Electric Upsetting Machine

Abstract

An electric upsetting machine comprising an upsetting device, a pair of clamping electrodes, an anvil electrode and a transformer, the clamping electrodes being arranged in at least two adjacent pairs arranged to operate in parallel.

Description

The invention relates to an electric upsetting machine comprising an upsetting device, a pair of clamping electrodes, an anvil electrode and a transformer. The pair of clamping electrodes, also called guide electrodes, serve to guide a workpiece which is upset against the anvil electrode by the upsetting device.

A known machine of this type is provided with a single guide electrode and a single transformer and this guide electrode is constructed as a mechanical sleeve which encloses the workpiece to be upset. The disadvantage here is that this machine can only press one workpiece at a time and the machine can always only be arranged in such a way that only workpieces of a certain range of thickness can be worked.

It is the object of the invention to provide a machine of the previously mentioned kind, whose operational possibilities are greater than those of the known electric upsetting machines.

This invention provides an electrical upsetting machine comprising an upsetting device at least two pairs of adjacent clamping electrodes operable in parallel and electrically insulated from one another, anvil electrode, and a transformer for each pair of clamping electrodes, said transformers being arranged so that each transformer is electrically connected to only one of the pairs of clamping electrodes and all the transformers are electrically connected with the anvil electrode.

This apparatus is thus an electric upsetting machine having various operational possibilities.

Two or more than two workpieces can be worked upon simultaneously with a machine according to the invention. The workpieces can be transported by means of parallel displacement between two clamping electrodes and can be transported from one pair of clamping electrodes to the next, without being displaced in the direction of their lengths. In this process, the current flow through each of the workpieces arising between the pair of clamping electrodes and the anvil electrode is independent from the current flow through the other workpieces.

It is preferable that each clamping electrode of each pair of clamping electrodes is respectively connected through a circuit to a guide electrode conductor of the corresponding transformer. In this way, an improvement of the current flowing from the clamping electrodes to the workpieces is attained. Further increase of operational possibilities of the machine is attained if a clamping jaw, respectively electrically interconnecting the two clamping electrodes, is removably secured to the adjacent clamping electrodes of at least two pairs of clamping electrodes. In this construction one workpiece can be operated upon by using the power of two transformers. Conveniently, corresponding to the number of guide electrodes, there are provided at least two upsetting cylinders and the pressure rise in each of these cylinders causes release of a switching process which is related to the lengths of the workpieces acted upon by the cylinders. In this way workpieces of different initial lengths can be upset independently from one another.

The drawings illustrate a preferred embodiment and show in:

FIGS. 1a and 1b a side view of an electric upsetting machine,

FIGS. 2a and 2b a section on the line II--II in FIG. 1,

FIG. 3 a section on the line III--III in FIG. 1.

Two clamp slides 1, 2 are arranged one above the other on the machine shown in FIGS. 1 to 3. The upper clamp slide 1 is movable up and down between two guides 3 and the lower clamp slide 2 is similarly movable up and down between two guides 4. Arranged below the lower clamp slide 2 is a clamping cylinder 5, whose piston rod engages the lower clamp slide. The piston rod of a clamping cylinder 6, arranged above the upper clamp slide 1, likewise engages the upper clamp slide 1. The two clamp slides 1, 2 respectively carry, at their facing sides, two pairs of clamping electrodes 7 and 8, the electrodes of each pair being horizontally adjacent and insulated from one another by an insulating layer 56. A clamping jaw 9 is arranged on each of the two upper clamping electrodes 7, and each of the lower clamping electrodes also carries a clamping jaw 10. Each of the two pairs of clamping jaws 9, 10 carries a workpiece 11, 12 in the shape of a rod shaped blank. Each workpiece 11, 12, while it remains a blank, projects from the clamping jaws 9, 10 on one side as a short section, and on the other side as a long section.

