DE3101283A1 - Process and device for producing preforms (parisons) from thermoplastic - Google Patents

Abstract

For the production of preforms (parisons) first of all one heated end of a tubular section is formed on a first heated wheel. Subsequently the other end, also heated, of the tubular section is formed on a second heated wheel. A turning apparatus for the tubular sections is provided between the heated wheels.

Description

Method and apparatus for manufacturing

of preforms made of thermoplastic material The invention relates to a method and a device for producing preforms from thermoplastic plastic, with the pipe sections at both ends at the deformation temperature be heated, one end with the help of an inserted into the pipe section Support mandrel and a hollow shape is formed into a closed bottom, and on the other end with the help of an outer mold and a mandrel with a profile to put on a closure provided mouth is formed, the in Transport sleeves vertically held preforms on turntables at the individual Workstations for heating and forming are passed by.

Such systems are known (DE-AS 17 04 119). The pipe sections gripped in the middle by brackets, the two ends heated and closed to form one Bottom or to a bottle mouth reshaped. For this are the Preforms are held at intervals on the circumference of a turntable and are placed on heating devices passed. The forming tools are then used to close the floor and actuated to form the mouth profile. Such from pipe sections Manufactured preforms are then heated to blowing temperature into hollow bodies, in particular bottles, blow molded.

To heat and reshape both ends, the pipe sections must be between be held at the ends, with the clamping occurring during forming must absorb axial forces. This requires a corresponding length of the pipe sections. If pipe sections of shorter length are to be processed into preforms, so it is not possible to use the known method. Because the used nowadays thermoplastics when blowing into hollow bodies under a very high Degree of stretching, namely of a degree of stretching of a factor of 10 and above biaxial are oriented, it is assumed that the preforms are relatively short. but for other reasons it can be advantageous to process pipe sections, without these being held in the middle.

Proceeding from this, the invention is based on the object of providing a powerful Method and apparatus for producing preforms with a closed Specify the bottom and the mouth profile from pipe sections.

According to the invention, the object is achieved with a method in which the upper end of the pipe sections is heated on a first group of turntables and is transformed into a closed bottom, in which the preforms then rotated by 1800, and when on a second group of turntables the opposite top end of the preforms is heated and formed into a mouth profile is formed.

According to the invention, there is a division of the work processes. So will initially only the one upper end of the pipe sections is heated and reshaped and then the other end is heated and deformed. The execution of the procedure becomes essential facilitated by the fact that the preforms after leaving the first group 1800 are rotated and thus the other end to be heated to be deformed Preforms are directed upwards again.

Another advantage is that the heating devices, forming stations and partially transport sleeves for the preforms in the first and second groups can be designed the same or approximately the same.

The method according to the invention is also characterized in that the axial forces exerted by the molding tools on the preform via the each cold end of the preform can be taken up by the transport sleeves. There is therefore no need for the pipe sections and pipe sections to be clamped from the outside the design of the turntables is considerably simplified. Be in a simple way the preforms inserted into corresponding openings in the transport sleeves, which can be supported on stops in the axial direction.

In this way it is also possible to produce very short preforms.

In a further advantageous embodiment of the invention Procedure is in the second group of turntables which are enclosed in the outer mold Section adjoining mouth area of the preform by means of a stretching mandrel axially just and thinly drawn out, the closed one in the transport sleeve detected supported bottom of the preform. The bar presses on the in in the meantime, the bottom of the preform has cooled down and pulls the heated material of the mouth area, the outside of the by the mandrel in the outer shape anchored mouth area of the preform is here the transport sleeve arranged displaceably and the stroke of the stretching mandrel of a stop for the Transport sleeve limited. This extension of the preform has the advantage that Material is saved because material from the mouth area, which is not subsequently is blow molded, is displaced into the neck area of the bottle to be blown and so that it takes part in the blow molding.

The device for performing the method is defined in further subclaims marked.

