IL34805A - Injection and blow-moulding machine - Google Patents

Description

INJECTION AND BLOW-MOULDt NO MACHINE THE INVENTION relates to a combined injection and blow-moulding machine of the type having a nozzle mould plate and a counter-mould plate which is able to move back and forth in the direction of closure* between which plates there are arranged at least one injection moulding chamber and at least one blow-moulding chamber divided at right angles to the direction of closure, and also a carrier head which is able to rotate and move in the direction of closure, on which cores are arranged at angles of 90° relatively to one another about the axis of rotation of the carrier head and are able to be pivoted out of an Injection position into a blow-moulding position* The blow-moulding of plastics components has a number of advantages over the injection moulding process, because the blow-moulding process makes it possible to produce hollow components which can only be produced at great cost, if at all, by the injection moulding process* It is known in the art to use a combination of extrusion and blow-moulding when the blow-moulding machine is fed with an extruded tube* The finished articles have comparatively large internal stresses while welds and welded seams result which may require subsequent machining* The wall thicknesses of the finished articles are uneven, particularly in the vicinity of sharp corners and edges because the material is not sufficiently well guided in the mould during blowing* Swiss Patent No* ¾39 692 discloses a combined injection moulding and blow-moulding machine having a nozzle mould plate, a counter—mould plate and an intermediate a which is able to pivot about an axis at right angles to the direction of* closure of* the machine* The counter-mould plate and the intermediate plate are able to move on slide bare of the machine. Inside the nozzle mould plate there is an injection moulding chamber and within the counter-mould plate a blow-moulding chamber* The carrier head o carries* at 180 relatively to each other* wo blow—moulding cores which are positioned alternately in the injection moulding and the blow-moulding chambers* When the machine is in operation* every time a blank or parison has been formed in the injec ion moulding chamber, the counter-mould plate and the intermediate plate are moved away from the nozzle mould plate* The carrier head is then pivoted through 180° so that the blank enters the blow-moulding chamber* There in the next part of the cycle the finished article is blow-moulded* When the machine next opens* the carrier head is pivoted further so that the blow-moulding core carrying the finished article moves into a removal position and then back into the nozzle mould plate* During each step of the machine cycle* a blank may be injection moulded and a finished article blow-moulded* In this conventional combined injection moulding and blow-moulding machine* the considerable distance which has to be travelled by the mould plates for each pivotal movement of the carrier head through 180° is found to be a disadvantage since the mould plates have to be moved apart for a distance equal to twice the length of the finished article plus a safety margin* Such large distances* in conjunction with the considerable pivotal movement of the blow-moulding cores cause the blank to cool down considerably so that it becomes a difficult matter to control the temperature* German accepted Specification 108¾ 908 describes an injection moulding and blow-moulding machine of the type above described in which the carrier head is able to pivot about an axis parallel to the direction of closure of the machine. The injection moulding chamber and the blow-moulding chamber are in each case divided at right angles to the direction of closure. To enable the carrier head to be rotated* the arbor of the carrier head must be able to slide in the direction of its length. Because of this requirement and because the carrier head is always rotated further In one direction, there is no provision for heating the blow-moulding cores - an operation which is almost impossible* There are consequently considerable difficulties associated with temperature control. Obviously the injection moulding process must be carried out while the material is in an over-heated state, so that extra cooling stations for the finished article are required. Since the injection moulding chamber and the blow—moulding chamber extend at right angles to the direction of closure of the machine, the machine can, for reasons of space, not be constructed as more than a double unit since otherwise there would be no room for the carrier heads whose blow-moulding cores move in a single plane. The transverse dimensions of the machine would be exceptionally large. German Gebrauchamuster 1 777051 describes a further similar device.

French Patent 1 515666 discloses a compression moulding and blow-moulding machine having a carrier head for four blow-moulding cores which are shifted through, 90° relatively to each other. The cores pass through a heating station, a compression moulding station, a cooling station and a blow-mould t e th h s hine able difficulties are obviously encountered in connection with heating^>ecause two temperature—adjusting stationst viz, a heating and a cooling station* are necessary. This of course means that the cycle speed of the machine is reduced.

