DEVICE IN A PRESS CASTING MACHINE AND METHOD OF USING SUCH DEVICE
In conventional press casting machines the tool halves, which when they are joined together form a mold, are fastened in such a way, that it is very hard and time- consuming to exchange tool halves, which also are called, mold tools. On production-technical grounds press cas¬ ting machines are to be used during long periods of time, which means, that a multishift-use will be the most com¬ mon one. Consequently, presently used tool exchanges sel¬ dom coincide with possible downtime periods, and an ex¬ change must then be done in the middle of a production period. A conventional exchange, which requires an in¬ terference with the interior parts of the machine, im¬ plies first of all a certain cooling period in order to at all allow the personnel to work with the machine without substantial burn injury risks. Said cooling pe¬ riod may be as long as 20-60 minutes, which is a long period of time, during which a large energy consumption takes place in order to keep the metal, which is to be molded, liquid and during which the production is stan¬ ding still. Also without direct burn injury risks ma¬ chine manipulations are difficult and risky, since the available space is very small and thus, injuries easily happen and the operation position often is very inade¬ quate from an ergonomical point of view. An exchange, which is done completely in a manual way, requires usu¬ ally 2-3 hours. Since the operation is done completely in a manual way, human errors may also easily occur. By way of example bolts and nuts, which are not sufficient¬ ly tightened, may result in that a machine part comes loose and castings will be rejected and tools be de¬ stroyed. Also mere service work is subjected, as to con¬ ventional press casting machines, to the above-men-, tioned drawbacks. This may result in that regular ser¬ vice work is neglected and the machine and machine parts
are subjected to an increased wear as well as in that the products will have an inferior quality. In case a strong¬ ly different product category is to be produced instead, the parent tools must also be exchanged, which means pro¬ duction reductions during a period of 6-12 hours, apart from a very demanding and expensive effort in a very exacting working environment.
Known technique is revealed by US-A-4 449 907, US-A-4 529 371, US-A-4 758 147, DE-A-3 220 911, DE-A-3 737 598, EP-A-0 353 59 and JP 58-65 560.
US-A-4 449 907 relates to a device for exchange of tools at a injection machine for plastic material incorporating horison- tally active tools and a vertical parting plane. In this case don't arise same or similar problems as mentioned hereinbefor in connection with vertically active press casting machines for metal. Neither is there any comparable design of machines.
US-A-4 529 371 concerns, like the afore-mentioned publication, a device for exchange of tools at an injection machine for plastic material.
US-A-4 758 147 is a further example of a device for exchange of tools at an injection machine for plastic material.
DE-A-3 220 911 is still a further example of a device for ex¬ change of tools at an injection machine for plastic material.
DE-A-3 737 598 refers also to a horisontally active injection machine and a device for exchange and positioning of tools in connection with such machine. Even here, there are no compara ble problems and solutions to such.
EP-A-0 353 597 concerns a horisontally active injection ma¬ chine with vertical parting plane. Although there are verti¬ cally adjustable supporting plates for the tools as well as an elevator and a turning device, all this equipment is ar¬ ranged outside the machine and without any comparability with the problems of a vertically active press casting machine.
JP 58-65 560 is the only one of these publications to concern a vertically active press casting machine, where tools may pass through the machine, but without lifting of the parent tool or any tool half. These machine parts can consequently not pass any obstacles as other machine parts, e.g. core pul¬ ling devices which extraordinarily limits design and usabili¬ ty of the machine. This conventional machine lacks upper injec¬ tion plunger and provides supply of metal from below. Discharge takes place in the upper mould half and the tool exchange device occupies two sides of the machine. Any tool handling in connec¬ tion with this machine is neither shown nor described.
