JPH10193446A - Blow molder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To blow-mold a plurality of parisons simultaneously by guiding the parisons at narrower pitch independent from the pitch of molding cavities in a heating course at a re-heating system blow molder. SOLUTION: A heating course 1 and blowing course 7 include respectively conveying devices 2 and 10, both of which are guided about pulleys. At one sides of the respective conveying devices, heating means 6 and blow molds 8 are arranged. A transferring means 11, in which the conveying device 2 includes arms 4 receiving a parison at close pitch and projecting laterally so as to make the turning radius (r) of the conveying device 2 smaller than the turning radius of a mandrel 5 on the arm 4 so as to unload a plurality of parisons at one time from the heating course and transfer to the blowing course, is interposed between the conveying devices 2 and 10. The, when parions take the intervals corresponding to the intervals of blow molding cavities, the transfer means are controlled so as to grasp the parisons in order to place them in the blowing course.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the production of hollow plastic articles in a special form of blow molding process.
Here, a parison produced by an injection molding method is removed from a supply device, heated to a blow temperature in a heating path, and subsequently transferred to one or more blow molds. In the blow mold, the parison is blown by the mold cavity of the blow mold to form a hollow plastic article of a predetermined shape and size. Methods in which the cooled parison removed from the supply is reheated to the blow temperature have long been referred to as the "reheat method."

[0002]

BACKGROUND OF THE INVENTION Individual parisons span their entire length,
And, to be able to heat evenly to the blow temperature over their entire cross-section, and because the heat passes through the cross-section at a relatively slow rate, the parison will follow a long heating route along a straight or curved path. Mostly move. On the heating route, spaced heating units, usually infrared radiators, are aligned, and the portion of the path between the heating units is short enough for heat applied from outside the parison to pass through its cross-section. This is a so-called compensation or cooling section. In addition, these sections are to ensure that the outer wall of the parison is not overheated, such overheating often occurring with many plastics that are sensitive with respect to so-called process windows.

Such systems usually do not present any difficulty if only one parison is transferred to the blow mold at a time after passing through the heating path (eg EP 0 387 735 A1). In contrast, difficulties arise if multiple parisons are transferred to multiple blow molds arranged in a special blow path to increase power and increase the economic efficiency of the reheating system. That is,
The parisons should move along the heating path at relatively close pitches in order to efficiently receive the released heat, while the pitch of the blow mold cavity is the volume of the blown hollow article And the dimensions of the blow mold having their cavities and cooling channels. That is, while the parison must pass through the heating path at a relatively close pitch, the cavities of the blow mold must be accommodated in the blow path at a wider pitch than those pitches.

DE 31 30 129 A1 describes this problem and proposes a heating wheel as a solution. The heating wheel rotates between heating boxes fixedly arranged on the outer periphery at a close pitch to the parison, the holding mandrel that receives the parison, from which the parison is transferred to the blowwheel by a transfer wheel. The blow molds are arranged on the blow wheel at a pitch adapted to the dimensions of the blow mold.

[0005] The proposal made in DE 31 30 129 A1 can be transferred for the following reasons. That is, first, not each of the holding mandrels, for example, only the first, third, fifth, seventh mandrel, and then, after a full revolution of the heating wheel, the second, fourth, sixth , Because every eighth holding mandrel is provided with a parison from the supply device, and of course one parison is transferred to the blow mold only after two rotations. After two rotations,
The machine runs continuously as the parison is transferred to the blow mold on the blowwheel and the new parison is simultaneously placed in all positions on the heating wheel that has been freed for transfer to the blowwheel .

Since only the second parison is transferred from the heating wheel to the blow wheel in a continuous order, the pitch of the blow wheel can be twice as large as the pitch of the heating wheel. Of course, in this way, all of the parisons may pass through the heating path three times before being transferred to the blowwheel,
Of course, the pitch of the blow mold can also be selected.

[0007]

However, this method has, for example, the following disadvantages. That is, also in this system, only one blow mold with one cavity can be filled at a time with one parison, and also before the parison is removed from the heating wheel and transferred to the blow wheel. With the effect that the heating path consists of two equal parts, all the parisons have to pass over two revolutions of the heating wheel.