It is an object of the invention to produce a combined injection moulding and blow-moulding machine to produce articles blow-moulded from injection moulded blanks and of satisfactory quality at a nigh rate* tie machine is designed to make as economic as possible a use of the capacity of an injection moulding machine, so that it may be combined with other like machines according to the capacity of the injection moulding machine and can operate satisfactorily with, the opening distances of conventional injection mouldin machines* In accordance with the invention* there is provided on either side of the injection moulding chamber* which extends in the direction of closure* two blow-mouldin o chambers each arranged at an angle of 90 to the injection moulding chamber* the carrie head is able to pivot back o and forth through an angle o 90 about a preferably vertical axis which is at right angles to -the direction of closure, together with two blow-moulding cores which form a pair, so that when the carrier head is in one of its end positions one of the blow-moulding cores is located in the injection moulding chamber while the otiter is in one of the two blow-moulding chambers* while whenever a blow-moulding core pivots out of the blow-moulding position and into the injection moulding position* an associated stripper plate is able to move in the axial direction of the blow-moulding core by means of a guide roller which runs on the guide section of a guide plate* The fact that the carrier head pivots back and forth o machine as compared with a conventional machine producing an injection moulding of equivalent length* The opening distance only needs to be increased by a safety margin beyond the length of the injection moulding because the amount of displacement of the carrier head relatively to the counter-mould plate may be so small that the carrier head does not hit agains the counter-mould plate. The small aperture distance in combination with the slight pivotal distance of the carrier head makes possible a high-speed cycle* Since the carrier head is only pivoted back and forth, it is a simple matter to establish the necessary connections for t e working fluid because flexible tubes are sufficient.

Rotary-type connections are not required. As a result, it is also possible to heat the blow-moulding cores without any difficulty — a fact which is of great advantage for temperature control within the blow-moulding machine. In the injection moulding chamber the blank is formed on the heated blow-moulding core and carried on this heated core into the blow-moulding chamber. The cooling of the blank is thus prevented. Because the blow-moulding core is heated, there is no need to heat the i jection material. Within the blow-moulding chamber the finished article is cooled on the walls of tile blow-moulding chamber, so that no additional cooling is required inside the machine. The injection moulding chamber may be provided with a heat exchange system for the walls of the chamber so that it is possible to heat or cool the injection moulding, according to the working conditions and the material used. The blow-mouldin chambers are also provided with a heat exchange system to enable the blow-moulding chamber to be cooled.

It has been found of advantage to keep the injection moulding chamber cooler than the blow-moulding core, so that during injection moulding it is possible for the material to solidify sufficiently on the blow-moulding core* The walls of the blow-moulding chamber are also cooled, in order to ensure that the workpieces ' cool down as quickly as possible after blow-moulding* The mould plates of the injection moulding chamber and the blow-moulding chamber do not abut directly one against the other so that heat transfer is not very effective at this point* Hence it is possible without difficulty to maintain the walls of the injection moulding chamber and the blow-moulding chamber at different temperatures* When the blow—moulding core pivots back out of the blow-moulding chamber into the injection moulding chamber a stripping action is effected automatically by the stripper plates* This ensures great reliability in operation* Hence the invention does not require the conventional injection moulding machine to be enlarged for the purposes of injection moulding din conjunction with blow-moulding, but merely the use of a special injection and blow-moulding machine* The waiting times within the machine are shorter than in conventional moulding machines, this being due in particular to the afoovementioned heating or cooling of the various mould chambers* This results in a high cycle speed* The opening times also, do not need to be increased appreciably beyond those of conventional injection moulding machines because the displacement and pivoting of the carrier head may be effected during the moving apart of the two parte of the tool* The finished articles produced using a combined in from sprue. There is no difficulty as regards deformation*; The apertures and thread dimensions ma he achieved within closer* exactly predetermined tolerances* Threading may be formed us ng screw dies of an type which may be built into the strippe plates of the carrier head* In a further embodiment of the invention* the carrier head is able to move back and forth in the direction o closure under the action of a double-acting hydraulic cylinder* the casing of which is connected to a frame while the piston rod is attached to the counter-mould plate* This means that it is possible for the carrier head to move away from the counter-mould plate during the withdrawal movement of the latter, so that the pivot-in o the carrier head is possible at the point of reversal of movement of the counter-mould plate* In order to pivot the carrier head, the carrier head may be provided, at right angles to an arbor, with a gear segment engageable by a rack which is moved by a hydraulic cylinder.

