comes into contact with the switch 16b, the forward movement of the table 14, that is, the pushing-in is stopped, and then a command to raise the hob 11 is issued. In the case of the hobbing machine 1o of this embodiment, which is suitable for manufacturing a tapered gear with a relatively wide tooth width, it has a micrometer 16a of 3I] and a touch switch 16b, and each micrometer 16
By changing the protrusion amount of a, the workpiece W/table 1
It is provided to determine four different forward positions.

Of the touch switches 16b mentioned above, the third one at the lowest stage issues a backward command instead of a command to raise the hob 11 after a predetermined period of time has elapsed after stopping the movement of the table 14. Furthermore, the touch switch is a pushbutton switch with a built-in spring, which emits a signal output when the micrometer 16a comes into contact with it.

On the other hand, a vertical positioning device 18 for controlling the feeding of the hob 11 relative to the workpiece W in the direction of the gear axis is installed in the small saddle 17 portion. This vertical positioning device 18 consists of a limit switch 18a and a dog 18b that operates the limit switch 18a, and when the hob saddle 17 rises by a predetermined amount and one of the limit switches 18a comes into contact with the lower dog 18b. bob nadol 17
A command is issued to stop the upper limit of the table 14 and move the table 14 forward. bob 1
1 is determined by the mounting position of the dog 18b, and the subsequent rising stop position is determined by the mounting interval of the limit switch 18a. In addition, when the limit switch 18a comes into contact with the upper and lower dogs 18b, respectively,
After issuing a command to raise the hob saddle 17 and move the table 14 forward, a signal is provided to lightly lower the hob saddle 17 and the hob 11 for a predetermined period of time.

In the hobbing machine configured as described above, the mutual protrusion amount of the micrometers 16a is set in accordance with the increase in the cutting depth that occurs during feeding, and the mutual mounting interval of the kl'J mitt switches 18a is adjusted. If the setting is made in accordance with the intermediate hob raising stop interval, a gear with a tapered tooth surface 1a will be machined as follows.

First, the upper end limit switch 18a is set to the lower dog 1.
The hob 1 and the hob saddle 15 rise until they come into contact with the hob 8b. At this time, the mounting position of the upper end limit switch 18a is taken into consideration so that the hob 11 is located at the raised position l1 shown in FIG. 5(a). When the upper limit switch 18a is activated by the lower dog 18b,
The lifting of the hob 11 is stopped, and a command to move the table 14 and workpiece W forward is issued. This forward command causes the hob 11 to be driven relative to the workpiece W. When the first micrometer 16a at the upper end comes into contact with the touch switch 16b, the table forward movement stop command issued from the touch switch 16b causes the table to move forward.
stops. Note that the first micrometer 16a at this time
Between the protrusions, the hob 1 is in the forward position @1 shown in Fig. 5<a>.
After the table 14 stops moving forward, the hob 11 is moved to the above-mentioned tap switch 16.
In response to the ascending command issued along with the forward command from b, the machine starts cutting the gears while leaning upward. Thereafter, the hob 11 moves up until it comes into contact with the limit switch 18a, and then moves relatively to cut into the workpiece W until the micrometer 16a comes into contact with the touch switch. That is, hob 11
performs gear cutting while moving stepwise relative to the workpiece W. Therefore, the tooth bottom surface 1b of the workpiece W is
As shown in >, the curved surface forms a continuous staircase shape. Tooth surface 1
A similarly forms a step shape. These step-like approximate tapered tooth surfaces 1a and tooth bottom surfaces 1b have straight and smooth tapered surfaces and formed metal because the extra protruding portions where the surfaces intersect are scraped off in the subsequent grinding or shaving finishing process. Normally, shaving finish processing is performed on one side by 4
Approximately 0 μm is removed, but in the case of regular gear cutting, it is necessary to increase the amount by approximately 60 to 80 μm.

Further, FIGS. 7 and 8 show an example of a hobbing machine 10' for tapering a gear having a relatively narrow tooth width. This hobbing machine 10' has the same configuration as the hobbing machine 10 shown in FIG. 4, except that the number of set positions of the forward direction positioning device 16 and the vertical direction positioning device 111F1B is small. Incidentally, this hobbing machine 10' has a select switch 19, and by switching the switch 19, normal hob gear cutting can also be performed.