The object of the present invention is to counteract and as far as possible eliminate the drawbacks mentioned above as well as suggest such features, which will render pos¬ sible fast exchanges of mold tools, whether tool inserts or parent tools having such inserts are used or not. These exchanges are to be done with as few manual efforts as possible or in fact completely or partially automaticly and without consideration of any cooling period. The ob¬ ject of the invention is also to quite generally advance the state of the art in this field and create opportuni¬ ties for a substantial improvement of the occupational security and the working environment.
These objects are achieved according to the invention by means of a device as set forth in the beginning and designed in ac¬ cordance with the characterizing clause of claim 1. The said objects are also achieved by a method according to claim 13. Tests with a device and a method according to the invention have shown that exchange of tool inserts is possible in a short period of time of about 2-5 minutes and that an exchange to a strongly differing product category does not require more time than 12-20 minutes. Despite these enormous gains in the time, cost, security and environment fields the invention offers possibilities of improved and easi¬ er service of the tools and those parts which interact with the tools, entirely without that stress, which an idle press casting machine leads to. On the contrary the productivity increases and quite generally occurring machine errors can usually be taken care of quicker and more reliably thanks to the invention, which also allows
the use of preheated tools, the downtime of the machine thereby being decreased still more, in a pratical example with about 30 minutes.
Additional characterizing features and advantages of the present invention are set forth in the following descrip¬ tion, reference being made to the accompanying drawings, which show a few preferred but not limiting embodiments of the invention. The drawings show in detail: Fig. 1 a schematic lateral view of a device according to the invention with its parent tool and two different pa¬ rent tools respectively, shown in two different functio¬ nal positions, in a position for exchange; Fig. 2 a top view of the device according to Fig. 1, along the plane II-II in Fig. 1;
Fig. 3 a view from the left in Fig. 1, but the removal device has been moved to the left, where a parent tool is shown in different functional positions; Fig. 4 said parent tool according to Fig. 3 in a lateral view as well as top views of the two open halves; and Fig. 5 the tool locking in the machine in a vertical sec¬ tion along line V-V in Fig. 2.
In Fig. 1 the device according to the invention in its entirety 1 comprises a press casting machine 2, a remo¬ val device 3 and a handling device 54 for a parent tool 8 and its isolated halves 9,10 respectively. The press casting machine includes a stand 4, on which a lower sta¬ tionary machine table 5 is mounted, from which in its turn vertical bearers 6 project upwards, which are placed in the corner areas and support an upper machine table 7, which is vertically movable.
On lower machine table 5 said parent tool 8 is fastened in its press casting position, and it mainly comprises a lower half 9 and anupper half 10. Each one of these halves holds its half 11 and 12 respectively of in¬ serts 13. Lower parent tool half 9 is supported by four
supporting and spacing elements 14 on the stationary ma¬ chine table and mesh with vertical bores 15 by means of vertically projecting guide and locking pins 16, which preferably in the middle of and on two diametrically op¬ posite sides are provided with milled locking cuts 17, the lower limiting surface 18 of which suitably slants downwards and outwards to provide a clamping with a wedge action, which is caused by end 19, which is bifur¬ cated in this case, by means of a locking bar 20. These locking bars are displaceably mounted in the lower and the upper machine table in horizontal control bores 21, the inner end areas of which cross said bores 15. Bi¬ furcated end 19 can then be designed as a separate part, which is introduced in said machine table from above through e.g. an opening 22, which is closed by means of a locking block 23, which is fastened to the machine table by means of bolted joints 24. Locking bar 20 or an extension of the proper bar meshes with a flanged end 25 with a coupling cut 26 in a rotary-symmetrical coup¬ ling end 55 of bifurcated end 19, with opening 27 of which a guide element 28 meshes from above, which is fastened in locking block 23 by means of a screw 29, and which prevents a rotation of the bifurcated end in cont¬ rol bar 21 and in relation to the respective locking pin 16. Furthermore, in Fig. 5 a guiding profile 30 for the movements of the bifurcated end is shown and a covering plate 31, which uncover a hollow space 32 and which is fastened by means of screws 33. Finally a stop block 34 is provided in the lower left end of hollow space 32 and fastened by means of screws 35.