An embodiment of the invention is shown below with reference to the drawing explained in more detail. It shows: FIG. 1 a plan view of the manufacturing device of preforms in a schematic representation, FIG. 2 shows a section through a Part of the heating wheel on an enlarged scale, FIG. 3 shows a section through the molding tools for closing the bottom, FIG. 4 shows a plan view of the turning device in FIG schematic representation, Fig. 5 is a side section through two chain links of the turning device, FIG. 6 is an end view of a guide link the turning device for vertical guidance of the chain links, FIG. 7 is an end view a guide member of the turning device at the beginning of the turning section, Fig. 8 shows a section through the forming tools for forming the mouth profile on second form wheel.

In Fig. 1, the overall system is shown in which the pipe sections made of thermoplastic material from a magazine 10 via an elevator 12 in a conveyor 14 are promoted in which they are isolated and in the longitudinal direction be published in a row. The pipe sections then fall into recesses on the circumference of a loading head 16, from which the pipe sections are pushed out radially and are taken over by gripper clamps of a loading wheel 18.

The pipe sections are thereby placed in transport sleeves rotating with the loading wheel 18 plugged in and handed over to an Eleizrad 20.

As can be seen from Fig. 2, on the circumference of the heating wheel 20 are a A variety of brackets 22 attached to which the transport sleeves 24 with the inserted pipe sections 26 are passed.

Furthermore, reflector devices 28 are located on the heating wheel about an axis 30 mounted pivotably by means of a cam roller system 32. The reflector device 28 has a lower opening 34 for the passage of the upper end to be heated Pipe section 26 and one of the stationary radiant heater 36 facing large opening. The radiant heater is arranged on the circumference of the heating wheel. When turning of The tube sections 26 together with the reflector device 28 become the heating wheel passed the radiant heaters, with the upper end of the pipe section on Forming temperature and the upper end face is heated to melting temperature. The pipe sections are then removed from the heating wheel 20 and transferred to a transfer station 38 transferred to a forming wheel 40.

As can be seen from Fig. 3, are not shown on the circumference Forming wheel 40 arranged a plurality of forming stations, which are driven by compressed air Form tools exist. In Fig. 3, the transport sleeve is in a manner similar to that on the heating wheel 24 held on the circumference of the forming wheel. By means of a compressed air servomotor 42 is a mandrel tip 44 through a bore 46 in the transport sleeve 24 and through the pipe section advanced to the level of the pipe end. Then the hollow spherical moves Form piece 48, which is driven by a servo motor 50, except for a predetermined, Stop, not shown, wherein the mandrel tip 44 supports the pipe end from the inside. In this way, the upper end of the pipe section is deformed to form a closed base and welded. The mandrel tip 44 is supported on the servomotor 42 and can opposite the fitting 48 evade. The lower cold end of the preform is supported at the bottom of the insertion opening of the transport sleeve 24. After molding and cooling the forming tools 44, 48 go back to their starting position and the pipe section is transferred with the transport sleeve 24 to the unloading wheel 52 in FIG. 1.

Via gripper clamps, not shown, arranged on the unloading wheel 52 the transport sleeves with the pipe section are removed from the forming wheel 40. Means one constructed in a manner similar to that in FIG. 2 Cam roller system the pipe sections pulled out of the transport sleeve. The transport sleeves arrive on the heating wheel 20, while the pipe sections in a conveying and turning device 54, which connects the unloading wheel 52 with a loading wheel 56, dsszueiner belongs to the second group of turntables, in turn the upper end of the with the closed bottom provided pipe section is heated and formed into a mouth profile will.

4-7 are details of the conveying and turning device 54 shown. In this device, the closed end of the pipe section turned down and the still open end goes up. For this purpose, the in Fig. 5 provided chain links 60 provided, which have laterally open compartments 62, into which the pipe sections 26 are used. In transport direction or in The individual chain links 60 are in the longitudinal direction of the conveyor chain by means of connecting bolts 64 rotatably connected to each other. The ends of the connecting bolts 64 are spherical Flanges 66 are provided in correspondingly shaped recesses of rings 68 are pivotably mounted. The flanges 66 are through with the connecting bolt 64 screwed nuts 70 and the rings 68 through a screwed to the chain link Disk 72 held. In this way, joints are provided which have a free Rotating the chain links 60 about the axis of the connecting pins 64 and also a allow limited pivotability of the chain links against each other.

