DE2333943A1 - Pneumatic feed unit for powder or granules - maintains supply to several process hoppers by relating main feed rate to recycling rate of surplus - Google Patents

Abstract

A main storage unit supplies powder or granules to the feed hoppers of a number of process machines, e.g. injection moulding machines, via a pneumatically powered nozzle. Since the processes will not consume material necessary at the same rate, a return feed line is provided. The return material is fed to a compartment in a hopper. So long as sufficient material is fed back a flap closes off the supply from the main storage unit. Access to the main discharge hopper from collector is through two discharge openings.

Description

DR.1NQ. HANS LICHT! · DIPL.-INQ. HEINER LICHTI

PATENT LAWYERS

75 KARLSRUHE-DURLACH qRÖTZINQER STRASSE 61

TELEPHONE (0721) 41124

-3. JuH 1S73

June 22, 1973 2623/73

AZO machine factory Adolf Zimmermann, 696 Osterburken,

Rosenbergerstrasse 28

Pneumatic conveyor system for powder or granular

Good

The invention relates to a pneumatic conveyor system for loading one or more consumers with powdery or granular material from a storage container containing this with at least one supply line to the consumers and at least one line leading the unused return material to the storage container.

Such conveyor systems are used, for example, to supply plastic processing machines such as extruder screws or the like, used with plastic granules. The granules will

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separated from the conveying air flow by a separator assigned to each machine. The delivery rate, d. H. the specific material loading of the conveying flow is set so that all processing machines offer good will. To ensure this, you have to drive with an excess power. This as well as the fact the fact that one or the other consumer does not take off any good means that return goods are always transported back to the storage container will.

This return material is in the known systems again in fed into the reservoir. As a result, new goods and returned goods are mixed in the storage container. Since that Well, when it is transported through the plant, it is worn down and shredded and dust is formed as a result, changes the consistency of the goods supplied to consumers. This effect is particularly serious because the "useless" transport for certain parts of the container contents may take place several times, in particular with continuous operation of the plant. Another disadvantage here is that the full power is constantly applied must be, even if only some consumers take off good, which reduces the amount of returned goods and their unnecessary circulations is particularly large. This is not only because of the wear and tear of the goods, but also because of the plastic granulate in particular increasing static charge undesirable. Finally, the returned goods or parts thereof are below Under certain circumstances in the system for a much longer time, so that signs of aging also occur.

The invention is based on the object of designing a conveyor system of the structure described above so that the Return goods are fed to the consumers without unnecessary transport and the amount of return goods is reduced.

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According to a first feature of the invention, this object is achieved by a two-chamber container arranged downstream of the storage container, the first chamber of which is connected to the storage container and the return line in the second chamber opens, while at its outlet, which mainly receives the return material from the second chamber, the supply line connected.

The return material, the smallest amount of which corresponds to the excess capacity and the largest amount of which corresponds to the maximum conveying capacity - namely, if no consumer takes any more goods -, according to the invention, it does not return to the storage container, but in the second chamber of the two-chamber container. That transported from the supply line to the consumers Good is mainly taken from the second chamber, so that the returned goods are always first fed to processing. in particular, it is not mixed several times with the new material. As a rule, therefore, the return goods are forwarded have not participated in more than one transport cycle of its processing, so that its unfavorable change is kept to a minimum by wear and tear and aging, as is dust formation.

In order to ensure that primarily the returned goods from the two-chamber container and only secondarily the new material is removed, various embodiments are conceivable, the preferred being characterized by that the two-chamber holder has a partition which delimits the two chambers and extends from the outlet to the first chamber is offset towards and has a passage opening into the second channel.

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The outlet is thus practically assigned to the first chamber, so that the return material runs directly to it, while the new one Good in smaller quantities - as far as it can pass through the passage opening - reaches the outlet · Through appropriate The arrangement and design of the opening allows the proportion of the incoming new material to be roughly adjusted.

According to a further feature of this embodiment, the passage opening is with one of the return goods closable flap, which is preferably formed from a flexible disc attached to the partition. As long as return material is contained in the second chamber, this automatically closes the flap, so that no new one Well got to the outlet.

Instead of the described embodiment, the desired effect can also be achieved by appropriate Construction of the container and / or the partition and / or a possible passage opening the drainage speed of the returned goods is kept larger than that of the new goods.

While in the above-described embodiment of the conveyor system according to the invention, the disadvantages outlined above conventional systems can be avoided in that the return material first fed back to the consumers is before new material is fed into the system, these disadvantages can be according to a second essential feature of the invention by a pressure switch that switches off the conveyor fan, the contactor of which is set to approximately the one upon return the maximum pressure prevailing over the entire material fed in has been set, further reduce.

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The maximum pressure occurs when practically none of the consumers takes off any more goods and the entire load of goods of the flow rate occurs as return goods. While so far in continuous operation this good in the storage container arrives and new material is constantly fed into the system, the system is switched off according to the invention, as soon as consumers no longer buy anything or no longer buy a significant amount. So it is not unnecessarily transported good and tattered. The fan is conveniently switched on by a time relay. Herewith is created a very simple control, which can be done with level indicators to each consumer but with a lot more effort.

