JPH0586304B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a helical gear rolling device.

[Conventional technology]

In general, gears are widely used in various rotating mechanisms for the purpose of changing rotational speed. For example, in automobiles, gears include spur gears and helical gears in transmissions, helical gears in drive shafts, etc. Are known. In the past, such gears were generally manufactured using gear cutting methods such as the generating gear cutting method and the molding gear cutting method, but recently gears by rolling have been manufactured due to the ease of manufacturing. The manufacturing method is attracting attention. Particularly today, as engine output tends to increase, gears used in automobile drive systems, such as helical gears in drive shafts, are required to have sufficient toughness.From this point of view, the rolling method, which also plastically works the workpiece, is promising. This is a manufacturing method for gears.

Here, the gear rolling method involves arranging a pair of rolling dies, each consisting of a tooth group and a finishing tooth group arranged in sequence, facing each other, and rolling the workpiece between the dies using a center. In this method, both dies are supported rotatably and moved relative to each other to form a desired gear shape on the outer peripheral surface of the workpiece.

By the way, when rolling a helical gear among gears, as shown in FIG. 5, when the die moves relative to each other, the die engages with the workpiece 20, and when the die moves relative to each other, the engaging portions 21a,
21b moves obliquely upward in the figure, the teeth of the die push the workpiece 20 apart, thereby rolling the helical gear. At this time, a force in the direction of the arrow A in the figure acts on the workpiece 20. If the axial component B of this force becomes larger than the center pushing force, the workpiece 20 will move toward the center, resulting in a problem that the tooth profile accuracy will deteriorate.

Therefore, in conventional helical gear rolling equipment, as shown in Japanese Patent Application Laid-Open No. 59-209452, when a workpiece is supported at both the center of the main spindle and the tailstock,
There is one in which the tailstock is clamped from above using a clamping member to reduce the axial displacement of the workpiece during rolling and improve the tooth profile accuracy.

[Problem that the invention seeks to solve]

However, in the device described in the above-mentioned conventional publication, in order to reduce the axial displacement of the workpiece during rolling, it is necessary to firmly clamp the workpiece with sufficient holding force, and in this case, the workpiece itself must also be fixed due to the clamping method. As a result, there was a risk of seizure occurring between the workpiece and the center.

In view of these problems, the present invention aims to provide a helical gear rolling device that can suppress the axial displacement of a workpiece during rolling without causing problems such as seizure.

As a method to suppress the axial displacement of the workpiece,
It is conceivable to set the pushing force of the workpiece to a sufficiently large value. However, in this method, the die is not fully engaged with the workpiece in the early stage of the engagement area of the die's biting teeth, and the axial component of the force acting on the workpiece is also small, so the problem is caused by a large pushing force. This time, the workpiece moves to the other center side, causing a misalignment in the engagement between the die and the workpiece, resulting in poor tooth profile accuracy.

[Means for solving problems]

Therefore, the present invention provides an apparatus for forming a helical gear on the outer peripheral surface of a workpiece by engaging a rolling die with a workpiece supported by both centers. The biting tooth engagement area where the height of the teeth gradually increases is larger than that when supporting the workpiece, and the finishing tooth engagement area is set to be smaller than the biting tooth engagement area. It is something.

[Effect]

In this invention, in the biting tooth engagement area of the die where the height of the teeth gradually increases, the pushing force of the center on the workpiece axial displacement side is set to be larger than when supporting the workpiece. is moved to the other center side by the pushing force of the center, and no misalignment occurs in the engagement between the die and the workpiece.
The die engages with the workpiece accurately and reliably, and the pressing force of the center is set smaller in the finishing tooth engagement area than in the biting tooth engagement area, so the force acting on the workpiece during rolling is reduced. The displacement of the workpiece due to the axial component of is suppressed.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 show a helical gear rolling device according to an embodiment of the present invention. In the figure, 1 is a U-shaped frame, and a slide table 2 is slidably provided on the upper and lower sides of the frame 1, and a hydraulic cylinder 3 for sliding the slide table 2 is built in. There is. A table 4 is arranged almost perpendicularly to the frame 1, and a tailstock center 5 is slidably provided on the table 4, and a hydraulic cylinder 6 for sliding the tailstock center 5 is built into the table 4. , also frame 1
A fixing center 7 is provided on the side wall of the holder, facing the tailstock center 5.

Further, rack dies 8 are mounted on the upper and lower slide tables 2, respectively, so that the teeth thereof face each other. The rack die 8 is constructed by arranging a tooth group 8a, a finishing tooth group 8b, and a relief tooth group 8c in sequence, and the tooth group 8a is used for plastic working of the workpiece. The height is gradually increased, and the length is 3.
The length of rotation is set, and the finishing tooth group 8b finishes the tooth profile of the workpiece created by the biting tooth group 8a.