As a result, as far as the heating operation up to the blow temperature is concerned, during the second travel compared to the first travel,
There is no possibility that the heating conditions and the compensation and / or cooling section between the heating devices can be varied adaptively.

Furthermore, machines operating with this known system require more space to obtain the same output (output).

It is thus an object of the present invention to guide the parison at a close pitch in the heating path through the heating section and the intervening compensation and / or cooling section, while the blow mold or the blow mold in the blowing path. The pitch of the mold cavities is not only independent of the pitch of the parison in the heating path, but also one or more blow molds with a plurality of blow molds or a plurality of cavities in the blow path, the hollow plastic It is an object of the present invention to provide a reheat-type blow molding machine which enables simultaneous loading of parisons which can be blown simultaneously to form articles.

[0011]

In order to achieve the above object, one embodiment of the present invention is a blow molding machine for producing a hollow plastic article which operates according to a reheating method, wherein the blow molding machine comprises a blow molding machine. A heating path for heating the incorporated cold parison; after heating, the parison is transferred from the heating path to the blow path at a pitch corresponding to the spacing of the blow molding cavities and at a greater distance from the heating path than the heating path; The parison is introduced into one or more blow molds, blown to form a hollow plastic article of a desired shape, then cooled and removed from the blow mold to accommodate a new parison. In the blow molding machine constructed as above, the heating path and the blow path (1, 7) are provided with a turning device (3, 9).
A transport device (2, 10) for the parison, guided around a heating device (6) arranged on at least one side of the transport device (2) and of the transport device (10). At least one blow mold (8) is arranged on one side, the conveying device (2) of the heating path (1) includes an arm (4) for receiving the parison at a close pitch,
The arm (4) is laterally oriented such that the deflection radius (r) of the transfer device (2) is smaller than the deflection radius (R) of the mandrel-type receiving means on the arm (4). A transfer means (11) for removing a plurality of projecting and continuous parisons from the heating path at one time and transferring the parison to the blowing path includes a turning position of the heating path and a portion of the blowing path facing the turning position. Wherein the transfer means grips the parison when the parison takes an interval corresponding to the interval of the blow molding cavities in the blow path at the diverting position of the heating path. Characterized by being controlled to be placed in

In a preferred embodiment of the present invention, there is provided control means for moving the parison in the heating path (1) and the blowing path (7) in cycles each consisting of a forward and a stop period (V and S, respectively); Removal from the heating path, and transfer to the blow path,
A plurality of parisons are positioned equidistantly on the change path of the heating path, and occur during a stop period (S), where the transport device (10) is simultaneously in a stop period at a position where the parison is received on the blow path. It is characterized by the following.

A further preferred form of the invention comprises control means whereby all parisons are advanced by the same amount by the transport device (2) in each cycle of the heating path, but in each cycle of the blowing path. Only the number of parisons simultaneously transferred from the heating path to the blow path is advanced by the transfer device (10).

According to a further preferred aspect of the present invention, on both sides of the extension of the center plane (M) passing through the heating path, one of the respective transfer devices (10, 10a) and the transfer device (11) assigned to each. , 11a) are provided.

In a further preferred aspect of the present invention, the transfer devices (10, 10a) rotate in the same direction.

In a further preferred form of the invention, each of said transfer devices (11, 11a) is provided with a second parison prepared to be detached from said diverting portion at said diverting portion of said heating path (1). And the transfer device (10, 10) on the blow path (7, 7a).
a) The transfer is performed.

In a further preferred aspect of the present invention, the length of the arm (4) projecting laterally from the transfer device (2) of the heating path (1) and the holding mandrel ( The interval of 5) is determined by the distance of the molding cavity in the blow path (7, 7a).

The features of the invention and further structural features and advantages will be readily understood in light of the following description of a preferred embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which:

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 designates a heating path, on which an endless conveying device such as a chain 2 is stretched on deflecting pulleys 3, 3 'which rotate around an axis perpendicular to the plane of the drawing. Running. The chain 2 carries outward, i.e., laterally projecting, arms 4 (only some of which are shown). The end of the arm 4 is formed as a parison table, for example, in the form of a holding mandrel, and rotates during forward movement. Holding mandrel 5
In the example shown in the drawing, the arm 4 stands upright at the tip of the arm 4 with respect to the paper surface. The parison supplied from the supply device 1 ′ via the supply system 2 a can be attached to each of the holding mandrels 5.