The invention makes possible the setting up of a multi-machine arrangement in that a number of pairs of blow-moulding cores may be arranged in the direction of the axis or arbor* Hence one carrier head per moulding tool is sufficient. Since the blow-moulding cores are arranged in succession in the direction of the axis of the carrier head, the spatial requirements in the axial direction are determined only by the number of injection moulding chambers* In a preferred embodiment, the stripper device may comprise two guide plates arranged on either side of a frame and are located opposite each other so as to define the guide plate is provided* on its side adjacent to the carrier head with profiled grooves fo the guide rollers* In order to ensure that blow-moulding may be ef-feeted with, the correct timing and only when the two portions of the mould have been fully brought together, each blow-moulding core may be provided with a valve hich is connected to a compressed air duct within the carrier head while a setting device pretensioned in the ·; direction of closure has a set bolt which is actuated when the two halves of the blow—mould have been brought together and opens the valve located in the blow-moulding chamber.

The invention will now be described in detail in respect of a preferred embodiment, reference being made to the accompanying drawings, in which* Figure 1 is a combined injection moulding and blow, moulding machine according to the invention shown diagrammatically in section in a first working position; Figures 2 to 6 show further working positions of the machine shown in Figure lj Figure 7 is an enlarged view of the machine, the carrier head being shown particularly in the direction of the axis of the said carrier head; Figure 8 is a further-enlarged view in partial section along the line VIII-VIII in Figure 7? Figure 9 is a section along the line X-IX in Figure 8, and Figure 10 is a section along the line X-X in Figure 8.

A combined injection moulding and blow-moulding machine according to the invention is divided trans mould plates* mould inserts* cores* ejectors* nozzle heads and the like* These parts are largely conventional in an injection moulding machine so that they need not be described in detail. These parts are mounted on slide bars of the injection moulding machine and are slldable thereon under the action of hydraulic cylinders* Of the device of the invention. Figure 1 shows a nozzle mould plate 1 and a counter-mould plate 2* Within the nozzle mould plate 1 there is located an injection mouldin chamber 3* preferably in a mould Insert which is not illustrated* In addition* the nozzle mould plate 1 is provided with an injection nozzle ¾· The injection moulding and blow—moulding device of the invention has as Its most Important component a pivotal carrier head 5» The carrier head 5 is mounted on a separate frame which will be described below and is able to slide independently relatively to the counter-mould plate 2. The carrier head 5 is able to pivot about an axis 6 perpendicular to the plane of the drawing* The carrier head 5 carries two blow-moulding cores 7 and 8 which form a pair and stripper plates 9· The nozzle mould plate 1 and the counter-mould plate 2 each carry matching halves 10 and 11 of the blow-mould* The two blow-mould halves 10* 11 form a blow-moulding chamber together with the appropriate blow-moulding core 8 or 7· The mode of operation of the injection moulding and blow moulding device of the invention Is best described by explaining a full operating cycle with reference to Figures 1 to 6, Figure 1 shows the injection moulding and blow moulding device in closed position immediately after the closure movement has been completed* The blow-moulding blow—moulding chamber which is composed of the halves of the blow mould lO. ne blow-moulding core 7 is empty and is located in the injection moulding chamber 3 of the nozzle mould plate 1· Once the closure movement has been completed the combined i jection moulding and blow-moulding operation commences, Figure 2» Material is injected from t e nozzle h into the injection moulding chamber 3* thus forming a new blank 13» At the same time, the nozzle of the blow—moulding core 8 is pressurised, so that the blank 13 within the blow-mould constituted by the two blow—mould halves 10 is blown up to form the finished component l . Subsequently the nozzle mould plate 1 and the counter-mould plate 2 move apart as shown in Figure 3t at the same time the carrier head 5 is moved away from the counter—mould plate 2· the blank 13 and finished article l are located on the blow-moulding cores 7 and 8 respectively. When the injection moulding and blow-moulding device is open, the carrier head 5 pivots, through the position shown in Figure , through 90° about the axis 6 in a clockwise direction to the position of Figure 5· The blow-moulding core 7 together with the blank 13 is thus pivoted into the range of action of the halves of the blow mould 11. Coupled with the pivotal movement is the movement of the stripper plate 9 of the blow-moulding core 8, which acts to remove the finished article 1¾. At the end of this pivotal movement, as is shown in Figure 3, the blow-moulding core 8 is located in the effective range of the injection moulding chamber 3 and the blow moulding core 7 in the effective range of the blow-moulding core 11. Ihe carrier head 5 is now in position for the next injection moulding and blow moulding operation. The device is closed by means of the system actuating the injection in the injection moulding chamber 3· In the following part of the cycle, new material is injected through the nozzle to form a blank or parison on the blow-moulding core 8 and the blank 13 is blown on the core 7 in the blow-moulding chamber. This part of the cycle is similar to that shown in Figure 2, The injection moulding and blow-moulding device is now re-opened and the carrier head pivoted through 90° counter-clockwise, the finished article being stripped from the hlow-moiiding core 7· After this pivotal movement and closure of the injection moulding and blow-moulding device, the parts are again in the position shown in Figure 1· The axis 6 normally extends vertically since it is possible for the carrier head to pivot in this direction without a counter-balancing weight. When the arbor 6 extends horizontally within the injection moulding machine, it is necessary to compensate the eccentricity of the carrier head.