Supporting and spacing elements 14, from which pins 16 project downwards, are fastened in lower parent tool half 9 by means of threaded bolts 36, which can be int¬ roduced from below or from above in said half.
As also is shown in Fig. 5, the bifurcated end is at its bottom provided with corresponding slanting surfaces 37
as surfaces 18, whereas upper limiting surfaces 38 of cuts 17 also in their locking position are placed at a distance above the bifurcated end, whereby an adequate locking force always is secured, also when a certainwear has occurred.
Each one of locking bars 20 is attached to its hydraulic cylinder 39 and is simultaneously actuated to be locked and released respectively via e.g. a machine central unit (not shown) . Each machine table is provided with e.g. two locking bar pairs, mounted on two opposite sides of the respective table. The lower as well as the upper parent tool half are fastened in the respective machine table in a preferably corresponding way. However, normally no support and spacing elements are required at the top, and thus the upper parent tool half can directly contact the upper machine table.
Figs. 3 and 4 show, how parent tool 8 can be fastened to the respective machine table and be released therefrom also by means of preferably two coupling elements 40, mounted diagonally on the upper machine table. Each of said elements comprises a hydraulic torsional cylinder 41, which projects downwards from the upper machine table and downwards is provided with a torsional plunger 42 with a horizontally projecting gripping element 43, which is designed to mesh with a e.g. downwards, forwards and on one side open gripping cut 44 on said diagonally opposite places in the respective sides of lower parent tool half 9. Fig. 4 shows that the torsional cylinders are designed to turn plungers and gripping elements a quarter of a revolution in order to attain a coupling between the upper machine table as well as the lowerpa¬ rent tool half with' the upper tool half mounted there¬ between. In this position are, as is shown in Fig. 3, the locking bars of the lower parent tool half suitab¬ ly released automaticly and in sequence with the grip¬ ping movement of the torsional cylinders, and in this
way the upper machine table can be lifted with the entire parent tool suspended from it. The upper parent tool half then suitably, i.e. for security reasons, can be locked to the upper machine table by means of associated locking bars, which otherwise also can be released automaticly, when the torsional cylinders are actuated into a gripping position, provided this is deemed adequate for security reasons. When a casting is done, the torsional plungers are released from the lower parent tool half, and in this way the two tool halves can freely be opened up and closed, The two tool halves are then locked to the respective tables by means of their locking bars.
The drawings also show, that the lower parent tool half is provided with so called core pulling devices 45, ope¬ rating rod 46 of which projects horizontally from the respective side of said half and is terminated in the form of a coupling head 47, which e.g. is provided with a flange 48 on all sides. The coupling head is designed to mesh from above with each one of coupling cuts 49 as¬ sociated with end 50 of a core pulling cylinder 51, which is fastened to the lower machine table and is activated during the casting. When the entire parent tool is to be lifted, the operating rods are placed in their in the associated tool half inserted position and the coupling heads can be lifted upwards from their cuts 49 without having to change the position of the core pulling cylin¬ ders. When later on the lower tool half is to be re¬ turned to its casting position, the coupling heads are automaticly inserted in said cuts 49, which have a V- or U-shaped opening 52, those edge areas of said ope¬ ning, which face cylinder 51, being shielded by a loc¬ king flange 53.
Particularly in Fig. 3 connections 56 and 57 for coolant passages are also shown, which passages connect the re¬ spective tool half with the respective machine table, male and female parts, not shown in detail and provided
with seals, meshing automaticly with each other, when the tool halves are coupled with the machine tables, in such a way that a coolant automaticly can circulate through the tool halves and cool the same during the casting.
