US 3640663 A
A device and means for supplying high clamping pressure to split molds. The molds are mounted in side cover plates on elastic mountings. The cover plates can be clamped closed by simple clamping devices such as hooks. This elastic mounting eliminates the more complex clamping systems used when the split molds are directly clamped.
Description (OCR text may contain errors)
United States Patent Hampel et al.
[ 1 Feb. 8, 1972  DEVICE FOR FILLING CASTING MOLDS WITH HARDENABLE CASTING RESIN  Inventors: Gerald Hampel; l-lansgeorg Gruss, both of Vienna, Austria  Assignee: Optipatent AG, Zug, Switzerland  Filed: Nov. 25, 1969 2: Appl. No.: 879,793
 Foreign Application Priority Data Feb. 18, 1969 Austria ..1640/69  US. Cl ..425/233, 425/405, 425/449  Int. Cl ..B29c 5/00, B29f 1/00  Field of Search ..l8/30 JA, 30 LM, 30 LA, 30 LE, 18/30 NV, 30 NM, 30 NS, 30 NZ, 30 PA, 30 PC,
DIG. 60, 20 H, 30 AA, 30 AC, 30 LB, 30 LD, 30
 References Cited UNITED STATES PATENTS 3,270,115 8/1966 Nouel ..18/30 NV X 2,697,253 12/1954 Kruft ..18/30 LM 3,267,517 8/ 1966 Altermatt.... 18/DlG. 60 2,526,993 10/1950 Bower ..25/l29 2,351,774 6/1944 McGowen... 1 8/20 H 2,431,843 12/1947 Swoger ..18/20 H Primary ExaminerRobert D. Baldwin Assistant ExaminerMichael 0. Sutton Attorney-Dean Laurence [57 ABSTRACT A device and means for supplying high clamping pressure to split molds. The molds are mounted in side cover plates on elastic mountings. The cover plates can be clamped closed by simple clamping devices such as hooks. This elastic mounting eliminates the more complex clamping systems used when the split molds are directly clamped.
4 Claims, 6 Drawing Figures PNENTED F E8 8 I972 SHEET 1 OF 4 INVENTOR GERALD HAMPEL HANS GEORG GRUSS PATENTEUFEB 8 I972 3.640.663
SHEET 2 OF 4 I INVENTOR GERALD HAMPEL HANS GEORG GRUSS INVENT OR GERALD HAMPEL HANS GEORG GRUSS DEVICE FOR FILLING CASTING MOLDS WITH IIARDENABLE CASTING RESIN The invention refers to a device for filling casting moulds with hardenable casting resin supplied under pressure particularly in injection moulding.
One type of mould is mounted on a mould carrier which can be raised and lowered, and is divided on a plane transverse to the direction of movement of the mould carrier into two mould portions which are clamped together in the operating state. In casting, on injection moulding comparatively high pressures are advisable in order on the one hand to accelerate the casting process and on the other hand to ensure a satisfactory product. If moulds having large surface area at the joint plane are used, which is the case in particular when several objects are shaped in the same mould, on casting there is an excessively high pressure, which acts on the clamping means holding the mould halves together. With the known devices therefore, the clamping is a very expensive matter. Difficulties arise in particular on the clamping and unclamping of .the mould parts if excessively high pressures have to be coped with, and with these known devices there is high wastage due to wear.
The aim of the invention is to overcome these disadvantages and in the main consists in that the two parts of the mould are supported preferably elastically, against cover plates that are clamped to each other and arranged, when in the casting position, to be pressed between the mould carrier and an abutment,
As a result of this arrangement, the high pressure occuring on casting is taken up by the mould carrier and the abutment and the clamping means for the mould halves is relieved from casting pressure. If, for instance, the resin is supplied to the mould under a pressure of 2 atrn. to 3 mm, with suitable cross section of the mould, the total pressure acting on the two cover plates may amount to approximately 2 tons.