Co-axially arranged with respect to each pair of clamping jaws 9, 10 is a die 13, 14. The two dies 13, 14 are almost adjacent and are both partially fitted into an anvil electrode 15 which is cup-shaped and which takes the place of several individual anvil electrodes, and is fitted on a vertically arranged contact plate 16. Respectively arranged above and below the anvil electrode are contact pieces 17. Provided on the side of the said contact plate 16, which is presented away from the anvil electrode 15, are two further adjacent contact plates 18 parallel to the said contact plate 16. Provided behind these contact plates 18 is an abutment 19 of an anvil slide 20 which carries the previously mentioned parts and is displaceable in a horizontal direction. A support 21 is arranged on the anvil slide 20. This is spaced from the abutment. Spaced behind the anvil slide 20 is a further cylinder 22 which carries an extension 23 on its upper forward end. A spindle 24 passes through the extension 23 and the support 21, and carries respective nuts 25 on both sides of the extension 23 and the support 21. This arrangement thus secures the spindle 24 in a releasable manner. The further piston, which projects from the cylinder 22, carries a block 26 having frontally arranged two parallel upsetting mandrels 27, 28 which project through the support 21, the abutment 19, the contact plate 16 and the contact plates 18, and into the two dies 13, 14.

Arranged in front of the long sections of the workpieces 11, 12 is a casing 29 in which are housed two upsetting cylinders (not shown) of an upsetting device. The piston rod of an upsetting piston 30 projects backwardly from each cylinder carrying an upwardly directed bar 31 on its projecting end. An extension 32 is provided on the casing 29 for each of these pistons 30. A spindle 33 projecting through each extension 32 is connected to the bar 31 and carries a nut 34 between the extension 32 and the bar 31. Each upsetting piston 30 being hollow at its projecting end, contains a movable threaded spindle 35, which projects backwardly and carries a nut 36 which is supported opposite the associated piston 30.

A fixed transformer 37, 38 is respectively provided above and below the anvil slide 20, each having two electric conductors 39, 40, one of which leads to the contact plate 16 and the other to the further contact plate 18. The conductors 39, 40 of the upper transformer 37 are arranged on top of the contact plates 16, 18 and the conductors of the lower transformer 38 on the bottom. The rear contact plates 18 are connected to the four contact pieces 17 by means of four contact bolts 56 projecting through the front contact plate 16, whereby two contact bolts 56 and two contact pieces 17 are respectively provided at the top and at the bottom. An electric conductor 41 leads from each contact piece 17 to one of the four clamping electrodes 7, 8 whereby two of these conductors 41 pass above the dies 13, 14 and the other two pass below the dies. The conductors 39, 40, 41 are flexible.

The two contact plates 18, the four contact bolts 56 and the contact pieces 17 are electrically interconnected, but from the remainder of the apparatus are insulated. There is thus a current loop for the upper transformer 37. This current loop runs from one conductor 40 and over one of the two contact plates 18 and is divided there, so that it runs through the upper contact bolt 56, upper contact piece 17, upper clamping electrode 7 and upper clamping jaw 9, it also runs through the lower contact bolt 56, lower contact piece 17, lower clamping electrode 8 and lower clamping jaw 10 to the workpiece 11. The current loop is completed through the workpiece 11, the die 14 or anvil electrode 15, contact plate 16 and conductor 39. There is a similar current loop for the transformer 38, whereby the current supply runs through the workpiece 12.

A frame is provided comprising two front columns 42, two center columns 43 and two back columns (not shown). The columns carry two spaced, parallel slideways 45. On their inwardly facing sides the two slideways 45 have guide tracks, on which a plate 46 is located, the plate 46 carrying the casing 29 and being secured to the slideways. A plate 47 engaged on the rear of the guide tracks is also secured thereto and carries the further cylinder 22. Furthermore, the anvile slide 20 is movable and is secured against vertical removal by means of a cover strip 49.

The lower transformer 38 is mounted upon a support 50 which rests on the ground. The upper transformer 37 is attached to the support 51 and is further supported from two diagonal trusses 52, each of which connects a center column 43 and a rear column. Arranged between the front columns 42 and the center columns 43 is a sub-frame 53 whose lower cross beam is engaged by the lower clamping cylinder 5. Each of the center columns 43 carries above it a support arm 44. Fixed to this support arm is a sub-frame 55 whose upper cross-beam is engaged by the upper clamping cylinder 6. The two sub-frames 53, 55 carry the respective guides 3, 4. The clamping slides 1, 2 are movable in the guide-tracks of the respective guides 3, 4 and are held by means of strips 54. Support arms may alternatively be employed to permit free lateral access to the clamping electrodes.

