EP2794168A2

EP2794168A2 - Method for producing a toothing

Info

Publication number: EP2794168A2
Application number: EP12822959.8A
Authority: EP
Inventors: Marc Gareis; Klaus Wilczek
Original assignee: Losomat Schraubtechnik Neef GmbH
Current assignee: GEDORE TORQUE SOLUTIONS GMBH
Priority date: 2011-12-21
Filing date: 2012-12-12
Publication date: 2014-10-29
Also published as: WO2013091602A2; BR112014015414A8; CN104114308A; BR112014015414A2; CN104114308B; RU2609110C2; RU2014129567A; US20140369777A1; WO2013091602A4; DE102011121784A1; WO2013091602A3

Abstract

A method for producing a toothing on an in particular round workpiece, wherein the teeth are produced by a shaping method using a tool which moves along a path which is controlled by a lifting cam and in the case of which an exchange movement that runs substantially in the radial direction of the workpiece follows a downward movement which runs in the axial direction of the workpiece and serves to produce the tooth flanks, wherein the exchange movement is superimposed with a downward movement such that a curved path is produced during the exchange, is characterized in that the relative rake angle γ_rel of the tool (200) does not fall below a minimum rake angle γ_min which corresponds to the rake angle γ of the tool (200), said rake angle γ being reduced by the angle δ between the longitudinal axis of the workpiece and the direction vector of the tool movement.

Description

Method for producing a toothing

The invention relates to a method for producing a toothing on a particular round workpiece, wherein the teeth are produced by a Abwälzstoßverfahren with a tool that moves a controlled by a lift cam track, in the tooth flank serving, extending in the axial direction of the workpiece downward movement obliquely to the downward movement and substantially in the radial direction of the workpiece extending exchange movement follows.

State of the art

From the prior art, in particular for the production of gears Abwälzfräs- or Abwälzstoßverfahren known. With the help of Abwälzstoßverfahren outer and internal gears can be produced for example in cylindrical bodies. In this case, successive Abwälzstoßvorgänge be made at long axial tooth flanks. This is commonly referred to in the art as "shuttle bumping." In a downwards bumping operation, the tool passes through a pathway that traverses a downward movement of the workpiece in the axial direction of the workpiece.

CONFIRMATION COPY Traces an obliquely to the downward movement and extending substantially in the radial direction of the workpiece evacuation movement, which expires following the downward movement arcuately from the workpiece to be machined. During the last stroke, the contour of the workpiece is selected such that the tool (impact tool) runs axially out of the contour of the workpiece to be produced. For this reason, design notches are provided at the end of the tooth flanks, so punctures that protrude at least so deep into the workpiece that they end at least at the tooth base. Such construction notches now represent a weakening of the workpiece, which should be avoided especially at high loads, which such gears are exposed, for example, in power robberies.

Furthermore, it is known, for example, from JP 01-115513 A, to produce a toothing on a round workpiece by the teeth are produced by a Abwälzstoßverfahren with a tool that travels a controlled by a lift-off cam, in one of the tooth flank manufacturing serving, in Downward movement of the workpiece in the axial direction of the workpiece follows a substantially extending in the radial direction of the workpiece immersion movement, wherein the Ausbewegungbewegung is superimposed by a downward movement so that there is a curved path during the Austauchen. Although no design notches are produced, but a curved transition at the end of the tooth flanks, there is a risk that the tool wears very quickly in this process.

The invention is therefore based on the object to provide a method for producing a toothing in a particular round workpiece, which avoids construction notches in the manufacture of the teeth, and which is feasible without significant wear of the tool. Disclosure of the Invention Advantages of the Invention

This object is achieved by a method for producing a toothing of the type described above, in which the Austauchbewegung is superimposed by a downward movement so that there is a curved path during the Austauchen. The relative rake angle γ _{Γ (5} ι of the tool does not fall below a minimum rake angle Y _min , which corresponds to the rake angle γ of the tool, which is reduced by the angle δ between the longitudinal axis of the workpiece and the direction vector of the tool movement According to the invention, the angle between the surface of the tool and a straight line which is perpendicular to the direction vector of the tool's _{displacement movement} is understood to be the angle of _incidence γ. The angle δ can be, for example, an arctangent of the time derivative of the radial component divided by the time derivative of the axial component the direction vector of the tool movement are determined.