[0020] 6,6 ', 6''... 6 n heating means arranged in relation spaced from each other along a heating path, for example, an infrared emitter, the radiation is mounted on a mandrel 5 Heat the parison from outside. The figure shows
Only heating means arranged along the sides of the transport device 2 are shown, but these means may be located next to the forward and return paths of the chain 2 in the figure.

Reference numeral 6a denotes a cooling device for blowing, for example, cooling air to the back surface (as viewed from the heating means) of the parison held by the mandrel 5.

Each heating path is associated with at least one blow path, generally indicated at 7, and in the example shown, a blow mold 8 'having four mold cavities.
And the blow molding means 8 is arranged on the blow path. The blow path 7 further includes a chain 10 rotating in the direction of the arrow around the deflecting chain wheels (pulleys) 9, 9 '. The blow-molded hollow plastic product is taken out from the position of the deflection pulley 9 '.

In the case of the illustrated machine, the heating path 1 operates in synchronization with the two blowing paths 7, 7a. In the blow path 7a, the same blow molding means 8a as the blow molding means 8 is provided.
And a deflection pulley 9a, 9a 'and a chain 10a running around them.

In the illustrated example, the first blow path 7
In the blow molding means 8 arranged in the second blow path 7a, the blow molding mold 8 'arranged in the second blow path 7a is closed. ″) Indicates an open state.

As shown in an enlarged manner in FIG. 2, the transfer devices 11 and 11a are located between the left end in the drawing of the heating path 1 and the start of the right side in the drawing of the blow paths 7 and 7a, that is, the heating device. It is interposed between the diverting pulley 3 of the path 1 and the diverting pulleys 9 and 9a of the blow path.

The transfer devices 11, 11a remove the parisons heated to the blow temperature from the deflection of the heating path in a controlled manner and remove them from the chain 1 of the blowing path 7.
0 or a mandrel (not shown) provided in the chains 10, 10a of the blow paths 7, 7a. As is well known, these mandrels are provided vertically on the link of the chain in the plane of FIG.

The transfer devices 11, 11a simultaneously hold a plurality of, for example, four, sets of parisons on the heating path, remove them from the holding mandrel 5, and remove them from the chain 10, 10a of the blow path. Rotate to place on the mandrel. To this end, the illustrated lever-shaped transfer device 11 may be provided with, for example, a gripper 12 that operates mechanically or pneumatically (negative pressure).

As shown in the figure, one transfer device, for example, the transfer device 11 has its gripper, for example, the gripper 1.
With 2,12 ', 12 ", 12"', several, for example, four parisons 13,13 ', 13 ",
The set of 13 '''is gripped when the parisons are equally spaced at the deflection positions on the deflection pulley 3 of the heating path 1. In this position, i.e. when the transport device 2 is deflected by the deflecting pulley 3, the pitch between the parisons 13 and their holding mandrels is respectively increased. This is because the radius r of the pulley 3, which is the deflection radius of the transfer device, is smaller than the radius R drawn by an arc passing through the center axis of the parison attached to the end of the arm 4. This means that the length of the arm 4 and hence the radius of the deflection of the parison are dimensioned, so that the distance between the parisons when reaching the removal position is equal to the pitch of the cavities of the blow mold. Number of parisons on arm 4 reach the diverting pulley and all
For example, as soon as four parisons occupy an angle equally divided by the center plane M of the diverting pulley 3 at one time, it means that the parisons are transferred from the heating path to the blow path.

The transporting device 2 is appropriately moved in the direction of the arrow.
Move periodically. That is, after each forward motion, it stops for a predetermined time. The advance and stop times in the heating path may be, for example, 0.2 seconds each.

In this way, the parison transfers the transfer device 11
Are removed from the transport device 2 in a separated relationship, and are transferred to the chain 10 of the blow path 7. That is, when the gripper 12 of the transfer device 11 grips the parison, the lever rises, the parison is removed from the holding mandrel 5, and the lever rotates clockwise in the figure until the parison is positioned on the mandrel of the chain 10. And
The lever is lowered to place the parison on the mandrel of chain 10. Thereafter, the lever is raised again, pivoted counterclockwise, and returned to its original position for gripping a new parison.
The parison spacing corresponds to the spacing of the molding cavities arranged side by side in one or more blow molds.

