DE10017529A1 - Sifting machine for extracting dust from new plastic granules and/or reground plastic material has a valve allowing excess reground material to be removed during sifting - Google Patents

Abstract

The sifter includes a dust extraction system, in particular one as claimed by Patent DE10004688.6. When large quantities of recycled sprue and runner regrind are to be combined with new material the correct ratio of the two is ensured by removing some of the recycled material from the material flow circuit at certain intervals. This is achieved through use of a valve(V8) below the sifter.

Description

The invention relates to a plastic granulate sifter with egg nem classifier for supplied granulate and / or regrind after the Patent application DE 100 04 688.6.

Today, plastics are used universally on a large scale sets, yet the future development potential is considered disproportionately forecast.

The granule sifter according to the invention can be used as a peripheral device used in plastic injection molding machines known per se become.

The material in these machines is in the form of granules processed. In addition to the molded part as an actual product usually also a so-called sprue occurs. From ecological For recycling reasons, it is advisable to recycle the sprue. H. to regranulate it using a mill and then to be added to the new goods. Grinding occurs next to the egg common regranulate also fine dust, which has problems tet and is therefore undesirable in itself.

Furthermore, material properties of the starting materials increasingly differentiated or improved. To do this impact substances such as B. glass fiber, heavy metals for example wise strength, color, temperature resistance and fire ver hold the finished product. The aforementioned If they are in the form of fine dust, substances are not just one Problem of cleanliness in operation, but can be hazardous to health  Effects on employees in the processing processing companies.

The previously known systems use simple suction conveyors. They transport the granulate or regrind to the spraying machine no The fine dust contained in the regrind does not become effectively withheld, but to a high degree in the work blown space or abandoned in the spraying process.

This problem is already addressed by the invention according to Pa tent registration DE 100 04 688.6 solved.

However, in the manufacture of molded plastic parts also a relatively high proportion of material occur, the recy must be celt. This occurs especially when ver equally small products with a large sprue len are.

However, it has been found that the recycled mate rial must not be added to the new goods in any quantity can, but at certain intervals completely or continuously must be eliminated from the circulation.

The invention is therefore based on the object of an art to specify material granulate sifters of the type mentioned at the beginning, the Sufficient quality with technically simple means ensures the plastic parts manufactured.

This task is performed on a plastic granulate sifter initially mentioned type solved according to the invention in that old sprue material can be discharged via a valve.  

One embodiment of the invention provides that the valve min at least to connect a level probe. This probe can a dead end, and / or another probe can be a silo be assigned. This valve is advantageously on lowest point of the classifier.

Furthermore, the valve is provided either manually or to operate automatically.

This ensures that the recycled material is not can be added to the new goods in any quantity, son change completely or continuously at certain intervals can be eliminated from the circulation.

According to an advantageous embodiment of the invention the granules and / or regrind in a reproducible ratio dosed into the classifier.

To keep transport routes between the To have plastic granulate sifter and the injection molding machine it is advantageous if a conveyor for feeding of the prepared mixture of granules and / or regrind the plastic injection and / or injection molding machine in the device is already in place.

Another embodiment of the invention provides that all functions of the plastic granulate classifier through the Un terdruck a central suction turbine are generated.

To simplify the supply of materials, the white teren be provided that different federation lines or channels are available which can be actuated by means of valves  are. These valves can have identical pinch valves his.

In order not to unnecessarily bind a worker who level of the classifier, it is advantageous in which Sifter to arrange a level limiter, so always at the supply is interrupted at a certain filling level can be.

A particularly advantageous dedusting is given if the vacuum cleaner has a fully integrated pre-separator has.

This pre-separator can be integrated into the extraction system the or as a separate component on granule dryer and Plastic injection molding machines are built. It can be advantageous fortunately from a combination of a special cyclone and an air classifier.

The selected modular design allows both v. G. Plant configuration rations. Thus, it can optimally meet the needs of the user To be received.

The pre-separator is closed on all sides, with the front a plastic glass pane is arranged. At the bottom te is a weight-operated Ver tailgate or a valve. The case is down conical on one or two sides. All pre-separators parts / parts in contact with the product are made of stainless steel. At the Four nozzles are attached to the housing, with automatic Valves are equipped.  

In addition, the separator is preferably horizontal Direction, a strainer basket insert (mesh size depending on Granules or degree of cleaning). This prevents the good the next filter stage.

It is possible to use the air required by the pre-separator to generate with a turbine.

Since it is quite possible that different amounts of air needed, it is advantageous if the turbine rotates is number controlled.