This pressure may be taken up without difficulty by the lifting mechanism of the mould carrier, which is normally a hydraulic mechanism, and by the abutment, which may be fixed. After the casting operation has taken place, the two cover plates remain clamped to each other until hardening is completed. The casting pressure no longer has efiect and a comparatively slight force, for instance, a force of a few hundred kilograms, suffices to hold the two portions of the mould closed together for this purpose. This pressure may be taken up by the clamping without its being necessary for this clamping to be of expensive construction. Above all, however, the invention offers the advantage that the high pressure of the two portions of the mould against each other is maintained for a short period only, during the casting or injection process, and during the period which is necessary for the hardening to take place the pressure is reduced. This advantage is particularly effective when the mould itself consists of a yieldable plastics material, which is deformable to a certain extent elastically or plastically, since in this case pressure maintained for a long time would damage the mould. By the fact that the two portions of the mould are supported elastically against the cover plates which are clamped to each other, the advantage is obtained that the clamping and unclamping of the two portions of the mould may take place in a simple way by pressing together the two cover plates. As a result, the clamping members are relieved of pressure and can be closed and opened without tension, so that wear on the clamping members may in practice be excluded. In this case it is possible to construct the clamping members simply as hooks.
In accordance with a preferred embodiment of the invention, the portions of the mould are supported against the cover plates with interposition of an elastic construction member, in particular a plate of foamed plastics material, for instance, foamed silicon rubber. The mould itself may also consist of elastic material, this elastic construction of the mould either being additional to the elastic support or itself forming the elastic support. One form of device in accordance with the invention, by which the mould is closed in a clamping station and opened in an unclamping station, is accordingly in the main characterized in that in both the clamping station and the unclamping station a pressing device is provided which presses the cover plates together. The force with which the two cover plates are pressed together during the casting or injection process can be of the same size or may optionally even be greater than the force with which the two cover plates are pressed against each other in the clamping and unclamping stations. In order to maintain the clamping with certainty during the casting or injection process, in accordance with the invention the clamping members may be pressed by spring pressure into the closed position.
Accordingly, it is possible to fill the mould under very high pressure and to ensure the closed position of the mould under all circumstances, without stressing the clamping members, the clamping members themselves, in spite of the high casting or injection pressure, being able to be of simple construction, opening and closing easily and without undue wear.
In accordance with the invention pressure-sensitive units may be provided which indicate the end of the filling process by a rise in pressure, when the mould is filled, so that in spite of the high casting pressure made possible by the device of the invention, no damage to the mould is to be feared.
The invention is particularly applicable in casting in vacua, wherein the mould in the known way is sealingly surrounded by a vacuum hood in the casting position. In this case, in accordance with the invention, the abutment may be fon'ned by the vacuum hood itself, or by a part connected to the said hood, it then being necessary simply to construct a seal between vacuum hood and mould yieldingly in such a way that resting against the abutment and sealing off are ensured simultaneously. This is obtained .by providing a seal on the mould or on the vacuum hood for sealing the vacuum hood, the deformation path of which seal is greater than that for the lift of the mould carrier after the top of the mould first engages the underside of the abutment.
The invention will be further described with reference to specific embodiments thereof, which are illustrated in the accompanying drawings in which:
FIG. 1 is an elevation of a moulding device incorporating a preferred embodiment of the invention;
FIG. 2 shows in section the position of the mould before casting;
FIG. 3 is a similar view showing the position during evacuation;
FIG. 4 is a further similar view showing the position during the casting;
FIG. 5 is a plan view showing a complete moulding arrangement;
FIG. 6 shows a detail of the mould with the cover plates on a larger scale;
The mould carrier 1 is formed by a table which may be raised and lowered hydraulically. 3 denotes a vacuum hood, which sealingly abuts on the mould carrier 1, by means of a seal 4 shown in the evacuation position in FIG. 3, and in the casting or injection position as shown in FIG. 4. The mould which consists of two parts, 5, 5' rests on the mould carrier 1, and is clamped between two cover plates 6 and 7 which are clamped to each other by hooks 8.
