DE212006000106U1 - Valve device for hollow blow molding machines - Google Patents

Abstract

Valve device for hollow-body blow molding machines for blowing compressed air via a blow cylinder (2) into a blowing volume with two different pressure levels (P1, P2), with a Vorblasventil (8), a Hauptblasventil (5) and a vent valve (6), wherein the Vorblasventil (8 ) are connected to a first pressure feed (P1) and the main blow valve (5) to a second pressure feed (P2), wherein the first pressure feed (P1) has a lower pressure level than the second pressure feed (P2), characterized in that the Vorblasventil ( 8) and the main blow valve (6) are arranged to act parallel to each other and the Vorblasventil (6) is designed as a multi-way valve, wherein the first input line (9) has a throttle (12) and acting against the feed direction check valve (13) and the second Input line (10) has a feed direction acting check valve (14), wherein the output line (11) with the output line (5 ') of Hauptbla sventils (5) and the input line (6 ') of the vent valve (6) is connected.

Description

The The present invention relates to a valve device according to the preamble of claim 1.

For the production of plastic bottles, in particular of PET bottles, becomes one Blank or preform in a blow molding machine in a blow cylinder usually inflated in two stages in its final form. For this purpose points the blank is already essentially the finished bottle head, which held in the blow mold of the blow molding machine and connected to a compressed air system. By blowing in compressed air through the bottle head, the blank is inflated and finally in his final Brought form.

Of the The actual blowing process is thus in a two-step process executed wherein first a Vorblasen with a pressure value between 4 to 20 bar over a Vorblasventil takes place, and then the finished blowing, d. H. the final forms the plastic bottle to its final shape, with a pressure value between 15 to 40 bar over a main blow valve takes place. These two valves are each with a pressure source connected to the corresponding pressure potential.

Subsequently at these two blow levels, the pressure from the plastic bottle and drained from the supply channels before the plastic bottle from the blow cylinder connected blow mold can be removed. This process step is also used as a vent designated.

These vent conventionally takes place via a Vent valve, which is connected to the blow cylinder and in open Position the compressed air into the environment.

There the pressure level and the amount of air for the blowing process by means of a Pressure generating means must be generated, means the blow this amount of air into the environment a correspondingly large energy loss.

It Now also devices and methods are known to at least to recover some of this residual air and as process air use.

For example Valve devices are known in which a partial recovery the compressed air over a separate valve, which between the blowing cylinder and the Vent valve arranged is, is realized. However, this additional valve must be separate be controlled and forms itself again additional dead space, which are filled must and its residual volume over the vent valve must be discharged into the environment.

In In this connection, it is noted that as dead space the lines and rooms included between the actual valves and the blowing cylinder of the channels be designated in the blow cylinder itself. The entire workspace consists of this dead space together with the volume of the hollow body, whose Content at the end of the blowing process to the ambient pressure; be adjusted got to. As filling volume is the amount of compressed air in the working space called.

The It is an object of the present invention to provide a valve device to find which in a simple way as much as possible of the filling volume recovers for further processes after completing the blowing process.

These Task is according to the invention achieved by a valve device with the features of claim 1. Further, invention embodiments arise from the features of further claims 2 to 8th.

The invention execution relates to a valve device for hollow blow molding machines for blowing from compressed air over a blow cylinder in a blowing volume with two different Pressure levels, with a pre-blowing valve, a main blowing valve and a vent valve, wherein the Vorblasventil with a first pressure feed and the main blow valve are connected to a second pressure feed, wherein the first Pressure supply has a lower pressure level than the second pressure supply. According to the invention For example, the pre-blow valve and the main blow valve are parallel to each other arranged acting and the Vorblasventil is designed as a multi-way valve, wherein the first input line a throttle and against the feed direction acting check valve and the second input line in the feed direction acting check valve wherein the output line is connected to the output line of the Main blow valve and the inlet line of the vent valve connected is. Thus, advantageously, the Vorblasventil both for the actual Vorblasprozess as well as for the recovery process be used, so that the dead volume for venting not by providing a additional A recovery valve elevated would have to be.