By this measure can be dispensed with very advantageous to an undercut on the outlet of the tooth flanks. Rather, by the superimposition of the downward movement and the exchange movement and the choice of the radius, so to speak, a curved transition at the end of the tooth flanks is achieved, which, in contrast to an undercut there arranged even allows thickening of the material and thus an increase in stability. This is possible without a greater wear of the tool, as it would be possible in a production of the toothing using an undercut.

The measures listed in the dependent claims advantageous refinements and improvements of the independent claim method are possible. In principle, the radius with which the tool is moved during the immersion movement can be selected and set. A very advantageous embodiment of the method provides that the transition from the downward movement in the Austauchbewegung takes place continuously and steadily with a very small radius.

Preferably, the angle between the downward direction of travel and the direction of intermittent movement at the end of the tooth flank is slightly more than 90 °. The tool is thus not moved at the end of the tooth flank in the radial direction, but the radial direction is superimposed on an axial direction, i. The tool is seen in the axial direction of the workpiece obliquely down or moved upwards. This results in a continuous curved outlet of the tooth flanks and thus the desired increase in stability in the region of the end of the tooth flanks and thus at the end of the toothing.

For the production of internal gears in particular, the use of a tool designed as a bell wheel has proved to be particularly advantageous. With such a bell wheel, internal gears can be produced by the aforementioned shuttle beating in a simple, quick and precise manner.

In a corresponding manner, external teeth can also be produced with the aid of such a bell wheel, in which case simultaneous rotation of the workpiece during the machining process is required.

The workpiece may have a diameter which changes at a point of the workpiece at least half the diameter of the tool. Typical tool diameters range from 20 mm to 25 mm. With conventional hobbing or hobbing methods it is not possible to workpieces with such a large diameter change to produce an external toothing, which ends in the range of the diameter change, since in this case no safe replacement of the tool is possible.

The workpiece itself preferably has a cylindrical profile or a hollow cylindrical profile.

If the workpiece is designed as a hollow cylinder in which an internal toothing is to be produced, it is possible with the method according to the invention that its teeth have a tooth height which corresponds at least to the diameter of the cavity or cup in the hollow cylinder.

The workpiece is preferably made of a high strength, high performance aluminum alloy.

Such aluminum alloys are particularly easy to work with the help of the aforementioned Abwälstoßstoßens. But it is also a machining of existing steel workpieces possible.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. In this case, features taken individually or combined with each other may be important. Show it:

1 is a schematic sectional view of a workpiece in which the teeth have been produced by manufacturing processes known from the prior art;

FIG. 2 shows a detail enlargement of the area indicated by II in FIG. 1; FIG. Fig. 3 is a comparable to Figure 1 workpiece, in which the internal and external teeth was produced by means of the method according to the invention.

FIG. 4 shows a detail enlargement designated IV in FIG. 3; FIG.

5 is a schematic representation of the method according to the invention prior to the start of the lifting movement of the tool;

Fig. 6 is a schematic representation of the method according to the invention during the lifting movement of the tool;

Fig. 7 is a schematic representation of the method according to the invention at the end of the lifting movement of the tool and

8 is an illustration of the tool stroke on the lifting movement of the

Tool cam in one embodiment of the invention

Process.

