LUBRICATED MIXING DEVICE FOR REACTION PLASTICS AND METHOD FOR GENERATING REACTION PLASTICS

Abstract

A mixing device (100) for generating reaction plastic, the mixing device (100) comprising: a) a mixing chamber (110) for mixing reactive components to generate the reaction plastic; b) a discharge unit (120) connected to the mixing chamber (110) for discharging the reaction plastic generated in the mixing chamber (110); c) a cleaning piston (130) axially aligned with a discharge pipe of the discharge unit (120) and movable towards the discharge pipe to clean the reaction plastic from the discharge pipe;d) a fluid supply device for providing a lubricant in the discharge unit (120) through an outlet (142), for the purpose of lubricating the discharge unit (120), wherein i) the fluid supply device is configured to lubricate the movement of the cleaning piston (130) in the discharge pipe, wherein ii) the fluid supply device comprises a gas supply device (140) for providing gas together with the lubricant through the outlet (142) to the discharge unit (120), e) a control piston (115) positioned within the mixing chamber (110) for controlling the flows of the reactive components; wherein i) an axial direction of the control piston (115) is oblique, preferably perpendicular, to an axial direction of a discharge pipe of the discharge unit (120). A method for generating reaction plastic 2 is also described.

Description

DETAILED DESCRIPTION OF THE INVENTION The following description refers to a 100 mixing device for reaction plastics, configured as an L-shaped mixing head. It should be understood that this is not intended to be exhaustive. The principles described above could also be applied to any other type of mixing device. In particular, although all the figures relate to an L-shaped mixing head containing a discharge pipe and a cleaning piston, the operation of the fluid supply device, as described above, can be used for any type of mixing head, including linear mixing heads that do not contain a cleaning piston. Furthermore, although a specific example of a fluid delivery device comprising a gas delivery device and a lubrication device is given below, this is not intended to be limiting. In principle, any arrangement is possible that allows fluid lubricant, i.e., gaseous or liquid, to be fed directly through an outlet to components of the mixing device that are passed through reaction plastic mixed within the mixing device. The term “directly” here means that the lubricant enters this discharge unit without being fed through other parts of the mixing device, such as, for example, a glass bell jar or a space between a cleaning piston and a discharge pipe. The mixing device 100, shown in Figs. 1 to 4, comprises a mixing chamber 110 in which different components of a reaction plastic are mixed in a controlled manner to generate the reaction plastic. The reaction plastic could be a polyurethane foam, PUR, produced by mixing polyols and isocyanates together. However, it should be understood that any other reaction plastic consisting of an arbitrary number of components and additives could also be mixed in the mixing chamber 110. The mixing process carried out in the mixing chamber 110 is, in principle, well known to a person skilled in the art. Therefore, it is not necessary to discuss the structure and operating process of the mixing chamber 110 in detail. For example, the mixing could be carried out in a known manner, using a control piston 115 in which grooves are provided for a controlled supply of the reaction plastic components. For example, the mixing chamber 110 could be structured as described in DE 10 2015 112 445 A1. cwQcnn / zznz / E / Y The generated reaction plastic is discharged through a discharge unit 120, i.e., one or more components that are passed through the reaction plastic before being discharged from the mixing device 100. The discharge unit 120 may comprise at least one discharge pipe, as illustrated in the figures. However, the interior of the mixing chamber or adjacent downstream regions of the mixing device 100 may also be part of the discharge unit 120, even without a discharge pipe. Therefore, any part that comes into contact with the reaction plastic during its discharge may be considered part of the discharge unit 120. In the following description, the discharge unit 120 is assumed to comprise a discharge pipe. The discharge pipe of the discharge unit 120 may be provided at an oblique angle, preferably orthogonal, to the axial extension of the mixing chamber 110 and the control piston 115. The mixed reaction plastic is discharged through the discharge pipe. The arrangement, structure, and dimensions of the discharge unit 120 and the discharge pipe are well known to a person skilled in the art and do not need to be described in detail here. The discharge unit 120 may have any shape suitable for discharging reaction plastic. Due to the oblique angle between the mixing chamber 110 and the discharge pipe, the reaction plastic components will be further mixed when transferred from the mixing chamber 100 to the discharge pipe. Furthermore, this transfer will result in a laminar flow of reaction plastic. This allows for greater elongation of a nozzle attached to the discharge pipe compared to linear mixing. Consequently, the L-shaped mixing heads shown in Fig. 1 are well-suited for filling hollow profiles, such as window frames, refrigerator housings, and the like, with reaction plastics, particularly PUR foams. In order to clean the discharge unit 120, and in particular the discharge pipe, of reaction plastic remnants, or to prevent the adhesion and subsequent clogging of the discharge unit 120, a cleaning piston 130 is provided. The cleaning piston 130 is axially aligned with the discharge pipe; that is, the discharge pipe and the cleaning piston 130 share the same centerline x. The cleaning piston 130 has a circumference that corresponds to the inner circumference of the discharge pipe, allowing the cleaning piston 130 to move in a positive-adjustment manner within the discharge pipe. By this movement, the reaction plastic contained in the discharge pipe is expelled by pressure. A gap is provided between the discharge pipe and the cleaning piston 130 to allow movement of the cleaning piston 130 within the discharge unit 120. The size of this gap is within a certain range. Through frequent use of the mixing device 100, reaction plastic may adhere to the internal walls of the discharge unit 120 and harden. Consequently, the hardened reaction plastic will fill the gap, leading to increased friction between the discharge pipe