The lay-out and construction of an injection moulding and blow-moulding device of the invention is now shown in detail in Figures 7 to 10, Figure 7 is a diagrammatic view of a nozzle carrier plate 15 on which the nozzle mould plate 1 is located with the intermediary of a number of spacer elements, A carrier plate 16 is shown on the opposite side and on this the counter-mould plate 2 is mounted by means of spacer elements l6» . The slide bars of the injection moulding machine for the injection and blow moulding device are not shown.

The nozzle mould plate 1 contains the injection moulding chamber 3 which is not shown in Figures 7 to 10 and the walls of which are provided with a heat exchange system which makes ossible th ahievin of either a heatin or the injection moulding chamber* the blow-mould halves 10 whic are held in position by threaded bolts. These mottld halves 10* are also provided with heat exchange elemen s which make possible in particular a cooling of the halves of the blow mould* The surfaces of contact between the halves lO of the blow mould and the nozzle mould plate 1 or the counter mould plate 2 are not made extremely flat and even, so that heat transfer between these surfaces is not efficient. As a result, it is easily possible to maintain the walls of the injection moulding chamber at a temperature different from that of the halves of the blow mould. s A frame 17 for the carrier head 5 provided with a traversing plate 18 and bearing plates 2&. The cylinde portion of a hydraulic, piston and cylinder arrangement 19 is secured to the traversing plate 18 while the piston rod 20 is Inserted in the counter-mould plate 2. , The counter-mould plate 2 carries guide strips 2¾· between which the bearing plates Zh are guided on the upper and lower surfaces of the injection and blo moulding Cfcdevice. The double-acting hydraulic cylinder thus makes possible a shifting of the frame 17 with the carrier head 5 within the guide strips Zh* on the counter-mould plate 2. O the frame 17 is located a further hydraulic cylinder arrangement 21. the piston rod 22 of which is coupled with a rack 23, as shown in Figure 9. In order to pivot the carrier head 5 the bearing plates Zh each support a sub sha t 25 of the carrier head. In addition, the carrier head 5 is provided with a geared segment 26 which meshes with the rack 23. When the injection and blow-moulding device of the invention is constructed as a double arrangement, this gear segment 26 is located at the centre of a common arbor for the carrier heads. The translation The carrier head 5 carries t¾e two blow-moulding cores 7 and 8 which constitute a pair and ar arranged at an angle of 90° relative to each other within a plane radial to the axis of pivot 6, Plgure^.10 only showing the core 8 completely* In a machine with several devices of the invention t a number of such pairs of cores are arranged in succession, i.e. spatially one above the other* Each blow-moulding core 8 has a mould which is designed for the blank concerned* The blow-moulding core 8 is conventionally connected to the carrier head 5 by means of bolts and other fasteners* Passages 27 permit an insert 28 to be heated* Heating may be effected by oil in the manner shown* Electrical heating is also possible* Within the core there is a substantially axial passage 29 which receives a valve rod 3 and insert 31· The valve rod 3 merges into a head 32 which extends into a bore 33 within the carrier head 5* A helical spring 3¾ tensions the valve insert 31 in the direction of closure* A bore 35 opens transversely into the bore 33 and contains a set bolt 36. This bolt projects out of a hole 37 in the carrier head 5· The set bolt 3 is also provided with seals* The set bolt 36 and head 3 have matching inclined surfaces 38.

