EP1434661B1 - Method for loading internal high pressure forming presses and device therefor - Google Patents

Abstract

The invention concerns a method whereby components are arranged in a mounting device, outside an internal high-pressure forming press, in accordance with their position and their function, such that they are linked to one another. The mounting device comprises an upper part and a lower part including cavities identical to the cavities of the internal high pressure tool. Once the components have been installed, the mounting device is introduced in the internal high-pressure press, then the upper part or the lower part of the mounting device is withdrawn, the part of the mounting device remaining in the internal high-pressure press being displaced against the upper tool or the lower tool. For the forming process, the components are maintained in a part of the tool by depression or by clamping, then the part of the mounting device is removed from the internal high-pressure press, thereby ensuring high precision positioning of components. Additionally, the production rate is substantially increased. The invention is particularly applicable for the production of cam shafts.

Description

The invention relates to a method for feeding hydroforming presses (hydroforming presses) in order to produce workpieces which are composed of several parts, preferably camshafts, in a hydroforming process known per se, and a device for carrying out the method. Through the hydroforming process, cam rings and also other components, such as drive elements, are connected to one another in a force-locking and form-fitting manner. The hydroforming press carrying out the method is adapted to receive at least one workpiece, i. a camshaft, which consists of a hollow shaft with the cam rings to be applied thereto equipped.

The hydroforming process generally changes workpieces that are hollow by the effect of a pressurized medium (air, liquid) in their geometry and dimensions. These axial forces deform the workpiece as far as it goes through the mold; Also called Formnest, is to specify in the IHU press.
Such hydroforming presses have two tools, a lower tool and an upper tool whose mold cavities correspond in the closed state of the shape of the entire workpiece, the camshaft with the functionally arranged cam rings. In general, the separation of the workpiece takes place in the middle.

There are various designs of hydroforming presses or their tools are known, but all work on one principle. The workpieces to be treated are inserted and the internal pressure deforms them. It is preferred to produce rotationally symmetrical workpieces. The process itself, the pressing process, runs in extremely short time, but the non-productive time, especially the loading of the hydroforming press takes a long time, so that the cycle time is ultimately long.
An attempt has already been made to produce camshafts from a hollow shaft and cam rings mounted thereon. Here, the time of placement is very long, because the cam rings must be very accurate in their position, ie their subsequent function accordingly, inserted and must not be changed by the vibration and vibration of the hydroforming press in their position (angular position). In addition, the position of some cam rings, due to their shape, is very unstable, and it is precisely these that are at risk of change in position. If the correct functionally correct position of the cam rings is also checked with gauges or other test equipment after insertion into the hydroforming press, a change in position can not be ruled out when closing the tool. A change in position only one cam ring has significant consequences. The cam rings are hardened and destroy the tool in the wrong place in the mold cavity and are also damaged and unusable. Since the tools are very expensive, such damage must be ruled out. As efforts are made to increase the productivity of hydroforming processes, the tools are also designed to accommodate multiple workpieces. Of course, there are also limits, because the supply and control of the pressure medium causes associated further measures and increased effort, which in turn increases the cost of the hydroforming press and ultimately the process costs.
These disadvantages do not occur when forming simple rotationally symmetrical workpieces to the extent, but in such complicated workpieces as camshafts, which require a very high precision due to the function. Slight changes in position of cam rings Gravity alone, which has a particularly critical effect in connection with machine vibrations when the cam rings with the cam tip are upwards and at an angle deviating from the vertical, must be ruled out; and this is hardly possible with the known methods of feeding the hydroforming press.

The DE 36 43 803 A1 discloses a built-in camshaft mounting apparatus and method of assembly. Disclosed is a mounting device for built camshafts with a holding device for axial fixing of individual elements such as cams, bearing seats or gears and a pressure medium probe for hydraulic expansion of a hollow shaft in sections in which the elements and the hollow shaft are non-positively connected. In this case, individual fixing discs are provided for the holding device, each having a central opening for receiving one of the elements such as cams, bearing seats or gears and an outer bearing seat for receiving in each case a bearing point of the holding device. About this Fixierscheiben the individual elements can be fixed angularly before assembly, wherein the hollow shaft can perform radial movements relative to these. This known assembly device thus comprises a lower part and an upper part, wherein in the lower part and upper part identical mold cavity for receiving parts introduced and lower part and upper part are accurately connected. Here are in the upper part and / or lower part at the points where a position assurance of the parts is required, positioning arranged on the upper and lower part, which ensure a perfect fit connecting these parts together.