and the cleaning piston 130. To eliminate or minimize this friction, lubrication of the discharge unit 120 and cleaning piston 130 is provided as described below. cwQcnn / zznz / E / Y In order to separate the cleaning piston 130 from a motor, for example, a hydraulic motor, a separating part or glass bell jar 160 can be provided, as shown in Fig. 1. This separating part 160 ensures that the reaction plastic carried by the cleaning piston 130 towards the motor remains within the separating part 160 and does not reach the motor. This prevents contamination and damage to the motor. For this purpose, the separating part 160 has a length equal to or greater than the stroke length of the cleaning piston 130. The structure of the cleaning piston 130 and the separating part 160, as well as the direction of the cleaning piston 130 for cleaning the discharge pipe, are well known to a skilled person, for example, from DE 10 2015 112 445 A1. Therefore, a detailed description of them will be omitted here. The mixing device 100 also comprises a fluid supply device comprising a gas supply device 140 and a lubrication device 150, which are connected to each other. The gas supply device 140 is used to provide a gas flow through the discharge unit 120, via an outlet 142 of the fluid supply device leading to the discharge unit 120. The gas to be conveyed through the discharge unit 120 can be supplied at an inlet 144 of the gas supply device 140 by means of a common conduit, for example, through a supply hose or pipe or the like. The gas supply device 140 is of particular interest if readily flammable reaction plastics or reaction plastics that produce readily flammable gases are processed using mixing devices 100. In this case, an inerting gas such as nitrogen, N₂, can be supplied through the gas supply device 140 in such a way that oxygen is removed from the discharge unit 120 and the components to be filled with the reaction plastic. For example, in the processing of pentane-activated foams, the discharge unit 120 and its atmosphere are filled with an inerting gas, such as nitrogen, through the gas supply device 140. In principle, the gas supply device 140 is structured as is known for mixing heads that use inerting gas. However, the gas supply device 140's piping is connected to the lubrication device 150 in order to moisten / lubricate the supplied gas with a lubricant provided by the lubrication device 150, if necessary. In particular, a duct, for example, a bypass duct, can be used to guide the gas from inlet 144 to a lubricant reservoir in the lubrication device 150. In the lubrication device 150, the gas is passed through or into a liquid lubricant reservoir and is moistened by lubricant droplets carried from the reservoir by the gas flow. This generates a mist of lubricant consisting of small lubricant droplets, which is carried by the gas flow through outlet 142 of the gas supply device 140. This moistened gas can be considered a fluid lubricant, supplied from the fluid supply device through outlet 142 to the discharge unit 120. For example, lubrication device 150 could be a grease gun, the operation of which is, in principle, understood by a skilled person. Alternatively, lubrication device 150 cwQcnn / zznz / E / Y could generate the nebulized lubricant itself, for example, by vaporizing the lubricant using a heating device. The gas flow is then directed solely through lubrication device 150 to transport the nebulized lubricant to the discharge unit 120. In Figures 1 to 4, the lubrication device 150 is shown located in the same housing as the gas supply device 140; that is, both devices are integrated into a single fluid supply unit. However, the lubrication device 150 could also be located upstream of the gas supply device 140, i.e., outside the housing shown in Figures 1 to 4. In this case, a branch in the gas line is located upstream of the inlet 144, and nebulized lubricant is conveyed along with the gas flow to the inlet 144 for distribution by the gas supply device 140 to the discharge pipe 120. This has the advantage that components of the lubrication device 150, such as a grease, can be supplied separately from the mixing device 100, thus preventing contamination of the lubricant.Furthermore, spatial separation facilitates the upgrade of the lubrication device 150 and is very cost-effective. The gas supply device 140 and the lubrication device 150 could also be provided as a fluid supply device within a head piece of the mixing device 100, i.e., as an integral part of the mixing device 100. In this case, the fluid supply device could be located, for example, at the beginning of the discharge unit 120 or discharge pipe in a region where the control piston crosses the discharge unit 120. But the fluid supply device could also be located opposite the mixing chamber 110 and the control piston 115, either as an integral part of the head piece of the mixing device 100 or—as shown in the figures—as an additional part that can be attached to the head piece. If necessary, the gas supply device connecting to the pipeline 140 and the lubrication device 150 can be equipped with a valve, for example, a pneumatic and / or hydraulic valve. This allows the gas flow through the lubrication device 150 to be interrupted, thus enabling the gas supply device 140 to operate without lubrication. In cases where the gas supply is provided solely for lubricating such a valve, this valve might be unnecessary, as the supply of the lubricating fluid can then be controlled by directly regulating the gas flow into or out of the gas supply device 140. In this case, ambient air could also be used as the lubricating gas. The lubricant may be any material that reduces friction between the discharge unit 120 and the cleaning piston 130 (or, if present, any remaining reaction plastic on them), and that does not lead to undesirable chemical reactions with the reaction plastic, such as enhanced foaming of the reaction plastic. Materials capable of softening or dislodging reaction plastic stuck in the discharge unit 120 and / or the cleaning piston 130 are preferred. In particular, plasticizers useful in plasticizing reaction plastic, such as C10-C21 sulfonic acid phenyl ester alkane (also known as Mesamoll), DEHP, DOP, or similar materials, are preferred. Release agents may also be used as a lubricant. Figures 2 to 4 show sections through the mixing device 100 of Figure 1 in different operating states of the fluid supply device, i.e., the gas supply device 140 and the lubrication device 150. The sections are taken parallel to the image plane of Figure 1 and, therefore, show the