The electric upsetting machine according to the invention can heat up and form rod shaped workpieces in a wide area of different cross-sectional sizes with maximum economy. In this process two rods are simultaneously heated up and formed in the lower part of the work zone while in the upper part of this zone only one rod may be heated up and formed. Furthermore, complex head shapes can be produced and rod material of a smaller size can be used. More complex head shapes can be produced in two stages. The blank can be partially pre-heated during the first stage. With the aid of a current control device controlling the circuit, the heating-up speed during the parallel upsetting of two rods can be controlled independently and the workpiece can be transported horizontally through the machine without lifting or longitudinal displacement. It has also been taken into consideration that a predetermined heating-up and forming speed cannot be exceeded if perfect head shapes are required and if the quality of the material is not to be impaired. The limits are visible, for instance by two great a current density at the contact surfaces of the clamping jaws, and sometimes also at the anvil plate. Since the system for controlling the current according to the invention assures equal current flow into both workpieces, it is possible simultaneously to heat up and form two blanks. It is known that electric current flows through a member of lowest resistance, that is to say, that more current would flow through the workpiece having the lowest electrical resistance and would thus be heated up more quickly than the other. Apart from the specific resistance of the workpiece there are a number of other factors which could act in this sense, for example, the effect of the electric field which is also influenced by the current control.

The method of manufacturing workpieces in which the cross-sections change lengthwise described in the German Pat. No. 1,268,941 can be improved according to the invention in such a way that the section with the smaller cross-section is produced in the first die, and that the section having the greater cross-section is produced in the second die. In the method of the above patent, two die sleeves are arranged within one another. The smaller one is displaced during the pressing of the section having the smaller cross-section and thus slides in the outer sleeve. This tool construction has the disadvantage that the inner sleeve cannot be cooled adequately and is therefore subject to relatively high abrasion. This can be essentially simplified in the above described two stage method, by using a simpler cylindrical anvil plate as the small head, instead of using a relatively thinner anvil sleeve. For this it is necessary that the two dies are immediately adjacent in order to enable fast transfer to take place and to avoid heat loss in the section already formed. This is not possible with joined individual units, since the distance from die to die is inevitably greater.

Secondly it is necessary that the electric current to the zones of the rod to be heated can be independently controlled and adjusted without electrically insulating the dies or anvil tools against one another. Thus, the two dies or anvil tools can be arranged immediately adjacent to one another and the operations in the two dies can be carried out completely independently.

By the arrangement of the current control according to the invention, it is possible to connect the clamping electrodes co-axially with the workpiece blank to the transformer by partially flexible straps, This solution has the advantage that the rod can be transported in a horizintally controlled orientation. Moreover, the progress of the rod can be carried out optionally from the left to the right or vice versa. Moreover, this structure provides all round access to the tools and to other functional parts. Sometimes two rods can be of different lengths while being simultaneously formed. The machine is therefore equipped with a special device which balances the difference in lengths before the start of an upsetting process and so that both rod ends have pressure applied to them at the anvil electrode at the beginning of the operation and that the same volume of material is deformed on each of the rods.

Two independently operating upsetting cylinders are provided to enable two different operations to be carried out simultaneously, for instance during the upsetting of parts with cross-sections which may vary lengthwise of the parts.

The electric upsetting machine according to the invention can have several operational variations, that is, simultaneous die upsetting of two rods, simultaneous free upsetting of two rods, die upsetting of one rod and free upsetting of one rod. The change-over from die upsetting with two workpieces to free upsetting with two workpieces takes place as follows: An anvil plate is fixed in front of each die. The further cylinder is tightly connected to the anvil slide and the lock of the anvil slide is released. Subsequently, the upsetting stroke and the anvil stroke are corrected, the pressure for upsetting and the electric current power are adjusted and the machine is ready to operate. The change-over from upsetting of two workpieces to upsetting of one workpiece to free upsetting takes place in such a way that the two anvil plates in front of the dies are replaced by a centrally arranged plate. The two pairs of clamping jaws are removed and replaced by a bigger pair of clamping jaws, the latter being inserted in the center of the two clamping electrodes and both are electrically connected.

