JPS6333962B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In order to mill a crankshaft or a camshaft, the invention clamps the workpiece at both ends, and the bearings of the shaft (for example, crank journals and pins in the case of a crankshaft) or similar parts The present invention relates to a method for supporting a workpiece in at least one place during machining and forming, and a milling machine for carrying out this method.

For milling crankshafts or camshafts, milling machines with one or two milling carriages are currently used, and the workpiece to be machined is moved by a single-acting or double-acting steady rest. The grinder is supported at a location as close as possible to the respective machining position, thereby achieving a good grinding condition and corresponding machining accuracy. According to conventional machining methods, the bearing part of the shaft or the like, for example the crank journal and the crank pin of the crankshaft, are subsequently milled successively from one end of the shaft to the other; The newly formed journal is supported during the machining of the next pin. Conventionally, self-centering steady rests have been used to support this journal, by means of which the journal and thus also its support are brought into a centered position and held in that position. Ru. In this way, even if the workpiece warps due to the release of internal stress during machining,
For each machining step, the drying pin is immediately forced to adjust, so that the relative position of the pin with respect to the journal is guaranteed to remain within suitable tolerances. A disadvantage of the known machining methods mentioned above is that the workpiece returns to its warped state after completion, and the removal of this warp can be done either by special straightening steps, which cannot be automated and is therefore very costly. This is possible only with a grinding process that requires an extremely large amount of grinding.

It is therefore an object of the present invention to eliminate the above-mentioned drawbacks and to improve a method of the type mentioned at the outset, so that a special straightening step following milling is not necessary, and an additional grinding step that would still probably be required. An object of the present invention is to provide a method that can significantly reduce the amount of polishing to be done in the grinding process. Furthermore, there is a need to provide a steady rest for a milling machine, with which the above-mentioned milling method can be rationally implemented.

According to the invention, it is possible to tighten the shaft in the position exactly that it actually takes, without centering it in the respective support position, and in this position to tighten the shaft in the position in which it is mounted or similar. The problem was solved by processing and forming the part. Since the shaft is simply tightened in its support and is not adjusted or centered, the completed workpiece is not warped again and the workpiece is It retains its shape.
This means that, after machining, the unsupported bearing is precisely located in the appropriate position relative to the theoretical workpiece axis, since it is similar to the case with a perfectly centered axis. This is because a milling operation is applied to the bearing in question by means of a tool, with the result that any warping previously occurring due to the released internal stresses is also removed. In addition, as is known, when the journal is supported during milling, and first all the journals are machined and then the crank pin is machined, the final effect is that the journal assumes an eccentric position. It is still necessary to calculate in advance so that the polishing allowance is applied only to the journal. On the other hand, if the journal is supported and not only the crankpin but also the journal is machined, the same situation will occur in this journal as for the crankpin, and by this stage of machining the journal will have been machined. The curvature that had been present is removed, and only a relatively small curvature remains after the shaft is completed. Since no warping action occurs, no other eccentric action is possible,
In the subsequent milling process, it is only necessary to remove the small warping mentioned above, and there can be no difficulty in removing this small warping. Since, according to the method of the invention, there is no ejecting step, it is not necessary that the journal be supported, but a crank pin or a crank arm or the like can likewise be used as the supporting part. Therefore, the support position must be set according to the respective working conditions, and the warpage that still remains after milling the shaft and must be removed;
In addition, it is possible to quantitatively influence the amount of polishing required, and furthermore, it is possible to locally limit it.

The method according to the invention is not tied to a specific milling sequence, but can be applied to all possible forms of crankshaft or camshaft milling, for example by milling each bearing part in stages. When machining, always 1 for stepwise milling of two bearings each.
In each case when two shaft sections are supported simultaneously or simultaneously, when a concentric support is held and when the support is advanced, in the case of milling with preparatory and post-processing machining steps, This is the case, for example, in milling, which has only one finishing step. However, the application of the method according to the invention is almost limited to short shafts, such as crankshafts or camshafts of motors of passenger cars and trucks, since in this method the influence due to the weight of the workpiece is not taken into account at all. First, in the case of a short shaft, this problem regarding dead weight does not occur at all.

Since the method according to the invention supports the shaft without simultaneous centering operations, it is also possible to support unmachined shaft sections, thereby avoiding high costs such as the rotation of steady rest supports or the like. This eliminates the need for additional preparation and operation means. Furthermore, as a result, the arrangement of the support position relative to the processing position can be extremely freely arranged.

The steady rest device has at least two clamping jaws, which can be mounted in their respective supporting positions by means of an adjusting drive independently of one another and are jointly subjected to a pressure load after mounting. In a milling machine for carrying out the method according to the invention of the type described above, each clamping jaw of the steady rest device is individually and mutually independently controlled by the clamping device assigned to it. The present invention proposes a milling machine for machining a crankshaft or a camshaft, which can be fixed and tightened in any desired position. Since the crankshaft or camshaft must be tightened without being centered, each tightening jaw must be able to be installed independently, and the required tightening pressure is such that all the clamping jaws are in contact with the workpiece. It is activated only after the

On the other hand, it allows free movement of the tightening jaw,
On the other hand, hydraulic or pneumatic drives are especially suitable as adjusting drives which make it possible to apply a common tightening effect to the respective clamping jaws after they have been installed on the workpiece; or to a common pressure medium supply, which makes it possible to effect the desired adjustment effect on the hydraulic or pneumatic drive without significant construction outlay. In this case, if a tightening device for the tightening jaw is also used, it becomes extremely easy to support the tightening jaw, which has been appropriately loaded and adjusted by the adjustment drive, to be fixed in its predetermined support position. The desired shaft machining takes place with the adjusting drive described above being unloaded.