According to the invention, this control is further developed in that the two-chamber container feeds the material into the supply line feeding buffer container is arranged downstream, in which the outlet of the two-chamber container provided with a closing element opens, the closing element being actuated by a time relay actuated by the pressure monitor when the maximum pressure is reached is controlled.

As soon as the fan is switched off, a quantity determined by the timing relay enters the buffer tank and stops there on demand, whereby the fan can be switched on again by a time relay. This is running then until the maximum pressure is reached again. If necessary, the pressure switch can have several pressure shut-off stages have according to the respective performance or good requirements.

Further details and advantages of the invention emerge from the following description of a preferred embodiment

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management form of the conveyor system, which is indicated schematically in the drawing.

The conveyor system consists essentially of a good, z. B. plastic granulate containing storage container 1, a feed device 2, a blower 3 and a ring line formed from supply line 4 and return line 5. At this several consumers 6, z. B. extruder screws connected. The one to be filled via a line 8 The storage container releases the material via the feed device to the supply line 4, which has an injector-like effect Section 7 has. A separator is assigned to each consumer 6, in which the material is removed from the conveying flow as required of the consumer is deposited. The unused material is returned as return material via line 5 to the feeding device 2.

The feeding device 2 consists of a two-chamber container 20 and a buffer container designed as a pressure vessel The two-chamber container has a first chamber 21 and a second chamber 22 which are delimited by a partition 23 are. While the new material from the storage container 1 reaches the first chamber 21, the second chamber 22 is used for Acceptance of the returned goods. The return line is for this purpose 5 is introduced into the second chamber 22.

The two-chamber container 20 has one in the buffer container 30 discharging outlet 24, through which primarily the return material contained in the second chamber 22 runs off. In order to achieve this, in the illustrated embodiment, the partition 23 is from the outlet 24 to the first chamber moved there. The goods contained in the first chamber 21 can only be used after passing through a passage opening 25 in

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the partition 23 into the second chamber 22 and thus to the outlet 24. The passage opening 25 is also with a flexible flap 26 is provided, which under the action of the return material located in the second chamber 22 into the Closed position is pushed. This flap only moves into the open position when the pressure is exerted on it new material in the first chamber is greater than the resistance of the returned material. This is then the case when the second chamber 22 is almost empty.

The outlet 24 of the two-chamber container has an opening section 27 and is closed by means of a closure member 28 closable in the form of a cone, for which purpose a drive 29 is used.

A pressure monitor 31, for example in the pressure line 32 leading into the buffer container, is used for control leads to the good surface, is installed. As soon as the consumer 6 is no good or no significant amount If you lose more, practically all of the goods given up at 7 are returned to the two-chamber container as return goods 20. In this operating position, the pressure switch 31 sets the maximum pressure required to switch off the fan leads to avoid unnecessary material circulation. Since good is removed from the buffer container 30 for this transport cycle this must be refilled. The pressure monitor 31 therefore acts on a time relay, possibly with a delay 33, which switches on the drive 29 for a predetermined time. This moves the closing element 28 into the open position, so that first the return material from the chamber 22 and then, if necessary, new material from the Chamber 21 runs into the buffer container 30. After expiration

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After the set time, the drive 29 closes the closing element 28. If necessary, the conveyor fan can be used again at the same time 3 are switched on so that a new conveying cycle begins.

Lj / bl -9-

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Claims (6)

- 9 - 2623/73 patent claims 1. Pneumatic conveyor system for feeding one or more consumers with powdery or granular material from a storage container containing this with at least one supply line to the consumers and at least a line leading back the unused return material to the storage container, marked through a two-chamber container (20) arranged downstream of the storage container (1), the first chamber (21) of which is connected to the Reservoir is connected and in the second chamber (22) the return line (5) opens while on its outlet (24), which mainly receives the return material from the second chamber, is connected to the supply line (4) is. 2. Conveyor system according to claim 1, characterized in that the two-chamber container (20) has one of the two chambers (21, 22) has delimiting partition (23) which is offset from the outlet (24) to the first chamber (21) and has a passage opening (25) into the second chamber (22). 3. Conveyor system according to claim 2, characterized in that the passage opening (25) with one of the pending Return goods closable flap (26) is provided. -10-409884 / 0727 - 10 - 2623/73 4. Conveyor system according to claim 3, characterized in that the flap (26) consists of one attached to the partition (23), flexible disc is formed. 5. Conveyor system, in particular according to one of claims 1 to 4, characterized by a pressure monitor (31) which switches off the conveyor fan (3) and its contactor is set to approximately the maximum pressure prevailing when the entire material fed in is returned. 6. Conveyor system according to claim 5, characterized by a two-chamber container (20) downstream, the good in the supply line (4) feeding buffer tank (30), in which the one provided with a closure member (28) The outlet (24) of the two-chamber container (20) opens out, the closing element being provided by a pressure switch (31) when the maximum pressure is reached, the time relay (33) actuated is controlled. Lj / bl 409884/0727