This can be done, for example, using device electronics be carried out, which also the other aggregates of dust can control sucker. It is therefore possible that all aggregates te of the vacuum cleaner with each other via this device electronics communicate.

Advantageously, the vacuum cleaner can also be self-cleaning gender vacuum cleaner.

The vacuum cleaner is new in this compact device so-called pre-separator is fully integrated. This advance Scheider is advantageously a combination of cyclone / Baffle plate separator on the one hand and a wind sifter on the other other.

The pre-separator is advantageous when a material is not conveyed has the desired dust content.

When extracting granules, the granulate sizes and spec specific densities on the one hand or the quantity and the procurement on the other hand, the nature of the dust varies greatly in practice.  In order to take this into account air is compressed at the inlet of the pre-separator blown in at high speed.

This air is generated by a speed-controlled turbine. This allows the air volume to be regulated and the optimal one Sighting set for the specific granulate material to be conveyed become. It is also possible that this blowing is pulsed is carried out.

The amount of air extracted or the amount of air blown in each of z. B. Turbines generated.

As stated above, the aggregates of art can granulate sifter and the vacuum cleaner via one device communicate with each other. It is also possible that they're directly from an operator of the processing machine can be operated from the control panel.

The additional function "bubbles" is mechanical and electrical in the Integrated compact device, that is, it is a complete system emerged.

It is also possible to blow the air yourself cleaning vacuum cleaner from a filter contained therein more to take. The suction speed in the turbine and the blowing air speed is in the ratio of 1: 1 to 1:10 to each other.

Further features and advantages of the invention result from the following description of several embodiments as well from the figures to which reference is made. Show it:  

Fig. 1 is a cross-sectional view according to a first exemplary embodiment;

Fig. 2 is a cross-sectional view according to a second example embodiment;

Fig. 3 is a schematic representation of the flow diagram of the granule classifier in a concrete current version, and

Fig. 4 shows a variant of the embodiment shown in Fig. 3.

First, reference is made to FIGS. 1 and 2.

As can be seen from FIG. 1, the vacuum cleaner has an inlet opening through which granules and dust enter. This mixture of granules and dust enters through an opening in the pre-separator, in which a classifier 1 and a baffle plate are arranged. At the lower end of the classifier 1 there is a flap which can be actuated by weight. So if a certain amount of granules has accumulated on this flap, this flap gives in and lets the granules fall into a space underneath, which can also be a granule dryer.

The remaining air can then enter a fine filter chamber in which a filter cartridge or a post-filter is arranged.

Due to the suction power of the turbine 3 for conveying granules and the turbine 4 for classifying, the contaminated air enters the cartridge 2 from the outside radially inwards in the fine filter chamber and is passed from the inside of the cartridge through a post filter stage. After the post-filter stage, sterile air then escapes to the outside.

With the help of this vacuum cleaner, it is then possible to also ge aspirate harmful substances and sterile air into the Dissipate environment.

The pre-separator consists of a combination of a cyclone / baffle plate separator and an air classifier or classifier 1 .

This pre-separator can then be switched on when a material to be conveyed has unwanted dust components. The granule sizes and the specific densities as well as the amount and the nature of the dust are very different in practice. In order to take this into account, compressed air is blown in at a high speed at the inlet of the pre-separator. This air is e.g. B. generated by a speed-controlled turbine 4 . This means that the air volume can be regulated and the optimal screening can be set for the specific granulate material to be conveyed.

It is also possible to enter the air pulsed.

As already stated, the amount of air sucked in or the amount of air blown in are each generated by turbines 3 or 4 .

The vacuum cleaner also has a device elector, not shown electronics, via which the aggregates of the vacuum cleaner coexist others can communicate. But these aggregates can also by an operator of the processing machine from the control panel be defined from.  

The invention is particularly advantageous in the case of plastic gra nulat promotion or in the grinding of recyclable Plastic parts and when entering these into this art spraying machines or in the pellet dryer concerned applicable.

The additional function "blowing" is mechanically and electrically in integrated into this vacuum cleaner compact device, that is, it is a complete system was created.

The blown air can, for example, from the fine filter chamber of a self-cleaning vacuum cleaner can be removed.

The suction speed in the turbine and the blowing speed The ratio is between 1: 1 and 1:10.

In the variant according to Fig. 2 valves are additionally provided with fol lowing functions:
Valve 5 rinsing / cleaning the strainer basket insert
Valve 6 sifting / whirling up granules or fine dust
Valve 7 Conveying fresh granules
Valve 8 Conveying regrind from the mill

Usually only one valve is open, all other valves are closed. Venil 5 and 6 or 7 and 8 are alternately opened or closed.