The lower rack die 8 is provided with a limit switch 9 for detecting the tip positions of its biting teeth 8a, finishing teeth 8b, and relief teeth 8c, and the table 4 receives signals from the limit switches 9 to adjust the tailstock center. An automatic pressure regulating valve 10 is provided to adjust the supply of hydraulic pressure to the hydraulic cylinder 6 on the 5 side, so that the pushing force of the tailstock center 5 remains at the normal level until the biting teeth 8a of the rack die 8 engage. When the biting tooth 8a engages, the pushing force F1 increases smoothly, and when the finishing tooth 8b engages, it smoothly increases to the first setting pushing force F2 (>F1), and when the finishing tooth 8b engages, it smoothly decreases to the second setting pushing force F3. When the relief tooth 8c engages with (F2>F3>F1), the normal pushing force F1 is controlled.

Next, the operation will be explained.

When rolling a helical gear, for example, a helical gear 12 of a main drive shaft 11 as shown in FIG. , activate the device. Then, the hydraulic cylinder 6 on the tailstock center 5 side operates,
The workpiece 11 moves toward the fixed center 7 together with the tailstock center 5, and the workpiece 11 moves toward the fixed center 7 together with the tailstock center 5.
When the die is rotatably supported by the die, the hydraulic cylinder 3 on the die side is activated, and the upper and lower die 8 are moved in opposite directions. In this die 8, the workpiece 11 is first subjected to rolling compression molding by the teeth of the biting tooth group 8a, and a substantially predetermined gear shape is created during three rotations by the biting tooth group 8a, and then finished. The helical gear 12 is formed on the main drive shaft 11 after finishing molding with the tooth group 8b and passing through the relief tooth group 8c.

At this time, in this device, the pushing force of the tailstock center 5 gradually increases from the normal pushing force F1 at the initial stage of engagement between the biting teeth 8a of the rack die 8 and the workpiece 11, so that the workpiece 11 Fixed center 7
It does not move to the side, and the biting tooth 8a and workpiece 1
1 and 1 are engaged accurately and reliably without causing any misalignment, and when both are engaged, the pushing force of the tailstock center 5 becomes a pushing force F2 that is larger than the normal pushing force F1, and the rotation occurs. Movement of the workpiece 11 due to the axial component of the force acting on the workpiece 11 during shaping is suppressed, thereby creating a helical gear 12 in the workpiece 11 with high precision. Furthermore, the pushing force of the tailstock center 5 during finishing with the finishing tooth group 8b becomes a pushing force F3 which is larger than the normal pushing force F1 and smaller than the pushing force F2 when the biting teeth 8a are engaged. Movement of the workpiece 11 due to the axial component of the force acting on the workpiece 11 is suppressed, and the workpiece 11 can be finished with high precision.

In the apparatus of this embodiment as described above, the pushing force of the tailstock center is increased during forming using the biting teeth and finishing teeth, so that movement of the workpiece in the axial direction can be suppressed and the helical gear can be rotated with high precision. In addition, as a result of adjusting the pushing force of the tailstock center to suppress the movement of the workpiece, the workpiece can rotate freely, and the workpiece and center There is also little risk of burn-in occurring during the process.

In addition, in this device, the pushing force of the tailstock center is gradually increased at the initial stage of engagement of the biting teeth, which gradually increases in height, so this pushing force causes the workpiece to move toward the fixed center. There is no movement, and the die and workpiece can be engaged accurately and reliably.

In the above embodiment, the pushing force of the tailstock center is adjusted by detecting the position of the rack die, but the pushing force may be adjusted using a timer or the like in accordance with the moving speed of the rack die. Further, the pushing force at the initial stage of engagement of the biting teeth may not be gradually increased, but may be set to a constant predetermined pushing force smaller than the pushing force during rolling pressure molding of the biting teeth.

〔Effect of the invention〕

As described above, according to the helical gear rolling device according to the present invention, the pushing force of the center on the axially displaced side of the work is applied to the biting teeth of the rolling die whose tooth height gradually increases. The engagement area is larger than when supporting the workpiece, and the finishing tooth engagement area is set smaller than the biting tooth engagement area, so misalignment is prevented at the initial stage of engagement, ensuring accurate and reliable engagement. This has the effect of suppressing the axial displacement of the workpiece during molding, improving tooth profile accuracy, and preventing seizure between the workpiece and the center.

[Brief explanation of the drawing]

1 and 2 are respectively a front view and a side view of a helical gear rolling device according to an embodiment of the present invention, FIG. 3 is a diagram showing the relationship between the die position and pushing force of the device, and FIG. 4 Figure 5 shows an example of a workpiece.
The figure is a diagram for explaining a conventional technique. 5... Center, 8... Rolling die, 8a... Biting tooth, 11... Work.

Claims (1)

[Claims] 1. A workpiece is supported by a center between a pair of rolling dies, the rolling dies are moved relative to each other, and the rolling dies are engaged with the workpiece to form a helical gear on the outer peripheral surface of the workpiece. The device has a rolling die with a tooth group with biting teeth whose height gradually increases in the front half and a finishing tooth group in the rear half, and the pushing force of the center on the side of displacement in the axial direction of the workpiece is The biting tooth engaging area of the rolling die is larger than when supporting the work, and the finishing tooth engaging area is set smaller than the biting tooth engaging area. Helical gear rolling equipment.