The following describes a heating up and forming process. Two rod blanks are inserted for instance into the lower clamping jaws of the machine which is ready for work. The machine is switched on by a foot or hand switch, the upper clamp slide comprising the clamping electrode and then slides downwards, and after that the lower clamping slide comprising the clamping electrodes slides upwards. By this means the rods are secured into the clamping jaws. The anvil slide, which occupies its right hand position is tightly locked during the die upsetting process. The further cylinder of the machine is always, when the machine is rendered operational, in the right hand position. After the rods are secured radially, the upsetting cylinders move in the direction of the clamping electrodes and now also secure the rods between the anvil and the upsetting cylinder in a longitudinal direction. If two independently operating upsetting cylinders are provided the length variations between the two blanks are balanced by moving the positions of the cylinders. As a result of securing of the rods, the pressure in the upsetting cylinders rises and thereby automatically operates a hydraulic pressure switch which connects the heating current and thus initiates the process. During the heating up and forming, the further cylinder with the mandrels, withdraws and the upsetting cylinders press axially with constant force onto the rods and effect the forming. During this process, each of the two upsetting cylinders runs through a predetermined stroke. As soon as one of the two cylinders has reached the final position, the heating current of the rod concerned is switched off. As soon as both cylinders have reached their final positions, the clamping jaws open and the upsetting cylinders travel back to their original positions. Afterwards, the further cylinder also travels back into the starting position and thereby ejects the working pieces through the mandrels. The working pieces can now be removed from the machine.

Claims

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An electric upsetting machine comprising an upsetting device a pair of clamping electrodes, an anvil electrode and a transformer, characterized in that at least two pairs of adjacent clamping electrodes are provided which operate in parallel.

2. An electrical upsetting machine comprising an upsetting device, at least two pairs of adjacent clamping electrodes operable in parallel and electrically insulated from one another, an anvil electrode, and a transformer for each pair of clamping electrodes, each said transformer is electrically connected to only one of the pairs of clamping electrodes and all the transformers are electrically connected with the anvil electrode.

3. A machine according to claim 2, wherein a first contact plate is attached to the anvil electrode, at least two further contact plates, each electrically connected with one of the transformers, are provided on one side of the first contact plate, contact pieces are provided on the other side of the first contact plate and are connected by electrical conductors with respective pairs of clamping electrodes, and contact bolts on the further contact plates extend through the first contact plate and are attached to the respective contact pieces so that one of the further contact plates is connected with each pair of clamping electrodes.

4. A machine according to claim 2, wherein the anvil electrode is cup-shaped and is arranged to receive at least two dies.

5. A machine according to claim 2 wherein two pairs of clamping electrodes and two transformers are provided, one of the two transformers being arranged above and the other transformer being arranged below the two pairs of clamping electrodes.

6. A machine according to claim 2, wherein a cylinder is provided, said cylinder having a piston provided with at least two upsetting mandrels.

7. A machine according to claim 6 wherein the anvil electrode is arranged on a movable anvil slide which can be fixed at varying distances from the cylinder, the said piston is connected to an anvil slide, and the anvil electrode is mounted for movement with the anvil slide.

8. A machine according to claim 2, wherein an upsetting cylinder is provided for each pair of clamping electrodes, the pressure rise in each of these upsetting cylinders being arranged to cause operation of a switching process which is related to the length of a workpiece acted upon by the said cylinder.

9. A machine according to claim 8 characterized in that each of the upsetting cylinders is provided with a hydraulic pressure switch which energizes the current circuit of one of the transformers.

10. A machine according to claim 8, wherein each of the upsetting cylinders has a stroke adjusting device in which a threaded spindle can be secured into a piston of the upsetting cylinder and can be secured thereto by means of a nut.

11. A machine according to claim 8, wherein each of the upsetting cylinders has a stroke adjusting device in which a bar, which is fixed to a piston of the upsetting cylinder, carries a spindle having a nut which is secured to a relatively fixed extension opposite to the upsetting cylinder.

12. A machine according to claim 2, wherein two horizontally adjacent clamping electrodes are arranged for vertical movement in a common slide.

13. A machine according to claim 12 characterized in that a clamping cylinder which moves the upper clamping electrode of the pairs of clamping electrodes in a vertical direction, is fixed to a support arm on a column.

14. A machine according to claim 2, constructed so as to be capable of operation as a die upsetting machine.

15. A machine according to claim 2, constructed so as to be capable of operation as a free upsetting machine.