arrangement of the mixing chamber 110 including the control piston 115, the discharge pipe 120, the cleaning piston 130, and the gas supply device 140 / lubrication device 150. As can be seen in Figures 2 to 4, the outlet 142 of the fluid supply device is located in a region of the discharge pipe that forms a bypass with the mixing chamber 110. In other words, the outlet 142 is located in an area of ​​the discharge unit 120 that is only not blocked by the cleaning piston 130 if the cleaning piston 130 is withdrawn far enough from the discharge pipe to allow reaction plastic from the mixing chamber 110 to flow into the discharge pipe. Since the reaction plastic passes through the bypass, the bypass is also part of the discharge unit 120. This ensures lubrication occurs, in particular, in the region first contacted by the cleaning piston 130 during its cleaning stroke. This reduces friction at the start of the stroke, thereby decreasing the force applied to the cleaning piston 130 throughout the entire stroke. Furthermore, the lubricant distributed in an area near the head of the cleaning piston 130 is carried by the cleaning piston 130 through the discharge unit 120, ensuring lubrication along the entire stroke length of the cleaning piston 130. Additionally, since the gas carrying the lubricant is discharged from the discharge unit 120, the lubricant is carried along the entire length of the unit and wets its entire inner wall. This also ensures that the complete stroke of the cleaning piston 130 can be performed in a lubricated environment.Of course, outlet 142 can also be located in a different position within the discharge unit 120, if this is deemed necessary. Both the gas and the lubricant can be supplied through hoses or pipes to the fluid supply device, for example through inlet 144 or through other inlets (not shown). Within the housing containing the gas supply device 140 and lubrication device 150, a connection is formed between the two devices, for example, by means of a duct that carries gas to the lubricant reservoir, as described above. This duct may be able to be closed by a valve, for example, a pneumatic and / or hydraulic valve, in order to allow the supply of pure gas, without lubricant, as well as the supply of gas moistened / lubricated with the lubricant. As described above, gas lubrication can be carried out upstream of inlet 144 if the lubrication device 150 is positioned spatially separate from the mixing head or head piece of the mixing device 100. The duct branching off the main line of the gas supply device 140 and the corresponding valve are also then located upstream of inlet 144. The gas supply can be controlled via a valve containing a piston 146 to open and close the gas supply device 140. The valve could be either hydraulic or pneumatic. The valve could also be opened by gas pressure applied to it, although it is closed hydraulically. During the discharge of reaction plastic, the piston 146 closes to prevent the gas from mixing with the reaction plastic, which would lead to deterioration of the plastic's quality. This state is illustrated in Fig. 2, which shows the closed piston 146. By opening piston 146, as shown in Fig. 3, gas can be transmitted to the discharge unit 120. This could be done to clean the discharge unit 120 with pressurized gas, for example, ambient air, or to render the discharge unit 120 and the components to be filled with easily flammable reactive plastics inert. As finally shown in Fig. 4, even when piston 146 is open, the valve connecting the gas supply to the lubrication device 150 can be opened to allow gas to flow through the lubrication device 150 and carry the atomized lubricant 155 to the discharge pipe 120. In principle, this could be achieved by connecting a well-known grease containing the lubricant, via a valve-controlled duct or hose, to the gas inlet 144. For example, a bypass duct could be provided that diverts the gas lines from the gas supply device 140 and leads through the lubrication device 150. Gas currents over the lubricant contained in the grease carrier carry the lubricant with them, thus producing the misted lubricant 155. Due to the gas flow, the misted lubricant 155 is carried across the entire inner wall of the discharge unit 120, which is consequently moistened by the misted lubricant 155. In this process, the gas flow is adjusted so that the amount of lubricant carried with the gas is sufficient to moisten the inner wall of the discharge pipe 120, but does not form puddles that could lead to deterioration of the discharged reaction plastic. In this way, the lubricant is supplied precisely where it is most needed, namely on the inner wall of the discharge unit 120, but not on the glass bell side of the cleaning piston 130. For example, this can be done before discharging the reaction plastic to prevent it from adhering to the inner wall of the discharge unit 120. Furthermore, it should be emphasized that, in principle, since the humidified gas can also be supplied when the cleaning piston 130 is moving toward the discharge pipe, the entire external surface of the cleaning piston 130 can be lubricated. Moreover, installing a grease fitting as an additional lubrication device 150, connected to the gas supply 140, is simple in terms of construction but very costly and requires more delicate maintenance compared to lubrication systems used according to the prior art.Furthermore, allowing the gas flow to carry the nebulized lubricant enables a reliable lubricant dosage, as the quantity can be controlled primarily through the gas flow parameters. Alternatively, a gaseous lubricant could also be supplied from the fluid supply device, from the outside to outlet 142, to lubricate the discharge unit 120. As described above, the present invention provides an easily implementable, cost-effective, and reliable solution to the problem of supplying a lubricant to a discharge unit 120 of a mixing device 100 for the production of reaction plastic. This improves the service life of a cleaning piston 130 used to clean a discharge pipe of the discharge unit 120, thereby extending the overall service life of the mixing device 100. Furthermore, lubricating the discharge unit 120 improves the flow pattern of the reaction plastic during discharge, regardless of the presence of the cleaning piston 130. List of Reference Signals oyQcnn / zznz / E / YiAi 100 Mixing device 110 Mixing chamber 115 Control piston 120 Discharge unit 10 130 Cleaning piston 140 Gas supply device 142 Gas supply device outlet 144 Gas supply device inlet 146 Piston for opening and closing the gas supply device

