JP4489255B2 - Turret lathe hobbing unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hobbing unit that enables gear cutting on a workpiece on a lathe, and is particularly mounted on the turret of a lathe provided with a turret that allows a plurality of tools to be selected by a turning indexing operation. It relates to the hobbing unit used.
[0002]
[Prior art]
In order to meet the demand, there is a lathe equipped with a hobbing unit for gear machining on the lathe turret in order to meet the demand. Proposed. The hobbing unit performs gear cutting by rotating the hob cutter supported by the unit synchronously with the main spindle rotation at a constant rotation ratio, but the hob cutter is compared to tools, drills, milling cutters, etc. In addition, the tool itself is large, and the direction of the rotation axis of the cutter is different from that of a drill or milling cutter, and the angle of the cutter relative to the workpiece must be changed depending on the gear module to be processed. Therefore, the hobbing unit has a complicated structure and a large unit.
[0003]
The simplest structure for mounting a hobbing unit on a lathe is a structure in which a tool post for the hobbing unit is provided separately, but the disadvantage is that the lathe becomes larger and the structure of the lathe itself becomes complicated. Absent. The lathe currently widely used for machining general-purpose workpieces is a turret lathe equipped with a turret tool post that can also be fitted with rotating tools such as drills and milling cutters. For example, the structure disclosed in Japanese Examined Patent Publication No. 7-53323 and the structure shown in FIG. 2 follow this concept. In the structure shown in FIG. 2, the rotation of the intermediate shaft 41 in the radial direction of the turret supported by the drive housing 40 attached to the tool mounting station of the turret 2 is orthogonal to the intermediate shaft by the bevel gear pairs 42a and 42b. The rotation of the second intermediate shaft 43 is transmitted to the cutter shaft 27 by the spur gears 44a and 44b, and the hob cutter 26 fixedly attached to the cutter shaft is rotationally driven. Structure. The hob cutter 26 is pivotally supported in a plane perpendicular to the radial axis on the radial extension of the tool mounting station on which the drive housing 40 is mounted. The intermediate shaft 41 is connected to the tool drive shaft in the turret 2 when the drive housing 40 is fitted to the tool mounting station A. Further, the hob cutter 26 can change the angle with respect to the workpiece by rotating the cutter bracket 46 pivotally supporting the hob cutter 26 about the axis of the intermediate shaft 41.
[0004]
[Problems to be solved by the invention]
Machine tools are required to improve machining efficiency and machining accuracy. In order to efficiently perform highly accurate machining, it is necessary to have rigidity to hold the blade in an accurate position even when a large cutting reaction force is applied. In order to increase the support rigidity of the blade supported by the turret, it is necessary to minimize the amount of protrusion of the blade from the turret. When the cutting edge of the tool greatly protrudes from the turret, the protruding portion is deflected by the cutting reaction force acting on the cutting edge, and when it is severe, the cutting edge vibrates and high-precision machining becomes impossible. Further, since the turret turns when the tool is indexed, it is desirable that the support member of the tool be as light and compact as possible.
[0005]
From this point of view, when the conventional hobbing unit is viewed, for example, in the one disclosed in Japanese Examined Patent Publication No. 7-53323, the hob cutter is pivotally supported by one-side support, so that sufficient support rigidity cannot be obtained. The drive mechanism of the cutter is also complicated. A further problem is that it is difficult to change the inclination angle of the hob cutter with respect to the workpiece, and there is an inconvenience that a module of a gear to be processed is fixed, and a dedicated processing unit must be prepared for each gear of the module.
[0006]
On the other hand, the structure shown in FIG. 2 makes it easy to change the angle of the hob cutter. Therefore, if the hob cutter 26 is replaced and the attachment angle of the cutter bracket 46 to the turret is changed, the gears of different modules can be processed. However, since the bevel gear pair 42 and the second intermediate shaft 43 are interposed between the outer periphery of the turret and the hob cutter, the overhang amount of the hob cutter 26 from the outer periphery of the turret 2 is increased. There is a problem that when the support rigidity of the cutting edge is reduced and a large cutting reaction force is applied, the cutter is easily bent or vibrated.