The above cited publication further discloses a method for assembling a camshaft. In this method, all parts of the camshaft in the lower part of a mounting device, which consists of a lower part and upper part, inserted positionally and functionally; the spatial and functional position of the parts is checked; the upper part of the mounting device is placed on the lower part; by clamping the parts in the mounting device in the predetermined position non-positively and positively connected; the upper part of the mounting device is then deposited with the parts held in it by means of positioning elements in the exactly defined position on the lower tool.

The invention has for its object to provide a method for Bestukken of hydroforming presses, which makes it possible, in a known hydroforming process, a non-rotationally symmetrical workpiece, which is composed of several individual parts, preferably a camshaft, and thereby produce the required high precision with regard to the position of the cam rings. Furthermore, the idle time for loading the hydroforming press should be substantially reduced in order to increase the productivity of the process or of the hydroforming presses. A further increase should also be possible in that the method is designed so that several workpieces can be produced in one cycle. The method is intended to exclude destruction or damage to the workpiece or its parts and the hydroforming press.
The hydroforming press should remain in their basic design and mode of operation and be adapted without substantial cost increase, the process of the invention. The device for carrying out the method should belong to the hydroforming press, ie it should be so functionally connected to the hydroforming press that the entire hydroforming process is more economically feasible. The device should be an indirect part of the hydroforming press and serve directly for the procedure.

According to the invention the object is procedurally according to the features of claim 1 or 2 and the associated device, solved according to the features of claim 4. Advantageous embodiments are described in claims 3 and 5 to 12.

The basic principle of the method is that a part of the entire process, a process step in which one or more workpieces are produced at the same time, is taken out of the hydroforming process, also called tact. The assembly of the shaft with the cam rings to be applied to it, which are to be connected to one another, as a process step upstream of the actual hydroforming process is thus outsourced from the cycle by placing in a mounting device all parts belonging to the complete workpiece in their functional position become. In addition to this positioning, this also includes test procedures adapted to the process and workpiece. Thereafter, the positioned parts, secured against impermissible changes in position in the mounting device, transported in the hydroforming press in the open tool. The two-piece mounting device has the same mold cavity for receiving cams and other components to be mounted as the tool of the hydroforming press.
Attached in the upper part of the mounting device terminals and / or suction ensure that all parts (hollow shaft, cam rings, drive elements) are fixed. The upper part is placed on the lower tool of the hydroforming press by means of positioning elements. As a result, in turn, all parts of the mold cavities of the upper part the mounting device and lower tool of the hydroforming press positionally fixed and enclosed. Thereafter, the terminals are released and / or the suction pressure is reduced and pushed the upper part of the mounting device; and the top is removed from the hydroforming press. Now, the upper tool of the hydroforming press is put on, ie the hydroforming press is closed and the actual hydroforming process takes place. In the meantime, additional mounting devices are equipped by an independent history, so that runs in a very short time a clock.
When inserting the parts in the mounting device all control functions and fuses are carried out, so that when introduced into the hydroforming press no or only very insignificant checks of the position of the parts must be made, because they are transported protected against changes in position.

A further solution of the problem is that the parts or assemblies are also held by inserting and fixing in the mounting device in the lower part of the mounting device by clamping and / or suction. The assembly device is transported into the opened hydroforming press and positioned under the upper tool of the hydroforming press. The top of the mounting device is removed and moved out of the hydroforming press. The lower part of the mounting device with the parts held therein is lifted to the upper tool of the hydroforming press and by means of clamping and / or by suction, the parts are now kept functional in the upper tool of the hydroforming press. Thereafter, the connection of the parts is released from the lower part of the mounting device, and it is moved out of the hydroforming press. The further procedure then takes place as in the former method variant.

