DD156581A5 - METHOD FOR REMOVING CRANKS AND CAMSHAFTS - Google Patents

Abstract

The invention relates to a method and a device for milling crankshafts or camshafts. The aim of the invention is to achieve particularly good machining tolerances without straightening process and with only small grinding allowances. The invention has for its object to provide a method that makes its own, subsequent to the milling straightening process unnecessary and largely allow grinding allowances to reduce, as well as to provide a suitable for carrying out this method Luenette. Z. Solution of this problem, the wave at the respective Abstuetzstelle without a centering in the just assumed by her situation actually stretched and in this position, the processing of the shaft journal od. Like. Carried out. A suitable Luenette has clamping jaws, which can be clamped individually and independently of one another in any position via clamping devices.

Description

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Title of the invention

J Method and device for milling crankshafts or camshafts

'Field of the invention

The invention relates to a method for milling Kurbelbzw. Camshaft, after which the workpiece is stretched at both ends and in the processing of the shaft journal od. Like. Is supported at least one point, and a steady rest for a milling machine for! Performing this method.

' Characteristic of the known solutions

Milling machines with one or two milling carriages are used for milling crankshafts or camshafts and the workpiece to be machined is supported via a single or double steady rest as close as possible to the respective machining location in order to achieve good cutting conditions and a corresponding machining accuracy. After a usual BearbeitungsverfahFen then the shaft journals od. Like., So for example, the journals and crank pins of a crankshaft, milled progressively from one to the other end, each of the just milled bearing pin is supported during the processing of the following pin. So far, now for supporting the journals self-centering

Lunettes in use, whereby the bearing pins are brought simultaneously with the support in a centered position and held in this. The workpiece is thus, even if it bends during machining by freeing of internal stresses, for each processing step repeatedly straightened, so that the position of the crank pin is ensured relative to the journals within a corresponding tolerance range. The disadvantage of this. However, processing method lies in the fact that the workpiece springs back into the bent position after completion and then eliminates this bending only by its own straightening process, which is not automatable and therefore very complicated and expensive, or by a grinding, which, however, requires extremely large grinding allowances can be.

Object of the invention

The aim of the invention is a method for! Milling of Kurbelbzw. Camshafts through which particularly good machining tolerances can be achieved in a rational manner without straightening process and with only small grinding allowances, as well as a steady rest for a milling machine with which such a milling process can be realized. ·

Explanation of the essence of the invention

The invention is based on the object, a method. admit that makes their own, subsequent to the milling. straightening process 'unnecessary' and allows to be provided for a possibly still required grinding process grinding allowances largely reduce. In addition, a bezel for a milling machine to be created, with which this milling process can be realized appropriately.

The invention solves this problem in that the shaft at the respective support point without a centering in the

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strained from her just actually taken situation and in this situation, the processing of the shaft journal od. Like. Is performed. Since the shaft is simply stretched during the support and thereby not directed or centered, it can not come after completion of the workpiece to a springback in a bent position, but the workpiece retains its resulting from the machining shape. This means that at least the unsupported shaft journal after machining in their exact, compared to the theoretical workpiece axis correct position, since the tool mills these pins as a fully centered shaft and therefore eliminates the resulting due to the released internal stresses bending , If the journals are supported during milling in the usual way and first all bearing journals and then the crank pins are processed, however, in the end the journals remain in their eccentricity, but then only with the journals a corresponding grinding allowance can be expected. If, on the other hand, not only crank pins but also bearing journals are machined during a trunnion support, similar conditions also arise for these trunnions as for the crank trunnions, as a result of which the deflections arising up to this machining are milled out on the trunnions and, after completion of the shaft, only relatively small bends remain. However, this bending must be eliminated after the milling process, since due to the lack of spring back no other eccentricities can arise more, and the elimination of this small bending is no problem. Since no centering takes place in the method according to the invention, but not always a bearing pin needs to be supported, but it can just as a crank pin or even a crank arm od. Like. Serve as a support point. Depending on the existing processing conditions, etc., therefore, the support points can be selected and the after milling the shaft still to be eliminated bends and thus the required grinding allowances influenced quantitatively and locally

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be restricted «,

The method according to the invention is not bound to a specific milling process, but can be applied to a wide variety of crankshaft or camshaft milling applications, ie both incremental milling of only one shaft journal each and stepwise milling of two pins in the support of only one or simultaneously of two shaft sections, with a permanent central support or with a likewise progressive support, with a milling with a pre- and a post-processing step or with a milling with only one step for finishing, etc. However, the application of the method will usually limited to short shafts, so on crankshafts or camshafts for car and truck engines, since it does not take into account the influence of slack due to the weight of the workpieces, which plays no role in short hamlets.

