The present invention relates to a manufacturing method for curved and quenched profile elements from closed profile elements, beams, or similar according to the mgressing part of claim 1 and a die tool to perform the method

Since a long time it is already known to form and quench workpieces out of steel Usually this is effected in that the workpiece is provided with the desired form by means of chosmg suitable operations and suitable tools, whereafter it is heated to the quenching temperature and is to avoid form changes duπng the quenching process placed into a separate fixture, in which it is cooled down with a convenient speed depending on the chemical composition of the steel. Besides the unnecessarily large tool costs for two separate tools the πsque for the formation of an oxide scale increases as the profile element in its heated state must be processed between these tools or fixtures

Since a long time there existed the desire to make the production of quenched and formed products simpler and cheaper by means of both forming and quenching the product in the same tool. Thus it had especially shown to be difficult to design the press and quenching tools in a suitable way to achieve the high cooling speed, which especially for a quenching low alloy steel is totally determining to achieve a good quenching result.

As to what is already known in the art it is referred to that it is known to achieve highly resistant plate elements by means of a so-called press quenching in one and the same tool by means of of a simultaneous forming and quenching In this method one proceeds from a low alloy plate shape to be heated to the quenching temperature, usually 800 to 950 centigradcs, whereafter the shape is placed m a pressing tool provided with cooling channels and is formed while being quickly quenched by means of a cooling medium flowing in the channels. This method, however, is only adaptable for generally plane surface-like plate elements with large heat distributing surfaces and not for the present invention with closed profile elements with comparatively small heat distributing surfaces

From US-4,057,230 and US-3,589,697 methods and devices are already known to quench bearing sites of crank shafts For the fixation of crank shafts heated to the quenching temperature a sort of devices is used comprising first parts arranged at a relative distance and relatively flexible and provided with several protruding second parts, on the free ends of which recesses are provided with the object to receive and essentially circumsize the crank shaft beaπng sites, when the flexible first parts aTe brought together The quenching of the crank shaft beaπng sites is performed b\ means of several channels running through the

protruding parts, the channels debouching at the periphery of said recesses for supplying and removing a cooling liquid.

Especially in the car industry there has been a demand since a long time to be able to produce curved, quenched profile elements in a simple and cheap way and from low alloy steel plate, such as posts and roof profiles to replace highly resistant material hitherto being used in the vehicle body supporting parts without renouncing the safety and the weight reduction which is always desirable, not at least for environmental reasons today.

Therefore, the object of the present invention is to simplify and to cheapen the manufacturing of closed curved and quenched profile elements in providing a new and improved manufacturing method and a die tool to perform the method. The invention provides more in detail to manufacture closed curved and quenched profile elements in one common tool for both the curving and the quenching. The manufacture of closed curved and quenched profile elements can in this way also easily be integrated into a generally existing manufacturing line for the continuous production of straight quenched closed steel profiles.

This object of the invention is achieved by means of the characteristic features stated in the characterizing part of claim 1 and 2.

In providing a quenching method and a die tool with the cooling liquid supplied to the die tool with the therein contained and curved profile element and in that the cooling liquid is guided through the die tool for heat dissipation and thus making possible to manufacture with only one tool on the outside of the therein contained profile clement in a conventional manufacturing line of a type which is normally and generally provided to manufacture straight quenched closed profile elements.

The invention will be described here below in connection with an embodiment with reference to the attached drawings, where

Figures 1 to 3 are perspective views of a part of a manufacturing line during the various steps of the manufacture of closed curved and quenched profile elements according to the method of the invention and a die tool for their manufacture, and

Figure 4 shows a side view of another embodiment of the die tool in figures 1 to 3.

With reference to figures 1 to 3 a quenching station is generally referred to as 1, comprised as a part at the end of a manufacturing line to manufacture closed curved and quenched profile elements 2 according to the invention. In the figures a portion of the path 3

is shown provided with driving rolls 4 to transport the profile elements on along the path. The quenching station comprises a die tool 5 to curve the profile elements and a cooling device 6 for the curved profile elements. The cooling device 6 comprises a showering or flushing device 7 freely supplying cooling liquid and steadily supported by means of a bracket in form of a beam 8 or similar running over the path 3.