As a multi-way valve is here called a valve which a total of three connections in two possible valve resp. Has switching positions. In the present case, either the first or the second terminal, which are designed as an input, with the third terminal, which is designed as an output ver. By the two valve positions ver prevented. Such a valve is also referred to in the art as a 3/2-way valve.

When Valve is hereinafter referred to a shut-off valve, which two connections and has two valve positions. Doing so in the open Positions the two connections interconnected and in the closed position the two connections separated from each other.

For example are the inputs the two input lines of the Vorblasventils merged and connected to the first pressure feed. This will be during the Recovery process of Pressure from the hollow body and the dead spaces attributed to the first pressure feed, which is at a lower pressure level. Through the check valve in the second input line of the Vorblasventils is prevented that when the pressure drops within the hollow body and the dead spaces Compressed air from the first pressure feed flows into this area and thus get lost. Example catfish is just the entrance of the first input line of the Vorblasventils with the first pressure supply connected. This allows the compressed air to be flexible during the recovery process be fed to any other stage.

For example is the input of the second input line of the Vorblasventils with an intermediate stage of a pressure build-up device of the second pressure feed connected. Thus, the air is returned to the second pressure feed and for example, before the last compressor stage a buffer tank fed.

For example the Vorblasventil is designed such that in the rest position the second input line is connected to the output line, wherein the rest position is preferably set spring-loaded. In order to is the Vorblasventil in the rest position in the recovery position respectively. also in the venting position.

For example the main valve is closed at rest. Can not do that unintentionally high pressure in the system and in particular in the blowing cylinder be injected.

For example is the vent valve open at rest. This puts the system in the basic position pressure-free and in particular the blowing cylinder can not be unintentional be subjected to compressed air, resulting in accidents or damage to lead could.

For example flow the output lines of Vorblasventil and Hauptblasventil as well the inlet pipe of the bleeder valve in a common annular space of the blowing cylinder. So that can Valves are arranged arbitrarily with respect to the blowing cylinder and thus in particular short flow paths and small dead spaces will be realized.

The The object is further achieved according to the invention by a method.

At the present method for blowing arranged in a blow cylinder shaped hollow Blanks to a hollow body using compressed air, which in two different pressure levels is provided, wherein the first, lower pressure level over a Vorblasventil the blow cylinder is supplied and the second, higher pressure level over Main blowing valve is supplied to the blowing cylinder and after completion Blowing the pressure in the blowing cylinder and the hollow body over a vent valve discharged into the environment can be, according to the invention to Start of the blowing process, the vent valve closed. After that the Vorblasventil is opened, so that a first supply line the Vorblasventils over a throttle and a check valve is operatively connected to the blowing cylinder. After expiry of a predefined respectively. preset blowing time the main blow valve is opened, so that a supply line the main blow valve is directly connected to the blow cylinder. After expiration of a predefined resp. set main blowing time the main valve and the Vorblasventil are closed, whereby a second supply line the Vorblasventils over one opposite to the feed direction acting check valve is operatively connected to the blowing cylinder. Finally, after Sequence of a predefined resp. set recuperation time the vent valve open. By this method, a large part of the residual air is recovered and can be made available to the blowing process again. It has that has been shown to make savings in the delivery of Compressed air of up to 10% -25% can be realized. It is for the person skilled in the art that the Vorblaszeit and Hauptblaszeit accordingly the material properties of the hollow body and its shape chosen respectively. be set to work in as short a time as possible achieved an optimal shape and defined material properties become.

For example becomes the second supply line of the Vorblasventils with the first supply line of the Vorblasventils connected. This will be the recovered Residual air is returned directly to the first pressure level and is there directly to disposal.

For example, the second supply line of the Vorblasventils is connected to an intermediate stage of a pressure establishing device of the second pressure level. Thus, the recovered residual air is returned to the second pressure level. This can not be done directly because the residual air has a lower pressure level than the second pressure level, but by feeding into an already having a certain pressure preliminary stage of pressure generation, eg. As an intermediate stage of a compressor, a significant saving can also be achieved here. It has been shown that, for example, savings of up to 50% -70% can be achieved, depending on the pressure levels actually used at the two pressure levels.