Description of exemplary embodiments

A workpiece designated 100 as a whole is designed, for example, as a hollow cylinder. At its one end, the hollow cylinder 105 has an internal toothing 110. At its other end an outer toothing 150 is provided. Both the outer and the inner toothing are characterized in that in each case at its one end in the case of the internal toothing 110 an undercut 115 and in the case of the external toothing 150 an undercut 155 is provided. This is because both the internal gear 110 and the external gear 150 are formed by a hobbing method in a known manner with the aid of a tool which travels a path controlled by a lift-off cam, in which a tooth flank manufacturing downward movement running in the axial direction of the workpiece the tool follows an obliquely to the downward movement and extending substantially in the radial direction of the workpiece exchange movement. The tool thus runs linearly in the axial direction over a relatively long period of time and then turns into a curved arcuate movement in order to dive out of the workpiece again. such Rolling processes are carried out consecutively with long gears. This consecutive "shuttle-like" sequence of downslope operations is referred to as "shuttle beating." In this case, the type of superposition of the downward movement, ie the movement of the tool in the axial direction of the workpiece and the Austauchbewegung, ie the movement of the tool obliquely to the downward movement is irrelevant, as by a second, following a Abwälzstoßvorgang Abwälzstoßvorgang unwanted material projections due to the arcuate movement of the Tool be eliminated in the machined workpiece by then at this point subsequent downward movement. For this reason, each of the undercut 1 15 and 155 is provided at the end of the tooth, which must be so deep and must be formed so long in the axial direction that the arcuate movement of the tool, so for example a bell wheel, so far taken into account in that a "non-contact" exchange movement is possible at the end of the tooth flank.

Such an undercut 1 15, which must protrude so far into the workpiece at least in the radial direction that it is at least as deep as the tooth base and must be formed in the axial direction of the workpiece so long that at the end of the tooth flank still a downward movement of the tool exists is weakens the workpiece at the end of the gearing.

The basic idea of the invention is now to process such a rolling stroke and, in particular, to develop a so-called shuttle beating in such a way that it is possible to dispense with an undercut completely. The method is explained below in connection with FIG. 3 and FIG. 4, wherein the same elements are provided with the same reference numerals as in FIG. 1 and FIG. 2. Again, a hollow-cylindrical workpiece 100 is provided, which has different diameters in an area an internal toothing 120, the tooth flanks of the internal teeth 110 correspond, is provided and in the other area an external toothing 160, whose tooth flanks in turn correspond to those of the external toothing 150. In contrast to the teeth shown in Fig. 1 and Fig. 2, however, no undercut is provided here. Rather, the teeth are curved at their respective ends in regions 122 and 162, respectively. This curved leakage is produced by superimposing the downward movement of the tool on a downward movement in such a way that a curved path results during the replacement. This curved path can be seen particularly clearly in the detail enlargement of FIG. 4. It is provided in the internal teeth with the reference numeral 122 and in the external teeth by the reference numeral 162. The transition from the downward movement in the axial direction of the workpiece 100 in the Austauchbewegung, ie substantially obliquely to the axial direction and almost in the radial direction of the workpiece 100 is carried out continuously and steadily with a very small radius. It is provided that in the region of the tooth flanks, the angle between the downward movement and the exchange movement is slightly greater than 90 °, ie the exchange movement takes place in the region of the tooth flanks not in the radial direction, but obliquely to the radial direction, but with a very small angle. In this way, results in the areas of the ends of the tooth flanks 122, 162 an oblique course, which allows at this point, in contrast to the prior art, no material thinning, but even a material thickening and thus at the same time simplifying production has an increase in stability result ,

FIG. 5 shows how a tooth flank 122 can be produced by means of the method according to the invention. A tool 200 acts at a clearance angle α to the tooth base 124 on the surface or inner surface of the hollow cylinder 105 a. The clearance angle α thus describes the angle of the free space between the tool 200 and the surface to be machined. This tool 200 is wedge-shaped and its cutting edge has a wedge angle ß. The angle between the surface of the tool 200 and a straight line perpendicular to the tooth root 124 is referred to as the rake angle γ. It influences the compression and drainage of a chip, as well as the heat distribution during machining. This rake angle γ is dependent on the Hardness of the hollow cylinder material selected. The sum of the clearance angle α and the wedge angle β is referred to as the cutting angle. The sum of the clearance angle a, the wedge angle ß and the rake angle γ is 90 °. Up to a point A, up to which the tooth flank 122 is to run parallel to the longitudinal axis of the hollow cylinder 105, the tool 200 cuts at a first cutting speed v _cA parallel to the longitudinal axis of the hollow cylinder 105. The relative rake angle γ _Γβ ι in this case corresponds to the rake angle γ.