On the lower machine table a rail pair 58 is mounted, which at one side of the machine is provided with an adjustable stop element 59, designed to limit the insertion move¬ ment of a tool carriage 60, which constitutes a part of said removal device 3, the other part of which is amain carriage 61, on which one or preferably two tool carri¬ ages can be stored and run perpendicularly to the remo¬ val directions of the main carriage (see Fig. 2) . The main carriage has a stand 62, supported by wheels 63, which in their turn run on floor rails 64, which lead from the machine to e.g. a service place 65. On themain carriage preferably two rail pairs 66 and 67 are mounted, the direction of which is perpendicular to the displace¬ ment directions of the main carriage. Said rail pairs are designed to be connected to the machine-connected rail pair 58, a position fixing device 68 being actuated. The latter device can comprise a pneumatic cylinder 69, pis¬ ton 70 of which pushes a locking fork 71 upwards, which from below holds one of the two connection areas, by means of which the position of the main carriage canbe locked. The tool carriages are also designed to be po- sitionally fixed on the main carriage by means of prefe¬ rably one permanent stop 72 on the main carriage on the side, which is turned away from the machine, and a tem¬ porary stop 73 on the side, which is turned towards the machine. Stop 72 can be a raised part, which is screwed on, whereas stop 73 suitably is a spring-loaded rocker arm, one end of which during the locking function pro¬ jects upwards above' the rail level in order to prevent the tool carriage from rolling off from the main carri¬ age and in a neutral position is pivoted verticallyto a level below the rail level against the action of said spring force, the tool carriage being able to roll off
from the main carriage and into the machine on its rail pair 58. The neutral position is obtained preferably au¬ tomaticly by letting said piston 70 or locking fork 71 actuate the other end of the rocker arm in a way which is shown with dashed lines in Fig. 1. The main carriage can be halted in the respective coupling position in a suitable way, already known per se, e.g. by means ofmic¬ ro switches or two manual stops, among which the pre¬ sently used ones can be chosen. The main carriage can be displaced manually or by means of a suitable driving de¬ vice, already known per se, preferably a pneumatic en¬ gine, the driving device suitably having a larger gear change in order to obtain a low speed and a high coup¬ ling precision.
Each tool carriage 60 is suitably provided with a dri¬ ving device 74, e.g. a pneumatic engine having a chain gearing 75 with large driving wheels 76, which via shafts 77 drive small carriage wheels 78 in order to obtain, al¬ so in this case, a low speed and a high coupling preci¬ sion. All carriages 60,61 are, when they are engine-dri¬ ven and when the control is completely or partially au¬ tomatic through ducts respectively, connected to a cont¬ rol center, not shown.
A tool change by means of a device according to the pre¬ sent invention is done in the following way: In Fig. 3 the working position of the press casting machine is shown with dot/dash-lines as to the upper machine table. If now a change to other inserts is to be done and pos¬ sibly even to other parent tools, then the upper machine table is removed to the raised position, shown in Fig. 3 with continuous lines, with the entire parent tool be¬ ing suspended from«the upper machine table, which is shown with dot/dash-lines. However, before the upper machine table is lifted, a number of preliminary opera¬ tions have to be done. First of all the coolant feeding is disconnected and the coolant in the coolant passages
in the two tool halves are emptied. The emptying is done through suction. The core pulling devices 45 are comple¬ tely inserted. Preferably through synchronization cylin¬ ders 39 of the lower machine table are now activated to pull locking bars 20 and release bifurcated ends 19 from pins 16 simultaneously with an activation of the torsio¬ nal cylinders in order to pivot gripping elements 43 into cuts 44. The synchronization is done in the simplestway by having cylinders 39 and 41 connected in the same pres¬ sure medium circuit. In this way only one trigger device for the two cylinders/functions is needed. Now the upper machine table is lifted according to the description above and into the position shown in Figs. 1 and 2, in which the main carriage is coupled to the press casting machine, one of the tool carriages being moved into the machine below the raised parent tool, which then is low¬ ered onto the carriage by lowering the upper machine table, cylinders 39 of which thereafter being activated to release lock bars 20 from pins 16. The torsional cy¬ linders