The casting resin is supplied to the mould via a mixing head 9, a flexible hose l0 and a filling valve 1 1, l2 and 13 (see FIG. 5) denotes supply containers which contain the resin components (resin and hardener), which are supplied to the mixing head 9. From the supply container 12 one resin component is supplied to the casting head via a pump I4 and a line 15. From the supply container 13 the other resin component is supplied to the mixing head 9 via a pump 16 and a line 17. The nonused portion is returned to the supply containers l2 and 13 respectively, by the return lines 18 or 19, so that premature hardening of the resin in the mixing head 9 is avoided.
The filling valve 11 consists of a sleeve 21 having a valve seat 22 and a valve cone 23 which is displaceably carried within this sleeve. The shaft 24 of the valve cone 23 is hollow and the supply hose is connected to this shaft. The outlet openings 25 from the hollow space 26 in the valve shaft 24 opens out into a hollow space 27 in the sleeve 21. In the open position of the valve cone 23, the outlet openings 25 lie at the top end of the hollow space 27, so that the latter has casting resin flowing through it continuously over its whole length, as a result of which the formation of residues in dead spots is prevented.
The outlet opening 28 from the valve 11 is surrounded by a seal 29 which forms the end face of the valve 11. The sleeve 21 is inserted displaceably in a sealing guide 30 of the vacuum hood 3, and may be displaced by means of a lever 34 which is carried on the vacuum hood 3 at 31 and actuated by a hydraulic cylinder 32 (see FIG. 1). The valve cone 23 is axially displaceable in relation to the sleeve 21. This takes place by means of a lever 35, which is carried on the sleeve 21 itself at 36 and actuated by a hydraulic cylinder 37.
In FIG. 6 the mould is shown in cross section on a larger scale. The lower portion 5 and the upper portion 5 are tensioned together with interposition of an elastic intermediate piece 2, by the lower cover plate 7 and the upper cover plate 6. This elastic intermediate piece 2 consists of foamed silicone rubber, which is resistant to the temperatures occurring. The mould 5, 5 itself consists of synthetic resin. 38 denotes a foil of foamed silicone resin interposed between the lower portion 5 of the mould and the intermediate piece 2. The hooks 8 are articulated to the lower cover plate 7 at 39, and engage on detents 40 fixed to the upper cover plate 6, and tension the upper plate 6 against the lower cover plate 7, as a result of which the portions 5, 5' of the mould are pressed together. The hooks 8 are pulled into the closed position by compression springs 41. In the center of the upper portion 5' of the mould, there is a casting gate 42. Round this casting gate, the upper portion 5 of the mould is left free by a circular hole 43 in the upper cover plates 6, so that the lower end face 29 of the valve 11 may seat sealingly on the upper portion 5' of the mould.
In the position shown in FIG. 2 the mould 5, 5' clamped between the cover plate 6 and 7 is arranged on the mould carrier l. The valve 11 is closed and the mould carrier is in the lowered position.
The mould 5, 5' clamped between the cover plates 6, 7, is then raised to the position shown in FIG. 3, in which the seal 44 of the vacuum hood 3 rests sealingly against an annular surface 45 on the lower cover plate 7. The vacuum hood 3 is fixedly arranged, and is rigidly connected to an abutment formed by a plate 46. The mould is pressed against this abutment 46 by the hydraulically raised mould carrier 1, so that the hooks 8 which clamp the lower cover plate to the upper cover plate, are relieved of pressure. As a result, the elastic intermediate piece 2 is compressed, although the hooks 8 remain in their closed position under the effect of the springs 41. The valve 11 is closed, but still remains in the raised position, so that the casting opening 42 in the mould remains free. In this position the mould is evacuated via a connecting piece 47.
In the position shown in FIG. 4, the filling of the mould with casting resin takes place. The valve 11 is lowered by the lever 54 to such an extent that the end face 29 of the sleeve 21 abuts sealingly against the portion 5' of the mould. The valve cone 25 is raised by the lever 35 and via the casting gate 42 in the mould, which lies opposite the outlet opening 28, the casting resin is poured under pressure into the hollow space of the mould 5, 5'. A rise in pressure recorded by a pressure-sensitive member, indicates that the mould is filled, and the filling process is then terminated. After the termination of the filling process, the valve cone 23 is again pressed on the seat 22, the space inside the vacuum hood 3 is pressurized and the mould carrier 1 is lowered to the position shown in FIG. 2.
