DE2444700C2 - Method for producing a container made of thermoplastic material with a stand ring molded onto the bottom of the container - Google Patents

Description

The invention relates to a method for producing a plastic made from thenoplastic Container with an integrally formed on the bottom of the container stand ring with the in the preamble of Claim 1 specified features.

The invention is based on a known method (DE-OS 14 54 915). at the one Kunststoffaß is made from a tube which is extruded into the center part of a blow mold and on both Ends of the bottom mold parts of the blow mold is detected, one of which has a blow pin. To After the pre-blowing, the bottom moldings are moved towards the middle part, one each for formation Stand ring the floor is concave, whereupon the final inflation takes place. With this procedure a targeted wall thickness distribution in the area of the floor and the footing is not possible. Also lets When the bottom moldings are retracted, the area of the base ring that is then to be molded on during blowing not determine exactly. Furthermore, by retracting the bottom moldings, only a relatively Form a flat, arched bottom that is directly attached to the side wall of the barrel.

It is also known (DE-AS 14 79 563), a tubular preform into a blow mold with an axially displaceable bottom mold part extrude and then inflate, in the area of the footprint of the standing ring to be formed an annular bead is formed. Then the bottom molding is moved axially inward, whereby the container bottom is inverted. The ring bead is formed into the mounting surface of the stand ring. Since the diameter of the side wall of the container must be larger than the diameter of the inverted container bottom, when the bottom molded part is retracted, an annular area results in which the pressurized molding is not supported.

This can give the stand ring an irregular shape or tear it open.

For blow molding of containers, it is also known (DE-OS 21 64 526), an extruded tube in one Pre-blow mold to pre-blow the preform into a preform similar to the shape of the final container to cool to orientation temperature in the pre-blow mold and then in a finished blow mold with axial and radial enlargement in the

ίο final shape to inflate, being a biaxial Orientation of the plastic takes place To axially stretch the preform, there is an axially displaceable one Floor molding provided. This known method is not aimed at the formation of standard

'5 from containers.

The invention is based on the object of blowing containers for pressurized liquids are suitable and have a stand ring on the convex or concave bottom.

This object is according to the invention by the cited in the characterizing part of claim 1

ιΞΠ ITiCTrCmSiC gCiGSi.

It is of considerable advantage to form the annular bead on the preform in the pre-blow mold. In order to the area is inevitably determined within which the inversion of the bottom part takes place The preform is then blown to completion in the final blow mold, so that the preform is in its base area completely from the bottom molding! the finished blow mold supported so that a concave or convex formed soil can be produced with a stand ring of great uniformity and strength.

In a further embodiment of the invention, the bottom of the preform can already be in the pre-blow mold be preformed by means of an axially displaceable bottom part. The precisely dimensioned training of the Base ring and the bottom is also done here in the finished blow mold, in which the bottom molding for a ensures complete support of the container bottom and the base ring.

A particularly advantageous development is achieved with the features of claim 3. Through this the strength of the base ring is increased significantly.

Protection is sought for the combination of the individual features specified in claim 1, however not for the measures known per se, an extruded tube in a special pre-blow mold to pre-blow or to form an annular bead on a preform.

Four exemplary embodiments of the subject matter of the invention are shown below with reference to the drawing explained. It shows

F i g. 1 shows a vertical longitudinal section of a device for pre-blowing a preform according to FIG first embodiment,

F i g. 2 to 4 show a longitudinal section of a blowing device for inflating the preform according to FIG. 1 into a Bottle,

F i g. 5 to 7 show a longitudinal section of a device for pre-blowing a preform according to the second Embodiment.

8 to 10 show a longitudinal section of a blowing device for inflating the preform according to FIG. 7 to a bottle,

11 to 13 show a longitudinal section of a blowing device for inflating a preform into a bottle according to the third embodiment,

14 to 16 show a longitudinal section of a device for pre-blowing a preform according to the fourth embodiment and

F i g. 17 to 20 a longitudinal section of a blower device for inflating the preform according to FIG. 16 a bottle.

A freely extruded, hanging tube (not shown) is surrounded by a pre-blow mold 60 with pre-mold halves 60 a, 60 b (FIG. 1). The pre-blow mold 60 has an annular groove 61 which is cut in the cavity defined by the preform halves 60a and 60ö. The groove 61 surrounds the cavity a little above the section of the cavity with which the convex bottom 63 of a tube produced by subsequent pre-blowing of the tube Preform 62 is determined. The preform 62 has an annular bulge 64 formed in the groove 61.