In order to be able to apply the method according to the invention even in cases where the workpiece is rotated during milling, the clamping jaw, together with its adjusting drive and clamping device, is rotatably supported around the workpiece. Advantageously, it is attached to a ring-shaped holder with a ring-shaped structure. This allows the shaft to be eccentrically tightened in its support position if necessary;
Moreover, the annular holder allows the clamping jaw to rotate together with the workpiece, so that despite this eccentric support the shaft can be rotated for milling its bearing. In this case, if it is possible to select whether or not the ring-shaped holder is to be fixed in position, the steady rest device can of course be used for milling both stationary and driven shafts. .

The invention will now be explained with reference to the illustrated embodiment.

Steady rest device 2, 2 movable longitudinally over the machine bed 1 of a milling machine (not shown in detail)
a is equipped with three adjustable clamping jaws 3, 3a, one hydraulic drive 4, 4 in each case for adjusting the clamping jaws 3, 3a.
a is used. This hydraulic drive device 4, 4
a are connected to each other via conduits 5, 5a and are jointly supplied with pressure medium. Hydraulically or mechanically driven clamping devices 6, 6a are provided for fixing the individual clamping jaws 3, 3a in a desired position.

In milling machines for machining stationary workpieces, the clamping jaw 3 is mounted directly in a guide member 7 fixed to a steady rest and can be easily adjusted in radial position via a hydraulic drive 4. (shown in the right half in Figure 1 and in the lower half in Figure 2).
In addition, in a milling machine for machining a rotating workpiece, the tightening jaw 3a needs to be able to synchronize with the movement of the workpiece (shown in the left half in Figure 1 and in the upper half in Figure 2). .
In order to meet this need, the tightening jaw 3a is integrated with its hydraulic drive 4a and tightening device 6a.
It is attached to one ring-shaped holder 8 and is arranged in a guide member 9 which is fixed thereto and is radially adjustable. A ring-shaped holder 8 surrounds the workpiece to be machined and is rotatably mounted in the steady rest 2a. In this case, the drive of the holding body 8 is synchronized by the transmission 10 with the rotation of the workpiece, so that during machining of the workpiece its support part is rotated in relation to the workpiece. For supplying the hydraulic drive 4a, a conduit 5a opens into an annular conduit 11 of the annular holder 8, which is in a manner not shown in the drawings.
It is connected via a rotary outlet guide to a pressure medium supply installed in the ring-shaped holder or to a pressure medium supply arranged outside the holder.

Because the steady rest devices 2, 2a are equipped with suitably adjustable clamping jaws 3, 3a, it is possible to clamp the workpiece 12 without having to center it, so that the workpiece 12 may be fixed at an eccentric position. As a result, when milling a crankshaft or the like, it is possible to support the shaft in its actual position and prevent the crankshaft from warping again after completion. It can come off.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which the left half of FIG. 1 shows a steady rest device for machining a rotating workpiece, and the right half shows a steady rest device for machining a stationary workpiece. FIG. 2 is an axial sectional view of both embodiments taken along the line - in FIG. 1. 1... Machine bed, 2, 2a... Steady rest device, 3, 3a... Tightening jaw, 4, 4a... Hydraulic drive device, 5, 5a... Conduit, 6, 6a...
Tightening device, 7, 9... Guide member, 8... Ring-shaped holder, 10... Transmission device, 11... Ring-shaped conduit, 12... Workpiece.

Claims (1)

[Claims] 1. A method for milling a crankshaft or a camshaft, the workpiece being clamped at both ends thereof, and the workpiece being machined to form a bearing or similar part of the shaft. of the type in which the shaft is supported in at least one place, the shaft is tightened in the position exactly in which it is actually taken, without centering the shaft in the respective support position, and in this position the bearing part of said shaft is tightened. A method for milling a crankshaft or a camshaft, characterized in that it involves machining or forming similar parts. 2. The milling method according to claim 1, wherein the shaft is fixed in the existing position by supporting at least one of the journals the shaft has. 3 Milling machines that clamp the workpiece at both ends for milling crankshafts or camshafts and support the workpiece in at least one place during the machining and forming of bearings or similar parts of the shaft; The steady rest device for the milling machine has at least two clamping jaws which can be applied individually to each support point by means of a hydraulic or pneumatic adjusting drive, irrespective of their relative position. In the case of a type that can be attached and is commonly pressurized after being applied, each tightening jaw 3, 3a of the steady rest device 2, 2a belongs to the tightening jaw 3, 3a. A milling machine for machining a crankshaft or a camshaft, which is capable of fixing and tightening each of them at any arbitrary position individually and independently of each other by means of tightening devices 6 and 6a. 4. The tightening jaw 3a of the steady rest device 2a, together with its hydraulic drive device 4a and tightening device 6a,
4. The milling machine according to claim 3, wherein the milling machine is mounted on a ring-shaped holder (8) which surrounds the workpiece (12) and is rotatably supported.