Since the casting takes place under pressure, and the mould itself lies in a vacuum chamber, a force of several metric tons results, which strives to press the cover plates 6 and 7 apart from each other and to compress the elastic intermediate piece 2. This force is now taken up by the pressing of the upper cover plate 6 onto the abutment 46, with the result that the clamping members 8 are relieved of pressure. Accordingly, the great pressure of the mould 5, 5' between the two cover plates 6 and 7 takes place only during the casting process.
As can be seen from FIG. 5, after the casting process the mould is conveyed along a treatment path, for instance, through a tunnel 47, in which, for instance, setting can take place, under the effect of hot air. The various stations are indicated by the reference number 48. After passing along the treatment path, the mould, clamped between the cover plate 6, 7 reaches an unclamping station 49, where the unclamping takes place in a simple way by the two cover plates 6, 7 being pressed together by a press; the elastic intermediate piece 2 yields, so that the hooks 8 can easily be opened. The opening of the mould and the insertion of a new mould 5, 5' between the cover plates 6, 7 takes place at station 50. At station 51, the clamping of the two cover plates 6, 7 takes place, which now surround the newly inserted mould 5, S. This clamping may be carried out in a simple way if the two cover plates 6, 7, with compression of the elastic intermediate piece 2 are pressed against each other by a press, so that the hooks 8 snap into the closed position. The mould which has been clamped in this way then reaches the mould carrier 1 and the cycle is repeated.
Accordingly, the mould 5, 5' between the two cover plates 6, 7 is pressed under high pressure for a short time only during the casting process and during the evacuating, whereas it is under comparatively low pressure during the considerably longer period during which it passes along the treatment path What we claim is:
1. Apparatus for moulding items by filling casting moulds with a mixture of resin and a hardener, which apparatus comprises a plurality of casting moulds adapted for movement along a path, each of said moulds having a pair of mould halves which are disposed in abutting relation and form a casting cavity, having upper and lower cover plates which flank said mould halves, having elastic means disposed between one of said mould halves and the adjacent cover plate, having clamping means attached to said cover plates for interconnecting said cover plates and holding said mould halves in abutting relation and having opening means in the upper cover plate to provide an entry into the casting cavity, a filling station along said path having a device for filling said moulds with the resin-hardener mixture, which device includes vacuum hood means having abutment means in connection therewith, carrier means for supporting the lower cover plate of one of said casting moulds, means for carrying out relative vertical movement between said vacuum hood and said carrier to move said abutment means and said upper cover plate into abutting relationship and to press said mould halves together, seal means carried by said vacuum hood means for creating a seal peripheral of said opening into the casting cavity, means for connecting said vacuum hood means with a source of vacuum, filling valve means mounted in connection with said vacuum hood means for movement into said opening in said upper cover plate and into sealing relationship about said cavity entry, means for moving and said filling valve means into said sealing relationship, and means for supplying said resinhardener mixture to said filling valve means, and a heating station along said path for accelerating the setting of said resinhardener mixture in said filled casting cavity.
2. Apparatus in accordance with claim 1 wherein said clamping members are hooks which are urged into the holding position by spring means.
3. Apparatus in accordance with claim 1 wherein said filling valve is formed by a sleeve sealingly mounted in connection with said vacuum hood and axially displaceable and by a valve cone which is axially displaceable within said sleeve and seals against a seat carried by said sleeve, the lower end face of said sleeve abutting the upper mould half when said filling means is disposed in sealing relationship.
4. Apparatus in accordance with claim 3 wherein said valve cone has a hollow shaft and is connected to said supply means for the resin-hardener mixture, and wherein the hollow shaft contains outlet openings which lead into the upper end of an intermediate chamber within said hollow sleeve at the lower 5 end of which said seat is located so that said resin-hardener mixture flows through said entire intermediate chamber.