The individual chain links 60 form an endless conveyor chain that placed around two deflection wheels 74 and 76 shown in FIG is. To guide the chain links in a vertical orientation, those shown in FIG. 6 are used Guide members 80, the input and output of the turning device 92 and on the opposite returning section of the conveyor chain are provided.

The guide members 80 consist of a plate 82 with a cutout 84, in which the chain links 60 run. The chain links with their Disks 72 drawn along guide rods 86, which the individual guide links 80 connect with each other. A turning of the chain links around the axis of their connecting pins 64 is avoided by further guide rods 88. Through the guide rods 88 the pipe sections are also secured against falling out of the compartments 62.

In Fig. 7, a guide member 90 of the turning device 92 is shown. Several guide links 90 are fixedly arranged one behind the other in the transport direction, as can be seen from FIG. 4, with each cutout 94 relative to the preceding Cutout is rotated by a certain angle. Overall, the angle of rotation is 180 °, so that the closed bottom of the pipe sections at the exit of the turning device 92 turned down. The chain links are thereby moved by means of their disks 72 carried on four guide rods 96 and guided on several guide rods 98.

After the pipe sections have been turned, they are inserted into the Entered the clamp gripper of the loading wheel 56, while inserting it into new transport sleeves and transferred to a second heating wheel 100.

The heating wheel 100 and another transfer station 102 are practical identical to the heating wheel 20 and the transfer station 38. On the heating wheel 100 is the upper open end of the pipe sections at forming temperature warmed up and then transferred from the transfer station 102 to a second forming wheel 104.

The forming tools of the forming wheel 104 are shown in more detail in FIG. 8. The pipe section 26 with a closed bottom is inserted in a transport sleeve 106, in the manner already shown in FIG. 2 on the not shown Forming wheel 104 is held. The contour of the opening 108 corresponds to the bottom shape of the Pipe section 26. In FIG. 8, the molding tool 110 is shown in the closed state. The molds consist of the two mold halves 112 and 114 of a mouth shape, are formed in the depressions 116, the upper heated end of the pipe section 26 give a profile such as is necessary for the application of a closure, e.g.

a screw cap is required. The two halves of the mold are held in the closed position by a locking bell 118.

A mandrel 120 with a conical one is used to expand the upper end Shoulder 122, in the central bore 124 of which a stretching mandrel 126 is displaceable, the end of which has a spherical head 128.

The mouth shape is in the input position at the transfer station 102 110 opened, the locking bell 118 being lifted upwards. In this The pipe section 26 is positioned in the transport sleeve 106 by means of its servo drive 130 raised up between the mold halves 112,114. Here are mandrels 120 and Reckdorn 126 still in their upper position, as in the right half of the Fig. 8 is shown.

When the mold halves 112, 114 are closed, the pneumatic Servomotor 132 is activated and the mandrel 120, which is also the locking bell 118 carries, moves downwards, with the cap first opening the mold halves encloses and then the mandrel penetrates into the upper heated fingers and with the conical shoulder 122 displaced material into the depressions 116 and thus the anchored in the upper part of the mouth area in the mold halves.

This position of the mandrel 120 is shown in the left half of FIG.

The stretching mandrel 126 is then moved by means of the pneumatic servomotor 134 drove down and lies down on the closed floor and presses the Transport sleeve 106 back to a stop, not shown, the Pipe section 26 is extended by connecting to the upper end outside the heated mouth area lying on the anchorage is drawn out thinly.

