DE202017106256U1 - Device for conveying pasty media - Google Patents

Abstract

Apparatus for conveying pasty media from at least two containers (9), comprising at least one scoop pump (2) which is connected to a follower plate (3), wherein the scoop pump (2) is operated by means of a drive (4) and between scoop piston pump (2) and drive (4) a clutch (5) is arranged, characterized in that the drive (4) of at least one servo-pneumatically controlled drive cylinder (41) is formed, which is provided with an electronic distance measurement.

Description

The invention relates to a device for conveying pasty media from at least two containers, comprising at least one pump piston, which is in communication with a follower plate, wherein the scoop pump is operated by a drive and a coupling is arranged between the pump piston and drive.

Devices of the type mentioned are used for conveying, dosing and / or mixing of viscous material, such as plastic raw materials from a barrel-like container - the container -, for example, to a screw conveyor of a plastic injection molding machine, especially for so-called. "Liquid Silicone Rubber "(LSR) or liquid silicone rubber injection molding. This material is a low-viscosity, hot-vulcanizing two-component silicone, which is supplied ready-to-use by the material supplier in 20-liter or 200-liter container units A and B. The two addition-crosslinking components are fed under pressure to a mixing block with a multicomponent mixing and dosing system. The hitherto separately conveyed material is mixed in this unit in the ratio 1: 1 and fed to the screw conveyor.

When conveying the medium, the container is closed at the top by a follower plate, which follows the decreasing in the course of the conveying process material level in the container down and thereby sealingly rests against the inner surface of the container wall. The follower plate has an opening in the middle through which material can escape. The follower plate rests on the material and acts on it with a low pressure. The scoop pump conveys the viscous material through the opening from the container.

The dosage of the known devices, for example via double-acting metering pumps. In these, the metering takes place at each stroke, that is, regardless of which direction the pump piston moves. A disadvantage has proven to be that the piston during the dosage of on - switches to the downstroke - and vice versa. In this case, a brief pressure drop occurs. In addition, the switching leads to a short-term undefined material delivery, which negatively influences the dosing result.

In order to avoid the disadvantages mentioned, solutions are known in which screws or rotary lobe pumps are used. These pumps or screws are operated servo-electrically and are therefore expensive. In addition, they have further negative properties, such as, for example, a slip, which is viscosity-dependent and can only be compensated by downstream expensive measuring and control devices.

Against this background, it is an object of the present invention to provide a device for conveying pasty media, which on the one hand has very precise conveying properties and on the other hand is inexpensive in relation to the known devices. According to the invention, this object is achieved in that the drive is formed by at least one servo-pneumatically controlled drive cylinder, which is provided with an electronic distance measurement.

With the invention, a device for conveying pasty media is created, on the one hand has very accurate conveying properties and on the other hand is inexpensive in relation to the known devices. The electronic distance measurement allows extremely precise monitoring of the drive cylinder, so that an error message can occur with the slightest deviations from the preset path lengths. At the same time, the conveyed quantity of pasty media can be precisely determined by measuring the distance.

In a further development of the invention, the drive of exactly two servo-pneumatically controlled and single-acting drive cylinder is formed. This allows the precision, which is made possible by the use of the servo-pneumatic controlled and single-acting drive cylinder, transferred to both containers.

Preferably, the scoop pump is single acting. Due to the systemic only one-sided effect of the piston pump, they must be refilled after each metering stroke before it can be re-dosed, resulting in increased dosing accuracy. In addition, the occurring by switching pressure drop and the associated short-term undefined material handling are avoided.

Other developments and refinements of the invention are specified in the remaining subclaims. An embodiment of the invention is illustrated in the drawings and will be described in detail below. Show it:

1 the perspective view of a device for conveying pasty media;

2 a longitudinal section through a pump piston pump and

3 the schematic representation of the promotion of pasty media from the container to screw conveyor.

The device selected as an embodiment for conveying pasty media consists essentially of a frame 1 , It comprises at least one piston pump 2 that with a follower plate 3 communicates with the scoop pump 2 by means of a drive 4 is operated. Between pump piston 2 and drive 4 is a clutch 5 arranged. The piston pump 2 stands with a mixing chamber 6 in connection, via a shut-off valve 7 features. The mixing chamber 6 flows into an extruder 8th , The pasty media are in containers 9 ,

The piston pump 2 has a piston 11 in the top of a dosing cylinder 12 is guided. The piston 11 is in the dosing cylinder top 12 fixed. In the dosing cylinder upper part 12 is a guide bush 14 provided in which a leader tape 15 is arranged.

The dosing cylinder upper part 12 is with a Dosierzylinder lower part 16 screwed, with upper part and lower part by means of an O-ring 17 sealed. In the transition between the upper part and lower part is a check valve 18 arranged with an O-ring, which by a piston guide belt 19 is surrounded.

At the the follower plate 3 facing the end of the piston 11 In the exemplary embodiment, a two-part scoop plate is provided, which consists of a floating plate 22 and a perforated scoop plate 23 consists. For sealing the dosing cylinder lower part 16 against the follower plate 3 is an O-ring 24 intended.