The helical spring 3^ tensions the valve rod 30, restressing It in the direction of closure, thus causing the end face of the set bolt 36 to be raised out of the hole 37» (see Figure 10, bottom of drawing as Illustrated fo the core 7)· A passage 39 for compressed air also opens into the bore 35· FigurellO shows an arrangement of the carrier head 5 In which the blow-moulding core 8 is located within the blow moulding chamber formed by the halves 10 of the mould* The passage 39 here extends pass through a line 4l¾ passage 4θβ passage 39· bore 35 and passage 2 to reach the valve insert 31· In the closure position shown in Figure lO, the set bolt 36 is inserted by the thrust from the counter-mould plate 2, so that the valve insert 31 is raised from the valve face* As a result* the air used for blow-moulding is able to flow into the core 8 and blow out the blank to form the finished article* Figure 10 also shows the corresponding actuating elements and lines for the blow-moulding core 7 which, in the position Illustrated in Figure lO is located in the injection moulding chamber 3 of the nozzle moulding plate. The air ducts are in this case not filled with compressed air* ΏΧΘ stripper plate 9 is controlled by means of guide rollers 42, as shown in Figures 7 and 8* The stripper plate 9 is moreover, guided in a passage 44 in the carrier head 5 hy means of a pin 43 carrying a stop collar 45. The guide rollers 42 are preferably arranged at either side of the stripper plate 9* To control the guide rollers 42» two guide plates h are arranged at eithe side and are able to fold about axes 46, Returning devices (not shown) are also provided for the guide plates 4 to hold the guide plates ^7 in position against the side surfaces of the carrier head 5· Bach guide plate 47 has a guide section 48 on which one of the guide rollers 42 moves, thus raising the stripper plate to the head of the core* In addition a profiled groove 49 is cut on the inside of each guide plate 47 and in this, for example* as is shown in Figure 7» the guide roller 42 of the blow-moulding core 7 enters the blow-moulding chamber when it is pivoted out of the injection moulding chamber* The guide plate the blow—moulding core 8 is influenced by the appropriate guide section ¾8, so that the finished article Is stripped from the core 8 in accordance with the sequence of movements shown in Figures 3 to 5· The stripper plate 9 always remains stationary in raised position and is retracted when the halves of the mould move into initial position, the guide rollers ¾2 moving in the slot between the guide plates ¾7» In the appropriate stripper plate 9* semi-circular threading dies 55 are inserted, Figure 10 showing the surfaces dividing a semi-circular threading die* The threading dies 55 are guided on strips 56 which are secured to the stripper plate. Springs 57 prestress pairs of threading dies 55 1» the direction of lift towards each other* FlgurelO shows that the plane of osculation of the threading dies is shifted through 90° relatively to that of the halves of the blow mould 10. In Figure 8 the plane of osculation of the threading dies 55 is arranged perpendicular to the plane of the drawing* On the rear surface the threading dies 55 have inclined faces 58» When the stripper plate 9 is in retracted position as is shown in Figure 8* the threading dies 55 &Γβ urged together against the action of the springs 57 o The power required for this purpose is achieved by means of wedge-shaped members which are clamped to the carrier head but which are not shown in the Figure and co-operate with the inclined surfaces 58. Xihen the pivoting of the carrier head causes the stripper plate 9 to be raised, the threadin dies will be pressed apart by the action of the springs 57 so that the threaded neck of the finished article is released* The various parts of the device engage by means of always accurately positioned relatively to the mould plates 1 and 2, the carrier head 5 has guide bolts 53 of which one is shown in Figure 7· The nozzle mould plate 1 is provided with bores 5¾ to receive the guide bolts 53· In order to exclude the possibility of malfunctioning of the machine, sensor arms 50 are mounted on the shaft of the carrier head 5* each of the said arms carrying a scanning member 51 for a micro*switch 52* This means that the exact positioning of the carrier head can always be checked as the parts of the device move together* The hydraulic cylinders 19 and 21 are inserted in the overall control system , for the machine* The various platens carry micro-switches and sensors which are not shown in detail but which initiate the various operations* The hydraulic cylinders 19 and 21 can consequently be actuated at suitable stages of the movement of the injection moulding machine with pressurised fluid, so that the carrier head 5 is moved with correct timing in the manner shown in Figures 1 to 6.