For example is selected as the first pressure level, a pressure between 4 to 20 bar resp. set, d. H. a Vorblasdruck provided in this size.

For example is selected as the second pressure level, a pressure between 15 to 40 bar resp. set, d. H. provided a main blow pressure in this size, for example, by a multi-stage compressor system.

For example the recuperation time is determined by measuring the pressure in the blowing cylinder and reaching resp. Fall below a certain pressure value determined dynamically. This means that depending on the course of the Pressure reduction of the filling volume the vent valve when reaching resp. Fall below a certain pressure limit open becomes.

embodiments The present invention will be described below with reference to figures explained in more detail. It demonstrate

1 the working diagram of an inventive valve device for the inflation of plastic bottles;

2 schematically the pressure curve within the blast volume over the entire blowing process of a valve device according to the invention;

3 the working diagram of an alternative embodiment of an inventive valve device.

Out 1 the basic working diagram of an embodiment of a valve device according to the invention can be seen.

The hollow body 1 , For example, a bottle, starting from a blank (not shown), with a blow cylinder 2 is connected by blowing compressed air, for example in an annular channel 3 of the blowing cylinder 2 as well as with the support of one in the interior of the hollow body 1 introduced expanding mandrel 4 inflated to its desired shape.

For the supply of the blowing cylinder 2 With the compressed air necessary for this process, a valve device is now used, which provides the Vorblasdruck and the actual working pressure at the respective pressure level for a respective adjustable period of time. In particular, the size and duration of the Vorblasdrucks is very important for the blowing process, as a result, a correct distribution of material with the blowing cylinder 2 connected blank takes place.

For this is once the main blow valve 5 provided, which on the output side as a valve with the blowing cylinder 2 and the input side of the pressure supply P2 is connected. The main blow valve 5 is advantageously designed such that it is closed in the rest position, for example as a self-closing valve. The main blow valve can for example be electrically controlled directly, or else hydraulically resp. be controlled pneumatically via a pilot valve.

Next is also a vent valve as a valve 6 provided, which input side with the blowing cylinder 2 is connected and the output side, for example, a silencer 7 leads into the environment. The bleed valve 6 is designed to be advantageous open in its rest position. Thus, in the event of a defect, no build-up of pressure in the blowing cylinder 2 causes, but a possible over a wrong switched main valve 5 injected pressure directly via the vent valve 6 blown off to the environment, so that the blow cylinder 2 no potentially dangerous pressure conditions can arise.

According to the invention, the Vorblasventil 8th with two input lines 9 respectively. 10 and one with the blowing cylinder 2 connected output line 11 educated. In the first input line 9 is a throttle 12 and one in the direction of the input line 9 acting check valve 13 arranged and in the second input line 10 a non-return valve acting counter to the direction of the input line 14 , Im in 1 illustrated embodiment, the two input lines 9 and 10 merged and connected to the pressure supply P1.

The Vorblasventil 8th is designed such that it is in the rest position, the output line 11 with the second input line 10 operatively couples. When the Vorblasventil 8th activated resp. is opened, the output line becomes 11 with the first input line 9 connected. The control of the Vorblasventils 8th For example, can be done electrically, or via a pneumatically controlled pilot valve, which is controlled by the pilot pressure PP.

By this arrangement, the in 2 realize illustrated blowing curve. Below the pressure curve along the time axis T are the valve movements of the vent valve 6 (EXH), the main blower valve 5 (P2) and the Vorblasventils 8th (P1). In the example shown, a pre-blowing pressure P1 of 10 bar and a main blowing pressure P2 of 40 bar are used. In the pre-blowing phase, the pre-blowing pressure P1 becomes after opening the Vorblasventils 8th reached and held until the end of Vorblaszeit Tv. Thereafter, by opening the main blow valve 5 the working pressure reaches P2 of about 40 and held until the end of the main blowing time Th. At the end of this main blowing phase will be both main blowing valve 5 as well as Vorblasventil 8th closed, causing a pressure reduction in the blow cylinder 2 over the input line 10 the Vorblasventils 8th leads.