are then activated to release the entire parent tool from the upper machine table. The cynchronization described above results in that cylinders 39 of the low¬ er machine table are reactivated to bring back bars 20 to their locking position, which however is unimportant, since the bars at the moment do not mesh with any locking pins 16. The machine table is now raised without any tools to an upper position and in this way the carriage and the entire parent tool on top of the carriage can be brought back to the main carriage, which now can be removed to a service place 65, in which there is e.g. an overhead crane or. the like as a handling device 54, by means of which the upper tool half can be lifted off from the lower tool half and be turned upside-down (see Fig. 3) , e.g. the inserts being_accessible to make an exchange according to Fig. 4, in which the sides of the two halves, which are turned towards each other, are turned upwards and the upper half has been placed on the other tool carriage. Subsequent to the insert exchange in the
two halves the upper half is brought back to the lower half, the upper half being turned around to its congru¬ ent functional position and preferably a preheating of the inserts and the central part of the tool is nowdone, suitably through a hot air feeding, an induction or the like, the coolant passages possibly being used for an in¬ ner heating of the tool. Also, it possibly is suitable to blow hot air between the two halves, which suitably are kept at a certain distance from each other in order to be able to blow faster a large amount of hot air into the tool and along its contact surfaces. This distance can be provided by means of the handling device and/or by means of temporary active external or internal spa¬ cing elements. Of course, said exchanges to not have to be limited to an insert exchange, but arbitrary parts, e.g. cores, can be exchanged, inspection can be done, cleaning, repair jobs etc., at the same time or alterna¬ tively. Also, another complete parent tool can be ready and be inserted into the machine in immediate connection with the removal of a parent tool mounted in the machine. Due to all these measures and possibilities the smallest possible loss of production time and minimum manual and above all uncomfortable efforts are allowed.
When another parent tool or a parent tool having ex¬ changed parts is to be installed in the machine again, the main carriage having a machine rail pair, which mat¬ ches the used tool carriage rail pair, is positioned and now in accordance with the description above simultane¬ ously a locking of the main carriage and a release of the tool carriage is done, the latter now being run in¬ to the machine below the raised upper machine table, which subsequently is lowered to a contact with the up¬ per side of the parent tool. The upper tool half is now locked against the upper machine table and the torsional cylinders are activated in order to mesh with cut 44 of the lower tool half, subsequent to which the upper machine table is lifted again together with the parent tool and the tool carriage can be removed from the machine. The
upper machine table is now lowered to its lowest posi¬ tion, which is the same as the casting position, the tor¬ sional cylinders are activated in order to release grip¬ ping elements 43 and simultaneously the lower cylinders 39 project their bars 20 to a locking position. As soon as the two tool halves contact the respective machine table, the coolant connections are connected to each other again and the coolant feeding can be started again.
Thanks to the described and shown design the core pulling devices do not put any obstacles in one's way to achieve an automatic disconnection and reconnection and what is required is only a raising of heads 47 out of cuts 49 and a lowering thereof into said cuts again. All this is done automaticly, since the heads are mechanically operated in order to move them into their inserted posi¬ tion, when the parent tool is lowered onto the lower ma¬ chine table. The mechanical operation can be done bymeans of locking shoulders 79, which are fastened to the upper tool half. The latter is also provided with two swinging axel pins 80, which project outwards on opposite sides in order to be able to in a simple way grip this half by means of a lifting device and to turn it around (see Figs. 1 and 3) .
It is shown in Figs. 1 and 2, that a tool carriage pas¬ ses, when it is moved between the main carriage and the machine, one of the core pulling devices. This is fea¬ sible, since the tool carriage is sufficiently high and is provided with a central through hollow space in the longitudinal direction , by means of which the tool carriage straddles said core pulling device, which in this way does not have to be moved to another position.