The arriving profile element 2 in figure 1 is heated to the quenching temperature in a previous here not shown step. The heated profile element 2 is by means of the driving rolls 4 transported to the die tool 5 comprising two against each other movable tool halves 9, 9' for forming or curving the profile element 2, the insides of the halves provided with such a form thata profile element placed between them is provided with the desired curvature when driving the tool halves 9, 9' towards each other. To be movable along the path 3 and thereby movable to-and-fro for passing under the flushing devices 7 the tool halves are supported by means of a corresponding portal construction 10,10' guided along a guide block 11, 11' or similar running on each side of the path 3. A simultaneous reciprocating driving of said portal construction 10 and 10', respectively, is performed by means of some suitable, here not shown mecanism of an already known type, e.g. by means of a nutscrew type. In the same way the driving of the tool halves 9, 9' towards each other is performed, i.e. to curve the there inbetween placed profile element 2, by means of some suitable mecanism, e.g. by means of hydraulically operating cylinders 12 shown in the figures.

Each tool half 9, 9' is on its inside provided with reverse alternating cicrcumferential fingerlike ribs 13 and grooves 14 running continuously along said insides. The object of these ribs and grooves is to let the from the showering or flushing device 7 freely exiting cooling liquid pass the die tool 5 to dissipate the heat from the outside of the profile element 2, inspite of being all the time encased in the die tool 5. For this purpose the direction of the grooves formed on the corresponding insides of the tool halves is choosen in such a way that they run parallel to the flushing direction. With the profile element 2 encased in the die tool 5 these grooves will form channels debouching in the direction towards the showering or flushing device 7. On its way through the channels the cooling liquid passes on the outside of the encased profile element 2 and thereby dissipates heat from it.

Figures 2 to 3 show, how the die tool together with the there encased and curved profile element 2 is transported through the showering or flushing device 7. When the die tool 5 passes the flushing device 7 and the profile element 2 finally is quenched, the tool halves are

separated to release the profile element. The die tool 5 may then return to its original position to be ready for the next heated profile element 2.

Figure 4 shows another embodiment of the die tool 5 for performing the method of the invention. In this embodiment the die tool is especially provided for curving and quenching of profile elements 2 formed unsymmetrically in cross section and thus for the manufacture of so-called double curved profile elements. For this object the free edge portions 15 of the protruding fingerlike ribs 13 are provided with recesses 16 with a profile generally corresponding to the cross section profile of the profile elements, the profile element 2 encased in the die tool being in an advantageous way supported during the curving and quenching.

It is evident that the embodiment of the invention described above and illustrated in the figures has been chosen for a better clearness to be described in its simplest form. It is of course within the scope of the invention also possible to adapt the die tool to form curved and quenched profile elements being esentially more complicated than the profile elements described above. Thus it is e.g. possible to provide the recesses 16 with such a profile that the encased profile element is not only curved in a horisontal plane, as shown in the figures, but also in a plane perpendicular to the horisontal plane. Thus, starting from a straight profile element, it is possible to achieve with the same die tool a quenched profile element with an irregular curving, such as posts and roof profiles incoφorated in a vehicle body.

The method and the die tool of the present invention make it possible to use one common tool both to curve and to quench for manufacturing closed quenched and curved profile elements. Besides the tool costs to be spared in this way also the heating period of the heated profile element is reduced and thus the risque for the formation of an oxide scale. Moreover it is with the same production line and with a varying production sequence possible to manufacture both straight and curved closed and quenched profile elements.

The present invention is not limited to what has been described above and has been illustrated in the drawings, but can be altered and modified in many different wayswithin the scope of the inventive idea specified in the claims. Even if illustrated in the drawings the ribs and recesses have not to be situated at an equal relative distance, but the distance them between can of course be varied. Moreover, it is possible to arrange showering or flushing nozzles between the ribs, i.e. in the recesses, by placeing the cooling liquid channels in the tool halves.