Next, the preform 62 is placed in a blow mold 65 (FIGS. 2 to 4), the two blow mold parts 65a and 65b of which can be opened and closed and together define a hollow mold 66 with open ends, the upper end of this hollow mold 66 being a has the opening 67 determining the closure and the lower end of the hollow mold 66 has an opening 68.

Separate plates 69a and 696, which are movable relative to one another, sit telescopically above the blow mold parts 65a and 65b , a base mold part 69 which, together with the blow mold parts 65a and 65b, are movable in the lateral direction for opening and closing. The plates 69a and 69 are also telescopically movable in the axial direction relative to the blow mold parts 65a, 65b when they are under the pressure of a blow head; 70 can be pushed down.

The blow head 70 has an axial air duct 71 and a lower conical section 72 and on Perimeter a shear edge 73, which is arranged above the section 72. When inserting the Blow head 70 in the opening 63 of the closed blow mold 65 give the surface of the section 72 and the Shear off 73 the upper end of the preform 62 the final shape of the container 76 to be manufactured.

Furthermore, during the downward stroke of the blow head 70, the blow molded parts 65a, 65> are brought into contact with the plates 69a, 69i>. A raised convex, the bottom 75 of the container 76 be.timmender portion 74, which is determined by the plates 69a, 696, touches the lower end of the preform 62 and bends the preform 62 upwards, so that the bottom 75 of the finished flaschei ^-t örmigen container 76 is obtained.

The arrangement of the annular bead 64 relative to the initial convex code 63 is such that this Annular bead 64 of double thickness surrounds the bottom 75 of the container 76 as a standing ring.

A preform 80 is produced in a pre-blow mold 81 with preform halves 81a and SIb, which together define a hollow shape 83 that is open at the top and bottom (FIGS. 5 to 7). The lower end of the hollow mold 83 is closed by separate base plates 84, which are supported on the preform halves 81a and 810 and join in their transverse movement, the base plates 84 squeezing the tube (not shown at the beginning) between them, creating a tail 85.

The bottom plates 84 can at the parison mold halves 81a and 81b for the preform SC are moved as shown by comparison of Figures 5 and 6 is apparent also in the axial direction relatively. The downward stroke of a blow head 86 is used after the initial inflation of the initially present blank inside the pre-blow mold 81 to push the pre-blow mold 81 telescopically downward over the fixed base plates 84.

From Fig. 5 it can be seen that the cross section of the preform 80, as it is formed at the beginning, ti its bottom 89 towards the junction of the bottom 101 of the finished container 100 and the side wall of the finished container 100 is reduced. Below this constriction 87 the widens Preform 80 extends conically to the outside as far as an annular bead 88, this conical shape merging into the convex bottom 89 of the preform 80, which tapers in the opposite direction is less than twice the wall thickness of the preform 80.

When the pre-blow mold 81 is displaced relative to the base plates 84, the base irj. The size of the displacement of the pre-blow mold 81 relative to the base plates 84 is designed so that the base 89 of the preform 80 is flush with the constriction 87, creating a smooth convex base 89 for the preform 80 is formed. Due to the contact between the still hot plasticized material of the base 89 and the same material at the constriction 87 under the pressure due to the relative movement of the pre-blow molded parts 81, the constriction 87 is welded to the base 89 in the immediate vicinity of the outer edges of the base plates 84.

In reality, the telescopic relative movement of the pre-blow mold 81 and of the base plates 84, the annular bead 88 is squeezed together, v / o by a conical section% doubled

Thickness is formed on the preform 80.

After the pre-blow molding, the preform 80 is placed in a blow mold 90, which consists of two mold halves 90a and 90b with an inner cavity 91 which defines the shape and size of the bottle-shaped container

100 (Fig. 8 to 10). Each mold half 90a, 90i has a base plate 92 which: to open and close together with the respective mold half 90a, 90b is movable in the lateral direction and can be displaced in the axial direction relative to its respective mold half 90a or 90b. Each base plate 92 is provided with an upper arcuate recess 93, these recesses 93 together forming the shape for the base 101 of the container 100. Furthermore, each base plate 92 has a semi-conical outer surface 94 on its side, this outer surface 94 interacting with the conical side surfaces 95 of the mold halves 90a, 90ό located below the cavity 91 and connected therewith. The side surfaces 95 receive the section 96 of the preform 80.