Valves 7 and 8 can be opened to each other as a percentage, ie you can mix fresh or regrind to a certain ratio. After a predefined quantity of fresh goods and regrind is in the pre-separator, valves 7 and 8 are closed. Now valve 6 is opened, the mixture is in the pre-separator, is intensely inflated or sighted and, on the other hand, homogeneously mixed.

After a certain time (depending on the granulate properties, including fine dust, GF additives, etc.) Ven valve 6 closes and valve 5 is opened; this blows the strainer basket freely.

This process (valves 5 and 6 ) is repeated until the Granu lat grinding mixture is free of its undesirable fine dust.

These fine dust particles are collected by filter stage 2 and released into the dust container.

The complete suction and cleaning cycle is now complete sen and the next batch can be sucked in etc. pp.

A preferred variant of the invention is the integration in a system according to FIG. 3. According to the flow diagram according to FIG. 3, system components are functionally structured as follows:

• A) conveying and dosing of granules and regrind in the Sifter in reproducible proportions,
• B) sifting the granulate-regrind mixture,
• C) dust collector,
• D) Promotion of the processed mixture to art cloth injection machine,  
• E) Cleaning the system parts.

The function of the individual components is described in more detail below explains:

I. Promotion and dosing of granules and regrind in the Sifter in reproducible proportions

• 1. 1.1 All functions of the system are generated by means of negative pressure through one and the same central suction turbine.
  Special pinch valves can be used so that the different delivery lines / channels can be opened quickly. All valves are identical in construction.
• 2. 1.2 First, it must be ensured that with each treatment new granulate is present in the classifier, therefore granulate is first conveyed via valve V4, and up to level S2 (new goods), what of a filling level limiter is ensured. Should this stand cannot be reached, the system goes into malfunction.
• 3. 1.3 When limit level S2 is reached, valve V4 closes and the valve V3 is opened. Only then will the meal well sucked into the sifter. Using the timer Quantity set.
• 4. 1.4 The respective flow rate during process 1.2 . and 1.3. can also be adjusted by changing the speed of the suction turbine.
• 5. 1.5 If the suction power is reduced during operations 1.2 . and 1.3. each very shortly before the respective cycle ends, so it is ensured that neither granules nor regrind are stored in the Ventilman sleeve during the closing process of the valves. The same applies when the valves are opened.

II. Sifting the granulate-regrind mixture

• 1. 2.1 The components granulate and regrind can each in a single suction into the sifter the. In previous suction conveyors, mixing was used che the ratio of granules or regrind during conveying change set. Despite pulsing switching between the two delivery lines are forced to one more or less high stratification of the individual compo elements in the conveyor's storage silo. This stratification does not occur with the new plastic granulate sifter.
• 2. 2.2 After closing the valves V3 and V4 (see I.) the material conveyance is finished. Then valve V2 is opened, through the now active bypass, air is sucked directly into the classifier at high speed.
  There are strong, turbulent flows on the individual components present, which are thereby swirled intensively with one another so that a homogeneous mixture is generated.
• 3. 2.3 A cylindrical sieve basket insert is installed horizontally in the classifier. During operation 2.2 . the fine dust mentioned at the outset is blown through this strainer basket insert and extracted directly into the dedusting system.
• 4. 2.4 The degree of dedusting of the aforementioned mixture is determined by the dwell time in the classifier or by the mesh width of the strainer basket insert.
• 5. 2.5 So that the strainer basket insert is not during the process blocked, it is released in a pulsed manner by means of valve V1 rinses or cleaned.

III. Dedusting system

• 1. 3.1. The double filter system used makes it practical "Sterile air" released into the work area. Highest number air quality requirements at the workplace thus fulfilled.
• 2. 3.2 The 1st filter stage is automatically cleaned in the cycle. The 2nd filter stage is normally used as a supply air filter, e.g. B. used in operating rooms, thus guarantees a maximum degree of separation.
  New in this context is also that in the actual cleaning process no particulate matter is pulsed backwards into the suction lines and thus indirectly into the working area. Mixing points do not prevent this pulsing, but tight-closing pinch valves completely prevent this process.
• 3. 3.3 It is also possible to use a suction turbine with brushless technology with variable speed control in the dedusting system. Suction conveyors use "brush runners" as standard. The service life of brushless turbines is comparatively 8-10 times longer.
  Maintenance and repair intervals are therefore drastically extended here. The points 3.2 . and 3.3. This ensures reduced maintenance, cleaning and repair work for the entire system.