Since the shaft is supported without simultaneous centering, the method according to the invention also makes it possible to support unprocessed shaft sections, which makes expensive preparatory actions, such as the turning of a steady rest belt or the like, superfluous. In addition, there is a greater freedom in the assignment of support points against processing points.

In order to carry out the method easily, a steady rest with at least two actuators from each other position independent on the support points and applied after the application together pressureable jaws proposed in the development of the invention for a suitable milling machine, in which the jaws on them associated clamping devices independently in each Any position can be clamped. Since the shaft is to be tensioned without centering, the jaws must be able to be set individually

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and the required clamping pressure may only be applied after the application of all clamping jaws.

As actuators, on the one hand an unbound movement of the clamping jaws and on the other hand after placement on the workpiece enable a common clamping action of the jaws, are particularly hydraulic or pneumatic drives, which are interconnected or connected to a common Iruckmittelversorgung, which hydraulic or Pneumatic actuators bring the desired positioning effects without much design effort. The clamping devices simplify the support significantly, since they fix the acted upon by the actuators clamping jaws in their supporting position, the machining of the shaft in the desired sense but can be made with relieved actuators.

In order to be able to use the method according to the invention even when the workpiece is being turned during milling, the clamping jaws together with their actuating drives and clamping devices can be mounted in a rotatably mounted ring carriers surrounding the workpiece. As a result, the shaft can be eccentrically clamped at the support point, if necessary, and rotated despite this support for milling the shaft journal, because the ring carrier allows co-rotation of the clamping jaws with the workpiece. If the ring carrier is optionally fixable, of course, the steady rest can be used both for milling stationary and for milling driven shafts.

embodiment

The invention will be explained in more detail with reference to two schematically illustrated in the drawings embodiments. 1 shows a lunette in front view on the left half

for a milling machine for machining a rotating workpiece and on the right half a bezel for a milling machine for machining a stationary workpiece and

Pig. FIG. 2 shows an axial section through both exemplary embodiments according to the line II-II of FIG. 1. FIG.

A on the machine bed of a milling machine 1 longitudinally displaceable bezel 2, not shown further, 2a is ausgerütstet with three radially adjustable clamping jaws 3 ₅ 3, below which adjustment a respective hydraulic actuator 4, 4a is used. The hydraulic drives 4, 4a are above the lines 5? 5a in connection with each other and are supplied together with pressure medium. For fixing the individual clamping jaws 3, 3a in any position clamping devices 6, 6a are provided, which can be actuated hydraulically or mechanically.

For a milling machine for machining a stationary workpiece, the clamping jaws 3 are used directly in a steady-rest guide 7 and are simply adjusted radially via the hydraulic drives 4 (FIG. 1, right half, FIG. 2 lower half). For a milling machine for machining rotating workpieces, the clamping jaws 3a must be able to follow the movement of the workpiece (FIG. 1, left half, FIG. 2, upper half). In order to achieve this, these clamping jaws 3a, including their hydraulic drives 4a and the clamping devices 6a are mounted in a carrier 8, where they sit in a carrier-fixed guide-9 and are radially adjustable. The carrier 8 surrounds the workpiece to be machined and is rotatably mounted in the steady rest 2a. A gear 10 ensures the synchronized with the workpiece rotation drive of the carrier 8, so that during the machining of a workpiece, the support rotates according to the workpiece. To supply the hydraulic drives 4a open the lines 5a in an inlet 11 of the inserter 8, which in a manner not shown to a either accommodated in the carrier medium pressure medium

Supply or via a rotary feedthrough to a arranged outside the carrier pressure medium supply is connected.

The steady rest 2, 2a with its correspondingly adjustable clamping jaws 3, 3a allows the clamping of a workpiece 12 without centering it thereby, so that it can be fixed in an off-center position. As a result, it is possible, when milling crankshafts or the like, to support the shaft in the position actually present, in order to avoid its return springing into a bent position after completion of the crankshaft.

Claims (4)

Invention to saying: 1. A method for! Milling crankshaft or ilockewellen, according to which the workpiece is stretched at both ends and od in the processing of the journals. The like. At least one point is supported, characterized in that the shaft at the respective Support point without a centering in the position actually taken by her just stretched and in this position, the processing of the shaft journal od. Like. Is performed. , 2. The method according to item 1, characterized in that the shaft is fixed by supporting at least one of its journals in the existing position. 3. bezel for a milling machine for carrying out the method according to item 1 or 2 with at least two actuators from one another position independent attachable to the support points and after application jointly pressurizable jaws, characterized in that the clamping jaws (3, 3a) via them associated clamping devices ( 6, 6a) can be clamped individually and independently of each other in any desired position. 4. bezel according to item 3 », characterized in that the clamping jaws (3a) together with their actuators (4a) and clamping devices (6a) in a rotatably mounted, the workpiece (12) surrounding ring carrier (8) are mounted. ... oiL pages drawings.