The shape and size of the cavity 91 of the blow mold 90 are such that the preform 80 inside the Cavity 91 rests on an annular lower lip 97 of the cavity 91, which is at the connection point of the cavity 91 with the side surfaces 95 arranged is

Thereafter, the blow head 70 is inserted into the open upper end of the preform 80, and the blow head

70 then presses the mold halves 90a, 906 downward relative to the base plates 92. This relative movement brings the recesses 93 of the base plates 92 between the mold halves 90a, 90i and the base plates 92 with the bottom 89 of the preform 80 in contact, the outer surfaces 94 of the bottom plates 92 with the Side surfaces 95 on the mold halves 90a and 906 cooperate to form the previously folded section 96 of the preform 80 to be pressed together to form a stand ring 99 (FIG. 9).

Thereafter, compressed air is used via the blow head 70 to inflate the preform 80 to the container 100 fed.

Due to the mechanical deformation and the pressurization of the previously crimped sections % results in a conical stand ring 99 with twice the thickness of essentially over its entire length is welded.

A preform 120 that was previously brought into this shape by inflating a tube (not shown) has a side wall 121, which has a convex bottom 122 over a foldable Connection portion 123 is connected (Fig. 11). Of the Connecting section 123 is connected to the side wall 121 via an annular bead 124 on the circumference, which extends located immediately below a conically outwardly inclined side wall section 125. the end The outer supporting wall 115 for the finished container 110 is formed later on this side wall section 125. The connecting section 123 becomes the inner support wall 113 in the case of the container 110 and is with the floor 122 connected via an inwardly protruding bead 126.

The preform 120 is inside two separable blow mold halves 127, 128 with an upper one the bottle closure determining opening 129 and a lower opening 130 suspended in the generally aligned with the annular bead 124 in the lateral direction. Furthermore, there are separate floor panels 131, 132 provided for each blow mold half 127, 128, the bottom plates 131, 132 in the lateral direction with the Blow mold halves 127, 128 are separable, but independently displaceable relative to these in the axial direction are. Each bottom plate 131, 132 has a concave top surface 133 for contact with the bottom 122 of the preform 120.

Outwardly and downwardly sloping semi-conical surfaces 134 are provided on each base plate 131, 132 for the Contact with the connecting portion 123 is provided, as well as generally parallel thereto, downwardly and outwardly sloping semi-conical sections 135 on each blow mold half 127,128 for one Contact with the sidewall portions 125 of the preform 120.

First, a blow head 136 is brought down into position to close the opening 129 and that To hold the upper end of the preform 120 relative to the mold halves 127, 128. Simultaneously with it die 136 reshapes the container closure in the same manner.

With a further downward movement of the blow head 136, the blow mold halves 127, 128 slide into the Floor plates 131 ,. 132 telescopically into it (Fig. 12). With such a telescopic movement the bottom 122 of the preform 120 pushed vertically upward, with the bead 126 the edges of the faces 133 of the base plates 131, 132 covered so that the surfaces 134 on the outside of the connecting portion 123 of the preform 120 attack. As well as the floor panels 131, 132 move relatively upwards, this abutment of the outer surface of the connecting portion 123 takes place on the surfaces 134, and the Sidewall portions 125 of preform 120 are outwardly in abutment with portions 135 of FIG Blow mold halves 127, 128 pressed. At the same time, compressed air is supplied via the blow head 136, whereby the Preform 120 is inflated.

In the first step in the production of a bottle-shaped container 139 according to the fourth exemplary embodiment, a hose 147 emerging from an extruder head 146 with an opening pointing downwards is cut off by means of a knife 148 (FIG. 14).
Before cutting, a pre-blow mold 150 for a preform 157 is brought into a position in which it encloses the tube 147 in which the preform halves 150a and 1506 of the pre-blow mold 150 are closed. The preform halves 150a and 1506 have two pinch-off elements 154 at their lower ends, which are opened and closed together with the preform halves 150a and 1506, but are movable relative thereto in the axial direction.
The preform halves 150a, 1506 form a hollow shape 151 for the preform 157, which has a shape lying between the shape of the tube 147 and that of the container 139. The hollow form 151 has a groove 152 running on the original circumference, which is arranged between the sections of the hollow form 151 which determine the side wall and the section 153 of the hollow form 151 which determines the bottom. As can be seen, the section 153 defining the bottom wall is convex, that is to say exactly in contrast to the concave shape of the bottom 142 of the container 139. When the preform halves 150a are closed. 1506, the hose 147 is squeezed off via the squeezing-off elements 154, the lower squeezed-off section 155 of the hose 147 lying completely outside the hollow shape 151.