[0007]
The present invention has been made to solve the above problems, and basically has a structure capable of changing the angle of the hob cutter with respect to the workpiece, and can be mounted closer to the outer periphery of the turret. Therefore, it is an object of the present invention to provide a turret-mounted hobbing unit capable of machining with higher precision under a large cutting reaction force with a high cutting edge rigidity.
[0008]
[Means for Solving the Problems]
The hobbing unit of the invention of this application is mounted on the turret 2 using two or three tool mounting stations adjacent or close to the turret. In general, two adjacent tool mounting stations may be used, or a structure in which three tool mounting stations are mounted when a large hob is used or when a higher support rigidity is desired may be employed.
[0009]
The hobbing unit of the invention of this application is constituted by a plurality of units equal in number to the tool mounting stations used. The base unit 4 as the first unit includes at least a base housing 8 fitted to the first tool mounting station A of the turret, and a pickup shaft 10 pivotally supported by the base housing 8 so as to be freely rotatable. When the base housing is mounted on the tool mounting station, the pickup shaft 10 has an engagement portion 13 that engages with a tool drive shaft built in the turret 2 and one of gear pairs 14a that transmits rotation to an intermediate shaft described later. Provided. When the hobbing unit is formed of two units, a base plate 9 for fixing a cutter bracket 23 (to be described later) integrally with the base housing 8 is provided. This base plate is located on the outer peripheral surface of the turret 2.
[0010]
The main unit, which is the second unit, includes a drive housing 15 that is inserted into the second tool mounting station B adjacent to the first tool mounting station, and a cutter bracket that supports the cutter shaft 27 of the hob cutter 26. . The cutter bracket 23 is separable from the drive housing 15 or is swingably connected around a fulcrum shaft 21 described later.
[0011]
The drive housing 15 supports an intermediate shaft 17 so as to be freely rotatable. The intermediate shaft 17 has one of a gear 14b that meshes with the gear 14a of the pickup shaft and a second gear pair that drives the fulcrum shaft 21. 20a.
[0012]
The fulcrum shaft 21 is pivotally supported by the drive housing 15 or the cutter bracket 23 or the drive housing and the cutter bracket so as to be freely rotatable. The fulcrum shaft 21 is in parallel with the radial axis of the first tool mounting station A, that is, parallel to the X axis when the first tool mounting station is indexed toward the workpiece, and meshes with the gear 20a of the intermediate shaft. A gear 20b that rotates and a gear pair 30a that drives the cutter shaft are provided.
[0013]
The cutter bracket 23 pivotally supports a cutter shaft 27 on both sides of the hob cutter 26, and a gear 30b that meshes with a gear 30a of a fulcrum shaft is provided at one shaft end. The cutter bracket 23 is fixedly attached to the base plate 9 in a state where the axis of the fulcrum shaft 21 is aligned by a short cylindrical surface fitting structure (infrared) having the fulcrum shaft 21 as an axis. This fixing is performed by the fixing bolt 31. By loosening the fixing bolt 31, the cutter unit 7 can change the angular position around the fulcrum shaft 21. This change in angle can be realized by making the insertion hole of the fixing bolt 31 on the cutter bracket 23 side an arc hole centered on the fulcrum shaft 21 or providing a plurality of fixing bolt insertion holes.
[0014]
The base plate 9 for fixing the cutter bracket 23 can also be mounted on a third tool mounting station C adjacent to the first tool mounting station on the opposite side of the second tool mounting station. In this case, a fixed unit as a third unit is provided separately. This fixed unit includes a fixed housing that is inserted into the third tool mounting station C, and a base plate integrated therewith. The outer surface of the base plate is a plane orthogonal to the axis of the fulcrum shaft 21, but is a rotation surface having the fulcrum shaft 21 as the axis. When this third unit is provided, the cutter bracket 23 is fixedly attached to the base plate of the third unit and the drive housing of the second unit with fixing bolts.