The injection moulding and blow-moulding machine of the invention is designed fo the production of any bloxi-mouldings desired. In particular the i jection and blow-moulding device of the invention may be used to produce bottle-shaped containers, glasses with a re-tracted/drawn in edge and the like.

Claims (3)

What we claim 1st»

1. A injection and blow-moulding machine of the type described comprising two blow moulding: chambers ■whic are arranged one on eithe side of the injection moulding chamber which extends in the direction of closure, the two blow-moulding chambers being each at an angle of 90° relatively to the injection mouldin chamber, the carrier head being able to pivot back and forth through an angle of 90° about an axis which is at a right angle to the direction of closure, the carrier head having two blow-moulding cores which form a pair, so that when the carrier head is in each of its end positions one of the blow-moulding cores is located in the injection moulding chamber while the other core is located in one of the two blow-moulding chambers alternatively* each core having an associated stripper plate so that whenever a blow-moulding core is moved out of the blow-moulding position and into the injection moulding position, the associated stripper plate is able to move in the axial directio of the blow-moulding core,

2. A machine as claimed in Claim 1, wherein the stripper plate is movable by means of a guide roller which runs on a guide section of a guide plate,

3. A machine as claimed in Claim 1 or 2, wherein the arrow head is pivotable about a vertical axis, h9 An injection and blow-moulding machine as claimed in Claim 1, 2 or 3# wherein the carrier head is able to move back and forth in the direction of closure by means of a double-acting hydraulic cylinder arrangement, the cylinder portion of which is secured to a frame while the piston rod is connected to the counter-mould plate, 5· An injection and blow-moulding machine as claimed 6m An injection and biow-mculding machine as claimed in one of Claims 1 to 5» wherein a number of pairs of blow-moulding cores are arranged in line parallel with the direction of the axis of the carrier head* 7* An injection and blow—moulding machine as claimed in one of Claims 1 to 6, wherein two guide plates are arranged on either side of a frame and are located opposite each other so as to define a slot* each of the said guide plates being able to fold about an axis at right angles to the axis of the carrier head* while the guide plates are provided on their side adjacent to the carrier head with profiled grooves for the guide rollers. 8· An injection and blow-moulding machine as claimed in one of Claims 1 to 7, wherein each blow-moulding core is provided with a valve which is connected to a compressed air duct within the carrier head while a setting device pretensioned in the direction of closure has a set bolt which is actuated when the two halves of t e blow mould have bee brought together and opens the valve located in the blow-moulding chamber* 9· An injection and blow-moulding machine as claimed in one of Claims 1 to 8 wherein each stripper plate for each blow-moulding core carries two semi-circular threading dies which are pretensioned by means of springs so as to be urged together in the direction of lift, while the threading dies are able to slide on the stripper plate* 10* An injection and blow-moulding machine as claimed in one of Claims 1 to 9» wherein the walls of the injection moulding chambers and blow-moulding chambers and the blow-moufiding cores contain heat exchange systems so as to make it possible independently to control the temperature of the injection moulding chambers, blow—moulding chambers and injection moulding cores* 11, An injection and blow—moulding machine substantially as hereinbefore described with reference to the accompanying drawings.