In order to ensure the high accuracy in the production of the camshaft with respect to the position of the cam rings on the shaft, it is advantageous to perform a check of the position of all parts before closing the hydroforming press.
The suction of the parts in the assembly unit and also in the hydroforming die is carried out by a commercial vacuum pump, which generates a vacuum corresponding to the weight of the sucking parts.

The inventive method has its greatest advantage in that the entire assembly process is eliminated in the hydroforming press except for the retraction of the mounting device. This greatly reduces the cycle time and increases productivity. It can be prepared by the use of multiple assembly facilities large quantities for hydroforming. Furthermore, it is ensured that hardly the parts or the hydroforming tool are damaged by inaccurate insertion or position changes. The mounting device ensures a high process reliability, even when processing multiple workpieces in a tool or a mounting device. The position of the position of the cams in the mounting device by means of known test equipment and method; and a final check before introducing the mounting device takes place in that it is determined when placing the upper part, whether the position of the parts is precise, because otherwise it can not be closed.

The assembly of the mounting device can be done manually or automatically.

The device for carrying out the method is a mounting device that is independently populated outside the hydroforming press and on guide elements in the open hydroforming press is movable. The guide elements are formed not only for transporting the mounting unit in the hydroforming press in and out again, but they also serve the process-accurate attachment of the mounting device to the hydroforming tools. These guide elements are expediently designed so that they take over the entire movement of the mounting device.

The mounting device consists of a lower part and upper part. Both parts have the same mold cavities as the tool lower and upper part of the hydroforming press.

By means of known fitting elements upper and lower part of the mounting device are easily detachably connected to each other. For accurate and immovable positioning of the parts channels are introduced at certain points of the lower and / or upper part of the mounting unit, which are connected via flexible lines with a vacuum generator.
However, it can be arranged at suitable locations for holding the parts and clamping elements, such as brackets on or in the lower and / or upper part, which are easy to open from the outside when the lower or upper part of the mounting device on the lower or upper tool of IHU press would be scheduled.

However, in order to secure the precise mounting of the parts in the hydroforming die, which is particularly necessary when the lower part of the mounting device connected to the upper tool and this is moved out of the hydroforming press, are in this embodiment in the upper tool, in Essentially in the same places as in the upper part of the mounting device, channels introduced, which are also connected to a vacuum generator. In the lower tool The hydroforming press can be used to the usually existing drainage channels.

Fig. 1:

eine Montageeinrichtung im offenen Zustand mit den eingelegten Teilen für eine Nockenwelle im Querschnitt im Bereich eines Nockenringes,

Fig. 2:

eine Montageeinrichtung im Längsschnitt A-A,

Fig. 3:

ein Unterwerkzeug einer IHU-Presse mit darüber befindlichem Oberteil der Montageeinrichtung.

An embodiment of the invention will be described. In the accompanying drawing show:

Fig. 1:

an assembly device in the open state with the inserted parts for a camshaft in cross section in the region of a cam ring,

Fig. 2:

a mounting device in longitudinal section AA,

3:

a lower tool of a hydroforming press with befindlichem upper part of the mounting device.

The mounting device consists of a lower part 1 and a top part 2 and is in Fig. 1 and 2 opened. In this mold cavity 3 are introduced, which are identical to the mold cavities 3 'in a lower tool 4 and upper tool (see Fig. 3 ) of an IHU press. The mounting device is exactly aligned with dowel pins 5, which engage in the holes 6. The mold cavities 3 and 3 'are prepared according to the function-related position and position of the cam rings 7 and the hollow shaft 8. To keep the inserted parts, the hollow shaft 8 and on her the cam rings 7, after insertion in the correct position 7 angular position (especially when the lower part 1 is removed to the assembled upper part 2 on the lower tool 4 of the IHU Press set), channels 9 are provided in the upper part 2 of the mounting device, which are connected via flexible hoses 10 with a vacuum generator. By the negative pressure, the parts are held immobile in their functionally correct position.