Im after 1 illustrated embodiment, the pressure is guided back into the pressure supply P1. Through the check valve 14 This feedback is then prevented at the latest when the residual pressure in the blow cylinder 2 falls within the range of Vorblasdruckes P1.

The check valve 14 prevents pre-blowing pressure in the blowing cylinder 2 can get.

As soon as the recuperation time Tr, the vent valve 6 is opened, that is brought into hibernation, the pressure falls in the blowing cylinder 2 and thus in the hollow body 1 quickly to ambient pressure. However, only the remaining amount of residual air is released to the environment.

A major advantage of this arrangement is the fact that by the summary of the valve functions for the actual pre-blowing and recovering in Vorblasventil 8th additional dead space is avoided, as occurs in conventional devices with a separate recovery valve. Thus, in view of the high pressure values and the generally high production volume, a not inconsiderable saving in compressed air can advantageously be achieved.

In 3 the scheme of an alternative embodiment of an inventive device is shown. The scheme is virtually identical to the scheme after 1 except for the formation of the two supply lines 9 respectively. 10 the Vorblasventils 8th , In the embodiment according to 3 are these two supply lines 9 respectively. 10 not merged, but is the second supply line 10 equipped with its own, separate entrance. This makes it possible to supply the recovered compressed air to any process. This can be advantageous, for example, an intermediate stage of a compressor stage, which the compressed air. P2 provides. This intermediate stage is not yet at the level of the main blow pressure P2, so that the recovered compressed air can be introduced there. It has been shown that significant savings in compressed air generation can be achieved.

Next the repatriation of the Of course, it can also supply compressed air to the compressor stage of P2 to other consumers of the blow molding machine or other Supplied to consumers become.

Claims (8)

Valve device for hollow-body blow molding machines for blowing in compressed air via a blowing cylinder ( 2 ) in a blowing volume with two different pressure levels (P1, P2), with a Vorblasventil ( 8th ), a main blow valve ( 5 ) and a vent valve ( 6 ), wherein the Vorblasventil ( 8th ) with a first pressure feed (P1) and the main blow valve ( 5 ) are connected to a second pressure feed (P2), wherein the first pressure feed (P1) has a lower pressure level than the second pressure feed (P2), characterized in that the Vorblasventil ( 8th ) and the main blow valve ( 6 ) are arranged parallel to each other and the Vorblasventil ( 6 ) is designed as a multi-way valve, wherein the first input line ( 9 ) a throttle ( 12 ) and acting against the feed direction check valve ( 13 ) and the second input line ( 10 ) a check directional check valve ( 14 ), the output line ( 11 ) with the output line ( 5 ' ) of the main blowing valve ( 5 ) and the input line ( 6 ' ) of the venting valve ( 6 ) connected is. Valve device according to claim 1, characterized in that the inputs of the two input lines ( 9 ; 10 ) of the Vorblasventils ( 8th ) and are connected to the first pressure feed (P1). Valve device according to claim 1, characterized in that only the input of the first input line ( 9 ) of the Vorblasventils ( 8th ) is connected to the first pressure feed (P1). Valve device according to claim 3, characterized in that the input of the second input line ( 10 ) of the Vorblasventils ( 8th ) is connected to an intermediate stage of a pressure build-up device of the second pressure feed (P2). Valve device according to one of claims 1 to 4, characterized in that the Vorblasventil ( 8th ) is configured such that in the rest position, the second input line ( 10 ) with the output line ( 11 ), wherein the rest position is preferably set spring-loaded. Valve device according to one of claims 1 to 5, characterized in that the main valve ( 5 ) is closed at rest. Valve device according to one of claims 1 to 6, characterized in that the vent valve ( 6 ) is open at rest. Valve device according to one of claims 1 to 7, characterized in that the output lines ( 11 ; 5 ' ) of Vorblasventil ( 8th ) and main blow valve ( 5 ) as well as the input line ( 6 ' ) of the venting valve ( 6 ) into a common annulus ( 3 ) of the blowing cylinder ( 2 ).