On the dosing cylinder upper part 12 is an outlet 25 screwed on, the over a sealing ring 261 is sealed. In the outlet 25 is a check valve 26 arranged. Between the check valves 18 and 26 a space is formed for the pasty medium, which absorbs the amount of medium to be conveyed. With the outlet 25 is an elbow union 27 screwed. On the outlet 25 opposite side is on the Dosierzylinder top 12 an exit 28 mounted for venting, at its end facing away from the upper part of a ball valve 29 having. Between exit 28 and ball valve 29 is a sealing ring 30 made of aluminum. Inside the dosing cylinder top 12 is in the range of outlet 25 and exit 28 a V-ring 20 arranged.

The follower plate 3 is formed in a conventional manner. In functional condition, it is in a container 9 , About a sealing ring 31 is the follower plate 3 against the container 9 sealed so that the container 9 is closed. During conveying follows the follower plate 3 the decreasing level in the container 9 so the follower plate 3 deeper and deeper into the container 9 retracts.

The drive 4 is according to the invention of a servo-pneumatically controlled drive cylinder 41 educated. In the embodiment are accordingly 3 two servo-pneumatically controlled drive cylinders 41 intended. Also recognizable are two scoop pumps 2 shown, each in a container 9 protrude. The containers 9 are filled with various pasty media, wherein the medium marked "A" contains a catalyst, that the medium labeled "B" contains a crosslinker.

The piston pump 2 is designed to be simple. It is therefore promoted only in one direction medium. During one of the respective drive cylinder 41 triggered downstroke, where the piston 11 in the direction of the container 9 is moved, the scoop moves 23 in the Dosierzylinderunterteil 16 in the direction of the container 9 , During this process lifts the floating plate 22 from the scoop plate 23 from. This will be in the scoop plate 23 provided holes are released so that pasty medium through the holes in the Dosierzylinderunterteil 16 can occur. After completion of the stroke, the piston stops 11 on, so the swim plate 22 with the scoop plate 23 comes to rest, so that the holes are closed again. The drive cylinder 41 then moves briefly in the opposite direction, so that in the Dosierzylinderunterteil 16 located pasty medium is compressed.

About a - not shown - control, which may be, for example, a PLC control, the work of the extruder and the downstream plastic injection machine is monitored at the same time. Once the plastic injection machine has ejected the last-made plastic part after it has hardened and the injection mold is closed again, the extruder begins to convey the plastic injection material located in it into the plastic injection molding machine. As soon as this process begins, the drive cylinder moves 41 in the from the container 9 opposite direction, causing the piston 11 also in the container 9 turns away. At the same time medium with the help of the two-part Schöpfellers from the Dosierzylinderunterteil 16 through the check valve 18 in the direction of the mixing chamber 6 promoted. This will be in the between the check valve 18 and the check valve 26 trained space located medium through the check valve 26 in the direction of the shut-off valve 7 or the mixing chamber 6 pushed out of the room. In the mixing chamber 6 The components A and B pushed out of these spaces come together and react there to form a uniform mixture which is suitable for producing the respective plastic parts. After completion of the stroke of the piston 11 can excess, remaining medium in Dosierzylinderunterteil 16 over the gap between the top plate and the cylinder wall towards the container 9 flow away. The excess of the medium results from the fact that the volume of space between the check valves 18 and 26 smaller than the volume of the Dosierzylinderunterteils 16 ,

Due to the principle of the single-acting piston pump 2 is a very accurate dosage possible. After each filling process, the medium in the Dosierzylinderunterteil 16 precompressed and brought into a defined starting situation. In this way, a different degree of filling of the components A and B can be compensated from the containers. This ensures that the quantities required for optimum mixing of the two media are always conveyed in the direction of the extruder.

The drive cylinder 41 is provided according to the invention with an electronic path measurement. The electronic distance measurement allows a precise monitoring of the work of the cylinder and thus equally the conveyed amounts of pasty medium.

With the device according to the invention for conveying pasty media, extremely precise delivery of the medium is possible. At the same time a cost-effective conveyor device is provided which dispenses with complex servo-electric or other solutions.

Claims (4)

Device for conveying pasty media from at least two containers ( 9 ), comprising at least one piston pump ( 2 ) with a follower plate ( 3 ), wherein the piston pump ( 2 ) by means of a drive ( 4 ) and between pump piston ( 2 ) and drive ( 4 ) a coupling ( 5 ), characterized in that the drive ( 4 ) of at least one servo-pneumatically controlled drive cylinder ( 41 ) is formed, which is provided with an electronic path measurement. Device according to claim 1, characterized in that the drive ( 4 ) of exactly two servo-pneumatically controlled drive cylinders ( 41 ) is formed. Apparatus according to claim 1 or 2, characterized in that the scoop piston pump ( 2 ) is single acting. Liquid silicone rubber injection molding machine with an injection molding machine comprising an extruder ( 8th ) and a mixing chamber ( 6 ), comprising a device for conveying pasty media according to one of claims 1 to 3.

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