For the transport of the mounting device from the mounting place in the hydroforming press guideways are provided, which run in guide grooves. Positioning elements 12 are arranged for the process-oriented connection of the tool to the upper and / or lower part (1, 2).

In Fig. 3 the lower tool 4 is not yet equipped. The upper part 2 of the mounting device is already above the lower tool 4 for lowering this. In the upper part 2, the hollow shaft 8 and the cam rings 7 are held by the negative pressure. The upper part 2 lowers, and by the fitting elements 12, which engage in the holes 6, a precisely fitting guide, ie secured agreement.

The process according to the invention is carried out as follows.
At an assembly site, the cam rings 7 are inserted into the mold cavity 3 in the lower part 1 on the hollow shaft 8. In general, the functional position is ensured exactly by the savings in the mold cavity 3. By means of a suitable testing device, a position control can additionally be carried out. Now, the upper part 2 is guided slowly by the dowel pins 5 in the holes 6 on the lower part. In this case, a further position control is necessarily carried out, because the upper part 2 can be put on only with accurate position of the cam rings 7. In order to exclude a change in position during the following transport of the mounting device in the hydroforming press (also when attaching to the lower tool 4), a negative pressure is generated via channels 9, hoses 10, which sucks the cam rings 7 and the hollow shaft 8 in the upper part 2 and holds , Is the mounting device in the hydroforming press above the lower tool 4, the lower part 1 of the mounting device is lowered and moved out of the hydroforming press. The upper part 2 of the mounting device is lowered by the positioning pins 12 guided on the lower tool 4; the suction pressure is released, and the parts are positioned in the lower tool 4. The upper tool moves down onto the lower tool 4, and the hydroforming process is performed in a known manner. Thereafter, the hydroforming tool opens, and the finished camshaft is removed. In the meantime, the cam rings 7 are mounted on the hollow shaft 8 in a further mounting device, so that they can be retracted into the hydroforming press.

Claims (12)

1. A method for loading several pieces into internal high pressure forming presses, which pieces are to be non-positively and positively connected with each other by the internal high pressure forming process so as to form a workpiece, preferably a camshaft which is assembled from a hollow shaft (8) and cam rings (7), characterized in that

   - each of the pieces of the workpiece are inserted correctly with respect to their position and with respect to their function into the lower part (1) of a mounting device which consists of a lower part (1) and an upper part (2),

   - the correct spatial and functional position of the pieces in the lower part (1) of the mounting device is controlled,

   - the upper part (2) of the mounting device is placed upon the lower part (1), whereby simultaneously a final check is made with respect to the spatially and functionally correct position of the pieces, and wherein the mounting process is finalized only if no deviation is found,

   - the pieces are held in the upper part (2) of the mounting device in the predetermined position by clamping and/or sucking,

   - the thus equipped upper part (2) of the mounting device is moved into the opened internal high pressure forming press between the upper tool and the lower tool (4) or to the lower tool (4),

   - the upper part (2) of the mounting device is placed in the exactly defined position on the lower tool (4) by means of positioning elements (12), wherein the pieces are held in the upper part (2),

   - the pieces are held correctly with respect to position and function in the lower tool (4) by opening the clamps and/or lowering the suction pressure, wherein the lower tool (4) takes over the position securing function,

   - the upper part (2) of the mounting device is transported out of the internal high pressure forming press or is removed from the lower tool (4),

   - the internal high pressure forming tool is closed and the internal high pressure forming process is performed in a manner known per se,

   - the finalized workpiece is removed after termination of the internal high pressure forming process.
2. A method for loading several pieces into internal high pressure forming presses, which pieces are to be non-positively and positively connected with each other by the internal high pressure forming process so as to form a workpiece, preferably a camshaft which is assembled from a hollow shaft (8) and cam rings (7), characterized in that

   - each of the pieces of the workpiece are inserted correctly with respect to their position and with respect to their function into the lower part (1) of a mounting device which consists of a lower part (1) and an upper part (2),