With the beginning of the exchange movement, the direction vector of the cutting movement deviates from the longitudinal axis of the hollow cylinder 105. This takes place, for example, at a point B with a second cutting speed V _C B, which is shown in FIG. 6. Fig. 7 shows the tool at a point C at the end of the exchange movement. The distance between the points A and C, ie between the beginning and the end of the exchange movement is referred to as outlet a. The distance between the points A and C in the radial direction, which is due to the stroke of the tool 200, is indicated in FIG. 7 as t. At point C, the tool 200 has a third cutting speed v _cC .

The relative rake angle γ _Γβ ι corresponds to the angle between the surface of the tool 200 and the straight line, which is perpendicular to the direction _{vector of the exchange} movement of the tool. It is shown in FIGS. 6 and 7 for points B and C.

The permissible minimum value Y _{min of} the relative rake angle γ _Γβ ι is calculated according to formula 1 in each point of the exchange movement as the difference between the rake angle γ and the angle δ between the direction _{vector of} the movement of the tool 200 and the longitudinal axis of the hollow cylinder 105:

Yrel * Ymin (Formula 1) Falling below this minimum value Y _{min there} is an increased risk that the tool 200 breaks.

In FIG. 7, the relative rake angle y _re i at point C corresponds exactly to its permissible minimum value Y _min .

The angle δ can according to formula 2 as an arctangent of the time derivative of the axial component y divided by the time derivative of

Radial component x of the direction vector of the tool movement are determined:

δ (formula 2)

In this context, the directional vector is understood to be the vector which can be applied to the tooth base as a tangent, ie, in the points B and C, the vector of the velocity V _C B and v _cC, respectively, at each point of the _{exchange movement} . Before the beginning of the exchange movement, the direction vector runs parallel to the longitudinal axis of the hollow cylinder 105 and thus corresponds to the vector of the velocity v _c c-

The movement of the tool 200 is controlled via a lift-off cam. FIG. 8 shows the stroke t of the tool 200 as a function of the lift Ab of the lift-off cam in an embodiment of the method according to the invention.

The preparation of the tooth flanks, in particular the internal toothing can - be made with the aid of a bell wheel - as already explained above. In this case, long teeth can be produced with the help of the above-described shuttle bumping. Aluminum and aluminum alloys prove to be particularly advantageous for the application of the method according to the invention. In principle, however, it can also be used with steels. A typical rake angle γ for aluminum is 25 °, while a common rake angle γ for steel is 10 °.

Claims

claims

1 . A method for producing a toothing on a particularly round workpiece (100), wherein the teeth (120) are produced by a rolling-off method with a tool (200) which descends a path controlled by a lift-off cam, in the axial direction for tooth flank production Downward movement of the workpiece (100) is followed by an exchange movement extending substantially in the radial direction of the workpiece (100), the removal movement being superimposed by a downward movement such that a curved path results when exiting, characterized in that the relative rake angle γ _Γβ ι des Tool (200) does not fall below a minimum rake angle Y _min , which corresponds to the rake angle γ of the tool (200), which is reduced by the angle δ between the longitudinal axis of the workpiece (100) and the direction vector of the tool movement.

2. The method according to claim 1, characterized in that the angle δ as an arctangent of the time derivative (y) of the

Axial component divided time derivative (x) of the radial component of the direction vector of the tool movement is determined.

3. The method according to claim 1 or 2, characterized in that the transition from the downward movement in the Austauchbewegung takes place with a very small radius.

4. The method according to any one of the preceding claims, characterized in that the angle between the downward movement and the exchange movement is slightly greater than 90 °.

5. The method according to any one of the preceding claims, characterized in that the tool (200) is a bell wheel.

6. The method according to claim 5, characterized in that the workpiece (100) has a diameter which changes at a position of the workpiece (100) at least by half the diameter of the tool (200).

7. The method according to any one of the preceding claims, characterized in that the workpiece (100) has a cylindrical profile or is formed by a hollow cylinder.

8. The method according to claim 7, characterized in that the workpiece (100) is designed as a hollow cylinder in which an internal toothing (120) is produced, whose teeth (120) have a tooth height which corresponds at least to the diameter of the cavity in the hollow cylinder ,