IV. Promotion of the processed mixture to art fabric injection machine

• 1. 4.1 Valves V1 -V5 are closed to end process I. and II. Opening the valves V6 and V7 starts the conveyance of the mixture to the plastic injection machine.
  The granulate is now completely sucked out of the classifier into the machine silo.
• 2. 4.2 All steps I. and II. Are repeated as long as the level probe S1 reports demand in the machine silo. Then the entire system is ready for operation. If the probe requests material again after a certain time, the system is started and the preset number of cycles is repeated until the probe stops the material supply again.
  Referring to Fig. 4, a variant will now represents the reference to Fig. 3 described flow scheme Darge. The same reference characters are used for the same parts.
  This variant is followed by the following point:
• 3. 4.3 If a relatively high proportion of material has to be recycled, ie for comparatively small products and a large sprue, the recycled material cannot be added to the new goods in any quantity. It must therefore be completely or continuously eliminated from the circulation at certain intervals.
  This is done by opening a valve 8 attached to the bottom of the sieve, so that the no longer usable sprue material can be separated from the classifier.
  This can be completely or continuously eliminated from the circulation at certain intervals.
  The excreted sprue material can either be delivered to a sack port for regrind, the fill level of which can be determined by means of a fill level probe S3.
  However, it is also possible to introduce the excreted gate material into a silo for regrind, the fill level of which can be determined using a fill level probe S4.
  Otherwise, the conveyance of the prepared mixture to the plastic injection machine is identical to that described under points 4.1 and 4.2 .

V. Cleaning the system parts

• 1. 5.1 The system has an integrated vacuum cleaner outlet box. So you can do everything when changing products Clean the system parts thoroughly and quickly. The abge sucked particles are directly in the dedusting system promoted.
• 2. 5.2 When the suction hose is inserted into the socket, a make contact is inevitably actuated. This switches off all system components (V1-V7).
  The total suction power is therefore concentrated on the vacuum cleaner hose.

Claims (18)

1. Plastic granulate sifter with a sifter for supplied granules and / or regrind, with a dedusting system or a vacuum cleaner, in particular according to Pa tentanmeldung DE 100 04 688.6, characterized in that old gate material can be derived via a valve (V8). 2. Plastic granulate sifter according to claim 1, characterized ge indicates that the valve (V8) has at least one filling level probe (S3, S4) and the valve (V8) is located at the lowest point of the classifier. 3. Plastic granulate sifter according to claim 1 or 2, characterized characterized in that the valve (V7) manually or automa table is operable. 4. Plastic granulate sifter according to one of claims 1 to 3, characterized in that the granules and / or Regrind can be dosed in reproducible proportions or the regrind online from unwanted particulate matter len is exempted. 5. Plastic granulate sifter according to one of claims 1 to 4, characterized by a conveyor for feed tion of the processing mixture of granules and / or Regrind to a plastic injection and / or Spritzgußma Schine is. 6. Plastic granulate sifter according to one of claims 1 to 5, characterized in that all functions of the  Plastic granulate secure by means of a central Suction turbine generated negative pressure can be carried out. 7. Plastic granulate sifter according to one of claims 1 to 6, characterized by different delivery lines or channels that can be operated by means of valves. 8. plastic granulate sifter according to claim 7, characterized ge indicates that the valves have identical pinch valves are. 9. plastic granulate sifter according to at least one of the before standing claims 1 to 8, characterized by a Level limiter arranged in the classifier. 10. Plastic granulate sifter according to at least one of the above standing claims 1 to 9, characterized in that the vacuum cleaner has a fully integrated pre-separator has. 11. Plastic granulate sifter according to claim 10, characterized ge indicates that the pre-separator consists of a cyclone / Baffle plate separator and an air classifier. 12. Plastic granulate sifter according to claim 10 or 11, there characterized in that the need of the pre-separator air is generated by at least one turbine. 13. Plastic granulate sifter according to claim 12, characterized ge indicates that the at least one turbine speed controls is.   14. Plastic granulate sifter according to at least one of the above claims 1 to 13, characterized by a Device electronics. 15. Plastic granulate sifter according to claim 14, characterized ge indicates that the units of the vacuum cleaner over this device electronics communicate with each other. 16. Plastic granulate sifter according to at least one of the above arising claims 1 to 15, vacuum cleaner according to a of claims 1 to 6, characterized in that the Vacuum cleaner is a self-cleaning vacuum cleaner. 17. Plastic granulate sifter according to at least one of the above claims 1 to 16, characterized by a integrated vacuum cleaner junction box. 18. Plastic granulate sifter according to at least one of the above claims 1 to 17, characterized in that that a strainer basket insert is provided in the classifier exchanged or cleaned very quickly and easily and discontinuously from the system during the process can be blown or cleaned.