   - the correct spatial and functional position of the pieces in the lower part (1) of the mounting device is controlled,

   - the upper part (2) of the mounting device is placed upon the lower part (1), whereby simultaneously a final check is made with respect to the spatially and functionally correct position of the pieces, and wherein the mounting process is finalized only if no positional deviation is found,

   - the pieces are held in the lower part (1) of the mounting device in the predetermined position by clamping and/or sucking,

   - the thus equipped lower part (1) of the mounting device is moved into the opened internal high pressure forming press between the upper tool and the upper tool (4) or to the upper tool (4),

   - the upper part (2) of the mounting device is lifted off and is removed from the internal high pressure forming press or from the lower tool,

   - the lower part (1) of the mounting device is placed in the exactly defined position against the upper tool, and is closed with the upper tool with precise guidance,

   - the parts in the upper tool are held by means of clamps and/or by means of sucking, and simultaneous therewith the clamps are opened and/or the suction pressure is lowered in the lower part (1) of the mounting device,

   - the lower part (1) of the mounting device is removed from the internal high pressure forming press,

   - the internal high pressure forming tool is closed and the internal high pressure forming process is performed in a manner known per se,

   - the finalized workpiece is removed after termination of the internal high pressure forming process.
3. The method of claim 1 or 2, characterized in that the method step of checking the spatially and functionally correct position of the parts in the lower part or the upper part (1, 2) of the mounting device is dispensed with if the check by placing against the respective counter pieces of the tools can already achieve the checking function.
4. An apparatus for conducting the method according to claim 1 or 2, the apparatus being a mounting device which consists of a lower part (1) and an upper part (2), characterized in that forming cavities (3) are provided in the lower part (1) and in the upper part (2), which forming cavities (3) are identical to those in the lower tool (4) and the upper tool of the internal high pressure forming press for receiving pieces that are to be connected with each other in the internal high pressure forming process,
   in that the lower part (1) and the upper part (2) are connected by means of fitting pins (5) so as to achieve a precise fitting,
   in that channels (9) for holding the pieces are provided in the upper part (2) and/or in the lower part (1), at places where it is necessary to secure the position of the pieces,
   in that the channels (9) are connected to a vacuum pump by means of movable lines (10),
   in that guiding elements are connected to the mounting device such that these guiding elements allow the transport of the mounting device into the internal high pressure forming press between the upper tool and the lower tool (4) as well as the separate transport of the lower part (1) and the upper part (2) out of the internal high pressure forming press,
   and that positioning elements (12) are arranged at the upper part and the lower part (1; 2) and/or at the upper tool and the lower tool (4), which positioning elements allow to connect these parts with each other so as to achieve a precise fitting.
5. The apparatus of claim 4, characterized in that clamps for positioning and holding the pieces are arranged in the lower part and/or the upper part (1; 2) of the mounting device.
6. The apparatus of claims 4 and 5, characterized in that clamps for precisely fittingly holding the parts are arranged in the lower part and/or the upper part (1; 2) of the mounting device.
7. The apparatus of any of claims 4 to 6, characterized in that the fitting elements (5) in the upper part and the lower part (1; 2) of the mounting device are the same elements as used for precisely fittingly connecting with the upper tool and the lower tool (4).
8. The apparatus of any of claims 4 to 7 characterized in that one or more mechanical drives are connected with the mounting device for moving the mounting device into the internal high pressure forming press and to the upper or lower tool (4).
9. The apparatus of claim 8, characterized in that the drives are electrical, mechanical, hydraulic or pneumatic drives.
10. The apparatus of any of claims 4 to 9, characterized in that the mounting device is connected with a known loading device and an associated magazine for the pieces.
11. The apparatus of any of claims 4 to 10, characterized in that channels are provided in the upper tool and/or in the lower tool (4) of the internal high pressure forming press, for holding the pieces when disconnecting the lower part or the upper part (1; 2) of the mounting device.
12. The apparatus of claim 11, characterized in that drainage channels present in the lower tool (4) are used for holding the pieces by sucking.

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