[0015]
In the hobbing unit according to the invention of this application, the base unit 4, the main unit 5, and the third unit constituting the hobbing unit are individually mounted on the tool mounting station of the turret. In this mounted state, the pickup shaft 10 pivotally supported by the base housing is connected to the tool drive shaft inside the turret 2, and the hob cutter 26 drives the tool inside the turret via the pickup shaft 10, the intermediate shaft 17 and the fulcrum shaft 21. It is rotationally driven by the shaft. Accordingly, if the tool drive shaft of the turret is synchronized with the rotation of the main shaft of the lathe and rotated at a predetermined rotation speed ratio, the rotation of the hob cutter and the workpiece necessary for gear cutting can be synchronized. As described above, the angle of the hob cutter 26 relative to the workpiece can be changed by swinging the cutter bracket 23 around the fulcrum shaft 21 and fixing it to the base plate. And in the structure according to the present invention, there is no gear pair or intermediate shaft for driving the hob cutter between the hob cutter and the outer periphery of the turret, so the hob cutter 26 can be mounted close to the outer periphery of the turret 2, Further, by fixing the cutter bracket 23 using a plurality of tool mounting stations, high support rigidity of the hob cutter 26 can be ensured.
[0016]
In practice, this is not a very preferable structure, but if the tool drive shaft in the turret is a turret that is configured to rotate all the rotary tools mounted on the turret at the same time, the pickup shaft and the pickup shaft are intermediate. It is also possible to adopt a structure in which the bevel gear fixed to the inner end of the intermediate shaft is meshed with the bevel gear integrated with the turret center rotation shaft without providing the gear pairs 14a and 14b for meshingly connecting the shafts. In this case, the hobbing unit of the invention of this application can be constituted by the main unit and the fixed unit as the third unit without providing the first base unit.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the hobbing unit of the present invention will be described in detail with reference to the embodiment shown in FIG. The lathe turret 2 to which the hobbing unit 1 shown in the figure is mounted is provided with twelve tool mounting stations, and the two adjacent tool mounting stations A and B are used as relative signs. A hobbing unit 1 is attached. Although some turrets have a structure in which a rotary tool such as a drill or a milling cutter is supported in a direction parallel to the support shaft, the turret shown in FIG. 1 has a structure in which these rotary tools are mounted in a radial direction. . In the turret 2, a tool drive shaft 3 is provided that faces the workpiece direction (X-axis direction) regardless of the indexing rotation of the turret 2. Since this tool drive shaft mounting structure and drive means are already known, they are omitted here. The tool attachment stations A and B may or may not be a rotary tool attachment station, but at least the turret 2 needs to be provided with a drive means for the rotary tool.
[0018]
The hobbing unit 1 shown in FIG. 1 includes a base unit 4 and a main unit 5, and the main unit 5 includes two subunits, a drive unit 6 and a cutter unit 7. The base unit 4 includes a base housing 8 fitted to the first tool mounting station A and a base plate 9 integrated with the base housing 8, and a turret radial pickup shaft 10 is provided at the center of the base housing 8 with bearings 11, 12. It is pivotally supported so that it can freely rotate. An engagement portion 13 that engages with the tool drive shaft 3 is formed at the inner end of the pickup shaft 10, and one side 14 a of the first bevel gear pair is fixed adjacent thereto. The engaging portion 13 in the illustrated embodiment is a ridge in the diameter direction of the pickup shaft 10. The base housing 8 and the base plate 9 integrated therewith are fixed by fixing the base plate 9 to the outer periphery of the turret 2 with bolts (not shown).