In the next step, a blow head 156 is inserted into the cut open upper end of the tube 147 inserted and compressed air introduced into the interior of the hose 147 (Fig. 15). The hose 147 is thereby inflated to the preform 157, the circumferential an annular bead 158 surrounding the preform 157 having.

The preform 157 is then brought to a blow mold 160 which is made in the transverse direction openable and closable mold halves 160a and 1606 (Figs. 17 to 20).

Define the closed blow mold halves 160a, 1606 a cavity 162, the shape of which generally corresponds to the shape of the container 139 and with the upper end 161 and lower end 163 open. The mold halves 160a, 1606 are shorter than the preform 157, the end 163 of the Mold halves 160a, 1606 immediately next to the annular bulge 158 of the preform 157 and above the The bottom 159 of the preform 157 lies. Each mold half 160a, 1606 has a bottom plate 164, this being Bottom plates 164 for opening and closing with the mold halves 160a, 1606 are movable. Furthermore, the Bottom plates 164 in the vertical direction (axially to the preform 157) relative to the mold halves 160a, 1606 movable. In particular, the base plates 164 each have a spherical surface 165 which is centrally are arranged to the blow mold 160 and generally with the shape of the bottom 142 of the container 139 match and have a conical surface 169 in

a lower recess 166 for the end 163 of the associated mold halves 160a, 16Qb run out. A vertical guide surface 167 extends upward from the recess 166 on its outer side in order to provide a guide during a vertical displacement of the base plates 164 relative to the mold halves 160a, 160b .

A blow head 170 is inserted into the open end for inflation. of the preform 157 is used. Die 170 has its conical surface 171 which is inserted into the open end of the preform 157 and a ; auration 172 determining the closure of the bottle, which cooperates with the end 161 of the blow mold 160 to form the opening of the container 139. in the A duct 173 for compressed air is arranged in the blow head 170, with which the preform 157 to the container 139 is inflated (Fig. 18).

As shown in Fig. 18, the thrust of the Blow head 170 towards the end 161 of the blow mold 160 relative to the base plates 164 telescopically shifted downward, the end 163 of the mold halves 160a, 160Zj penetrating into the recesses 166. At a such telescopic movement, the surfaces 165 of the floor panels 164 contact the floor 159 of the preform 157 and bend the base 159 upward to the concave base 142. Through this Upward movement of the floor 159. The floor 159 actually folds over at the annular bead 158. In the telescopic movement touch the deepened at the lower ends d · - Blasfo'-mhälffin 160a, 1606 frustoconical wall sections 168 the outside of the preform 157 immediately above the

ίο annular bead 158, while the surfaces 169 directly on the Transition to the surface 165 at the bottom of the recess 166 is the outer surface of the bottom 159 of the Touch preform 157 immediately below the annular bead 158.

The wall sections 168 and the surfaces 169 are inclined slightly differently and approach one another when fully inserted, whereby the support wall sections 143, 145 are squeezed together and welded together,

2Q The material with darr, originally the Ringwuisi 15S of the preform 157 was formed, now forms the lower connecting portion 144 of a stand ring 174 of container 139.

In addition 6 sheets of drawings

Claims (3)

Patent claims: 1. A method for producing a container made of thermoplastic material with an integrally formed on the bottom of the container stand ring, in which a hose is extruded, the Hose pre-blown to a preform with a convex bottom, the bottom through an axial Moving a bottom molding arranged in a blow mold and inserted the preform is inflated in the blow mold to the container, characterized in that the pre-blowing of the preform takes place in a pre-blow mold and that at the same time on the shelf of the Stand ring associated area is formed an annular bead. 2. The method according to claim 1, characterized in that that in the pre-blow mold the bottom of the preform by means of an axially displaceable The bottom part is preformed. 3. worship according to one of claims 1 or 2 for the production of a container with a double-walled Stand ring, characterized in that the two walls of the by means of the bottom molding Stand ring are welded flat on top of one another.