The transport device in the blow path, for example the chain 10, is also moved in a time-controlled manner, and when both transport devices 2, 10 are at the same time or almost simultaneously at a standstill, the parison is removed from the transport device 2. The data is transferred to the transport device 10. However, the advance and stop times of the chain 10 can be varied within certain limits.

Because they are independent of the time of advance and stop of the heating path, the cycle time of the blow molding, ie one or more parisons are supplied to the blow mold and the blow molded hollow It can be adapted to the time required to remove the plastic article. There is plenty of time for such operation. Because,
For example, after grabbing four parisons with advance and stop times of 0.2 seconds each, for the purpose of removal and for the rotation of the transfer device which requires a short but some time. For this reason, 1.6 seconds (advance time of 0.2 seconds × 4 + 0.0.times.) In the heating path until there are again four parisons to be gripped at the position of the diverting pulley 3.
This is because 2 seconds of stop time × 4 = 1.6 seconds) elapse.

This ratio is greater for gripping the parison if the heating path 1 operates for two blow paths 7, 7a, as shown, and for transferring and treating the parison in the blow path. It is further improved to be advantageous over long time intervals. For example, after the transfer device 11 transfers the parison to the chain 10,
This is because the next four parisons circulated to the deflecting position do not grab, but only the next four parisons. The next four parisons circulated above are the transfer device 1
1a to be moved to the blow path 7a.

Thus, in the illustrated embodiment, if the cycle consists of a forward time and a stop time,
The cycle ratio will be 4: 1. This means that four cycles elapse in the heating path and one cycle elapses in the blowing path.

This process is described with reference to the diagram of FIG. It is also assumed that the cycle is not absolute, but is divided into two equal length parts in the blow path, namely the advance time and the stop time. FIG.
As can be seen from FIG. 4, in heating path 1, four cycles consisting of forward (V) and stop (S)
Required to bring one parison to the position required to transfer it to the blow path. Here, the stopping of the transfer device 2 in the heating path 1 (S) and the chain 10
Stop (S ') means that both devices have a stop time at the same time, but it is important that the stop time of the chain 10 overlaps so that the stop time of the transport device 2 is as long as possible. During the downtime of the chain 10, the parisons already located on the heating path (four parisons in the case shown) are removed from the heating path and placed not only on the chain 10 but also on the opened blow. The four parisons located between the mold parts are gripped by the closed mold, blow molded, cooled, and then removed from the mold as a blow molded product. Even after the transfer device is raised, i.e. before the parison is placed in the transfer device 10 or 10a of the blow path 7, 7a, it is even possible to periodically move the transfer device 2 of the heating path 1 forward. It is possible. Shortly thereafter, the forward movement (V) of the four parisons takes place between or towards the blow mold halves opened by that time, and the timing cycle starts again.

In the straight section of the heating path, the parisons passing through the heating device are provided with a close pitch, and in the turning section, a large interval (pitch) corresponding to the pitch of the molding cavities in the blow path is provided. Can be
On the other hand, the parisons on the blow path differ in that their pitch remains unchanged. In the case of the heating path, the radius of deflection of the transport device 2 is smaller than the radius described by the parison on the arm 4,
On the other hand, in the blow path, the radius of deflection is
This is because it is the same as the radius described by the parison carried on zero.

As shown in FIG. 1, if one heating path functions for two blowing paths, the parison moves from heating path 1 to blowing path 7 during the stop period of the eighth cycle. Instead, the data is transferred only during the suspension period of the twelfth cycle. That is, the time available for forward movement and transfer of the parison to the molding cavity, blow molding and cooling operations is doubled.

As can be seen from the above, the system is very flexible. This is because, especially in the blow path, the cycle does not have to consist of the same length of advance and stop times. In order to have time to blow and cool the thick hollow plastic article in the blow mold, intervening a so-called immediate advance time between the two stop times, i.e. extending the stop time, For example, it is possible. It is of course also possible to extend the advance time, for example, to obtain a longer cooling or compensation time for the parison before it is transferred to the blow path and introduced into the blow mold.