If the stretching mandrel 126 has its end position predetermined by the stop reached, a blown air valve, not shown, is opened and blown air flows through the channel formed between the stretching mandrel 126 and the forming mandrel 120 into the Pipe section 26 and presses the still warm material into the profile 116 of Mouth shape into it. The preform is thus completely shaped. After cooling down of the material, the molds are returned to their original position. The preform is finished and is transferred with the transport sleeve 106 to an unloading wheel 136 (FIG. 1).

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Claims (13)

Method for producing preforms from thermoplastic Plastic in which pipe sections are heated to the deformation temperature at both ends one end with the help of a support mandrel inserted into the pipe section and one hollow shape is formed into a closed bottom, and on the other End with the help of an external mold and a mandrel with a profile to put on a closure provided mouth is formed, the in transport sleeves vertically held preforms on turntables at the individual workstations are passed for heating and forming, characterized in that on one first group of turntables heated the upper end of the pipe sections and turned into one closed bottom is reshaped so that the preforms are then rotated by 1800 and that on a second group of turntables the opposite upper one The end of the preforms is heated and shaped into a mouth profile. 2. The method according to claim 1, characterized in that the of the axial forces exerted on the preform by the molding tools via the respective cold end of the preform are taken up by the transport sleeves. 3. The method according to claim 1 or 2, characterized in that in the second group of turntables that are located on the ones enclosed in the outer mold Section adjoining mouth area axially stretched by means of a stretching mandrel and is drawn out thinly, the closed bottom supported in the transport sleeve of the preform detected. 4. Device for performing the method according to one of the claims 1 to 3, characterized in that a first group of turntables from one Loading wheel (20), a heating wheel (30), a transfer station (38), a forming wheel (40) for forming the closed bottom and an unloading wheel (52) that one second group of turntables from a loading wheel (56), a heating wheel (100), a Transfer station (102), a forming wheel (104) for forming the mouth profile and an unloading wheel (136), and that between the unloading wheel (52) the first Group and the loading wheel (56) of the second group is provided with a turning device (54) see is. 5. Apparatus according to claim 4, characterized in that the turning device (54) is provided in the form of an endlessly revolving conveyor device. 6. Apparatus according to claim 4, characterized in that for circulation in the first group of turntables certain transport sleeves (24) and for circulation certain transport sleeves (106) are provided in the second group of turntables are. 7. Apparatus according to claim 6, characterized in that the transport sleeves (24,106) have openings for inserting preforms and on the forming wheels are arranged displaceable and supportable in the axial direction. 8. Device according to one of claims 4 to 7, characterized in that that several molding stations are provided on the molding wheel (40) of the first group, each consisting of a through a bore (46) in the transport sleeve (24) in the Insert the pipe section (26) into the support mandrel (44) and one onto the heated upper end of the pipe section attachable hollow shape (48) exist. 9. Device according to one of claims 4 to 8, characterized in that that several forming stations are provided on the forming wheel (104) of the second group, each enclosing the upper heated end of the preform (26) at one end Outer mold (110) and a mandrel (120) that can be inserted into the preform from above exist. 10.Vorrichtung according to claim 9, characterized in that a stretching mandrel (126) axially displaceable in a central bore (124) of the mandrel (120) is arranged, and that an actuating device (132,134) for the mandrel and the stretching mandrel is provided through which, after the outer mold (110) has been closed, first the forming mandrel and then the stretching mandrel are displaceably driven. I1.Vorrichtung according to any one of claims 4 to 10, characterized in that that the conveyor device (54) for turning the preforms the end a conveyor chain guided around two deflection wheels (74, 76) and perpendicular to it, their chain links (60) rotatably and articulated to one another in the transport direction and between the deflecting wheels on fixed, helically arranged guide members (90) are supported, the chain links having compartments (62) for inserting preforms exhibit. 12.Vorrichtung according to claim 11, characterized in that the chain links (60) are connected to one another with connecting bolts (64) which extend in the direction of transport extend and are hinged in the middle of the chain links. 13.Vorrichtung according to claim 11 or 12, characterized in that at the ends of the chain links (60) centered on the connecting pins (64) guide washers (72) are attached, which are rotatably supported in stationary guide rods (86,96) are.