In the case of a gear with a relatively narrow face width, this is sufficient without increasing the number of times the depth of cut is increased during the feeding of the hob 11.

A constant angle taper can be placed on the tooth surface 1a. That is, Fig. 8 (
As shown in a), the hob 11 is advanced from the lowered position to the first forward position, then to the raised position, then advanced from this raised position to the second advanced position, and then after a certain period of time returns to the lowered position. will be returned to. Here, the above-mentioned fixed time refers to the time during which the workpiece W rotates one rotation or more. Hob 11
The tooth surface 1a and the tooth bottom surface 1b of the gear machined by stepwise relative feeding with respect to the workpiece W are flat parts 20a.
and a curved surface portion 20b, and the ridge angle portion 2 where these intersect
0d as an extra portion protruding from the desired tapered surface 20C, the tapered surface as a whole has a desired inclination. Therefore, the tooth surface 1a is finished by shaving the tooth surface corresponding to the above-mentioned ridge portion 20d, and is finished into a smooth tapered surface.

In addition, as shown in FIG. 9, the hob 11 is advanced to the forward position in FIG.
If the gear does not return to the forward position, a chamfered gear can be cut out as shown in FIG. 10(C).

As mentioned above, when cutting gears while moving the hob stepwise relative to the workpiece, it is possible to cut gears using a general hobbing machine with a vertical column, so the equipment is inexpensive, and The taper angle can be freely changed by appropriately changing the depth of cut ΔX and the minute feed shoe Δy.

[Brief explanation of the drawing]

FIG. 1 shows a gear with a taper, in which (a) is a partial perspective view, and (b) is a view taken in the direction of arrow A. FIG. 2 is a front view of a hobbing machine with an inclined column, and FIG. 3 is an explanatory diagram showing the movement of a hob in the same hobbing machine. FIG. 4 is a front view of a hobbing machine that carries out the gear cutting method of the present invention, and FIG.
It is an arrow view. FIG. 6 is a block diagram of the gear cutting method of the present invention. Fig. 7 is a front view showing another embodiment of a hobbing machine that implements the gear cutting method of the present invention, Fig. 8 is an explanatory diagram showing the movement of the hob in the hobbing machine, and Fig. 8 (b ) is a view of the teeth machined by the same hobbing machine in the direction of arrow C. 9th
Figure (a) is an explanatory diagram showing another example of the gear cutting method using the movement of the hob, Figure 9 (b) is a view of the teeth cut by the same gear cutting method in the direction of arrow D, and Figure 9 (0 ) is the same perspective view. 11... Hob, 16... Forward direction positioning device, 1
8... Vertical positioning device, W... Gear material (work). Patent applicant: Nissan Motor Co., Ltd. Figure 1 (') (b) Figure 2 Teaki'E? 13 Official Book (Method) October 1, 1980 Director-General of the Patent Office Kazuo Wakasugi 1, Indication of Matter A'i 1982 ("Patent Application No. 113,972 2, Title of Invention: Gear K2 [ Method 3: Relationship with the amendment filer case Patent applicant address: 2 Takaracho, Kanayō-ku, Yokohama-shi, Kanagawa Prefecture Name
(399) Nissan Motor Co., Ltd. Representative Shun Ishihara 4, Agent 5, Date of amendment order 1, Showa 5 [September 90 (shipment date: September 28, 1980) 6, Subject of amendment 7, FIG. 5(a) of page 11, lines 10 to 11 of the specification of amendments is a view of teeth cut out by the same hobbing machine in the direction of arrow B. 1-5 (a) is an explanatory view showing the movement of the hob in the same hobbing machine, and FIG. 5(b) is a view taken from arrow B of the teeth cut out in the same hobbing machine. ” he corrected.

Claims (1)

[Claims] A method for machining gears, characterized in that generating gear cutting is performed using the gear cutting tool while moving the gear cutting tool stepwise relative to the gear material.