As is generally known, the reheating method has certain difficulties in that the heat applied to the parison surface from the outside is distributed evenly to the inner wall through the entire cross section of the parison. However, this is quite easily achieved when there is sufficient time for the heat to propagate evenly through the cross section.

Furthermore, the machine according to the invention is flexible with regard to the number and arrangement of the blow molds and the dimensions of the molding cavities, especially when one heating path works for two blow paths. For example, of course, but within certain limits, from the same parison heated in the heating path,
It is possible to produce thick, small plastic hollow articles on the first blow path and correspondingly large, thin hollow plastic articles on the other second blow path.

[Brief description of the drawings]

1 is a plan view partially showing a blow molding machine according to the present invention, omitting some devices not related to the present invention, such as a transmission and a control cabinet;

FIG. 2 is an enlarged view of a part of FIG.

FIG. 3 is a diagram of a cycle time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating path 1 'Supply apparatus 2 Chain (transport apparatus) 3, 3' Deflection pulley 4 Arm 5 Holding mandrel 6, 6 ', 6 "... Heating means 6a Cooling means 7, 7a Blow path 8, 8a Blow molding means 8 ', 8a' blow molding die 9, 9 'deflection pulley 9a, 9a' deflection pulley 10, 10a chain 11, 11a transfer device 12 gripper 13 parison 13a blow molded product

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Franz Gittner Germany D-29574 Soltendi Quim Grundfeldt 33

Claims (7)

[Claims] 1. A blow molding machine which operates according to a reheating method and produces a hollow plastic article, comprising a heating path for heating a cold parison taken from a supply device, and after heating, the parison comprises the heating path. Are transferred to the blow path at a pitch greater than the heating path corresponding to the spacing of the blow molding cavities, where the parison is introduced into one or more blow molds and the hollow of the desired shape is formed. In a blow molding machine blown to form a plastic article, then cooled and removed from said blow mold to accommodate a new parison, said heating path and blow path (1,7) are varied. A transport device (2, 10) for said parison guided around a directional device (3, 9), said transport device Heating means on at least one side of 2) (6)
And at least a blow mold (8) is arranged on one side of the conveying means (10), and the conveying device (2) of the heating path (1) receives the parison at a close pitch. The arm (4) such that the deflection radius (r) of the transport device (2) is smaller than the deflection radius (R) of the mandrel-type receiving means on the arm (4). A transfer means (1) for projecting in a lateral direction and removing a plurality of consecutive parisons from the heating path at one time and transferring them to the blow path.
1) is interposed between a deflecting position of the heating path and a part of the blow path facing the deflecting position;
When the parison has an interval corresponding to the interval of the blow molding cavities in the blow path at the deflection position of the heating path, the parison is controlled to be grasped and placed on the blow path. Blow molding machine. 2. A control device for moving the parison in the heating path (1) and the blowing path (7) in a cycle comprising forward and stop periods (V and S, respectively). Removal and transfer to the blow path may be performed simultaneously at a position where the plurality of parisons are positioned equidistant to the change path of the heating path and the transport device (10) receives the parison on the blow path. The blow molding machine according to claim 1, wherein the blow molding machine occurs during a stop period (S) in the stop period. 3. A control means, whereby all parisons are advanced by the same amount by the transport device (2) in each cycle of the heating path, but in each cycle of the blowing path, 3. The blow molding machine according to claim 1, wherein only the number of parisons transferred simultaneously to the blow path are advanced by the transport device (10). 4. A transfer device (11, 11) assigned to one of the respective transport devices (10, 10a) on both sides of an extension of the center plane (M) passing through the heating path.
The blow molding machine according to claim 1, characterized in that two blow paths (7, 7a) each comprising one of (a) are provided. 5. The blow molding machine according to claim 1, wherein the conveying devices (10, 10a) rotate in the same direction. 6. Each of said transfer devices (11, 11a) receives a second set of parisons prepared to be removed from said diverting portion at said diverting portion of said heating path (1), The blow molding machine according to claim 1, 4 or 5, wherein the set is transferred to the transport device (10, 10a) on the blow path (7, 7a). 7. The length of the arm (4) projecting laterally from the transfer device (2) in the heating path (1) and the distance between the holding mandrel (5) from the transfer device (2). The blow molding machine according to claim 1, characterized in that it is determined by the distance of the molding cavity in the blow path (7, 7a).