[0019]
The drive unit 6 includes a drive housing 15 that is inserted into the second tool mounting station B, and a support base 16 that is integral therewith. An intermediate shaft 17 is rotatably supported by bearings 18 and 19 in the drive housing 15, and a bevel gear 14 b forming a first gear pair with the bevel gear 14 a is fixed to the inner end of the drive housing 15. One of the gears 20a forming the second bevel gear pair is fixed to the outer end thereof. The outer surface of the support base 16 is a plane perpendicular to the radial axis of the first tool mounting station, and is formed with a short cylindrical fitting hole 22 coaxial with a fulcrum shaft 21 described later. This drive unit is fastened and attached to the outer periphery of the turret with a bolt (not shown).
[0020]
The cutter unit 7 includes a U-shaped cutter bracket 23, and this cutter bracket supports both ends of a cutter shaft 27 to which a hob cutter 26 is fixed by bearings 24 and 25 so as to freely rotate. A fulcrum shaft 21 in a direction perpendicular to the cutter shaft is supported by bearings 28 and 29 on one end side of the cutter shaft, and the fulcrum shaft 21 and the cutter shaft 27 are driven and connected by bevel gears 30a and 30b at right angles. Yes. A part of the outer ring of the bearings 28 and 29 supporting the fulcrum shaft 21 protrudes from the surface of the cutter bracket 23 facing the support base 16, and this protruding portion is fitted into the fitting hole 22 of the support base. As a result, the cutter bracket 23 is coupled to the drive housing 15 so that the angle of the cutter bracket 23 can be adjusted around the fulcrum shaft 21. A bevel gear 20b that meshes with the bevel gear 20a of the intermediate shaft 17 to form a second bevel gear pair is fixed to the inner end of the fulcrum shaft 21. The cutter bracket 23 is fastened and attached to the base plate 9 and the support base 16 by a plurality of fixing bolts 31 shown in the drawing. The bolt holes on the cutter bracket 23 side of these fixing bolts 31 are arc holes centered on the fulcrum shaft 21 so that the angular position of the cutter bracket 23 around the fulcrum shaft 21 can be adjusted.
[0021]
The hob cutter 26 attached to the turret 2 in this way is attached to the turret 2 with the cutter bracket 23 fixed at an angle corresponding to the lead of the hob cutter 26, and the hob cutter 26 is attached to the workpiece by the indexing operation of the turret 2. In the state of being opposed to each other, the main shaft for gripping the workpiece and the tool driving shaft 3 are rotated at a predetermined rotation speed ratio, and cutting feed is given by the tool post to perform gear cutting.
[Brief description of the drawings]
FIG. 1 is a cross-sectional side view showing an embodiment of the present invention mounted on a turret. FIG. 2 is a cross-sectional side view showing an example of a conventional hobbing unit mounted on a turret.
15 Drive housing
17 Intermediate shaft
21 fulcrum shaft
23 Cutter bracket
26 Hob Cutter
27 Cutter axis

Claims (2)

A cutter bracket (23) pivotally supporting a hob cutter (26) mounted on a radial extension of the first tool mounting station of the turret, and mounted on a second tool mounting station adjacent to the first tool mounting station Drive housing (15), an intermediate shaft (17) that is pivotally supported by the drive housing and connected to the tool drive shaft of the turret when the drive housing is mounted, and an intermediate shaft ( 17) and a hobbing unit for a turret lathe, comprising a fulcrum shaft (21) parallel to the radial axis of the first tool mounting station meshingly connected to the cutter shaft (27). A hob cutter (26) mounted on the radial extension of the first tool mounting station of the turret is pivotally supported by a drive housing (15) mounted on a second tool mounting station adjacent to the first tool mounting station. Through an intermediate shaft (17) connected to the rotary tool drive shaft of the turret and a fulcrum shaft (21) meshed with the intermediate shaft and supported in parallel with the radial axis of the first tool mounting station. Turret lathe hobbing unit, characterized by being driven by

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