Claims

1. A mixing device for generating reaction plastic, the mixing device comprising: a) a mixing chamber for mixing reactive components to generate the reaction plastic; b) a discharge unit connected to the mixing chamber for discharging the reaction plastic generated in the mixing chamber; and c) a cleaning piston axially aligned with a discharge pipe of the discharge unit and movable into the discharge pipe to clean the discharge pipe of reaction plastic;characterized in that the mixing device comprises: d) a fluid supply device for providing a lubricant in the discharge unit through an outlet, in order to lubricate the discharge unit, wherein i) the fluid supply device is configured to lubricate the movement of the cleaning piston in the discharge pipe, wherein i) the fluid supply device comprises a gas supply device for providing gas together with the lubricant, through the outlet to the discharge unit, wherein the fluid supply device is configured to provide the lubricant in the discharge unit while the cleaning piston moves into the discharge pipe, as well as while the cleaning piston moves out of the discharge pipe;e) a control piston, placed within the mixing chamber to control the flows of the reactive components, wherein i) an axial direction of the control piston is oblique, preferably perpendicular, to an axial direction of a discharge pipe of the discharge unit; f) wherein the fluid supply device comprises a lubrication device for providing the lubricant, the lubrication device being connected to the gas supply device; g) the lubrication device comprises a pneumatic and / or hydraulic valve; h) wherein the cleaning piston leaves open a bypass between the mixing chamber and the discharge pipe, if not used to clean the discharge pipe; ei) the outlet is located in the bypass between the mixing chamber and the discharge pipe.

2. The mixing device according to claim 1, further characterized in that the gas is an inerting gas, preferably nitrogen.

3. The mixing device according to claim 1 or 2, further characterized in that the fluid supply device is configured to provide the lubricant from the lubrication device as a nebulized lubricant contained in the gas from the gas supply device.

4. The mixing device according to any of the preceding claims, further characterized in that the lubrication device comprises a grease comprising the lubricant, through which the gas flow generates the nebulized lubricant.

5. The mixing device according to any of the preceding claims, further characterized in that it additionally comprises a separator part that separates the cleaning piston from a motor, preferably hydraulic, for actuating the cleaning piston, and whose length is equal to or greater than the stroke length of the cleaning piston.

6. The mixing device according to any of the preceding claims, further characterized in that the outlet is positioned opposite the control piston. QjQcnn / zznz / E / Y 7. The mixing device according to any of the preceding claims, further characterized in that the mixing device is for mixing at least two reactive components, preferably for mixing a polyol and an isocyanate in order to generate polyurethane foam, PUR.

8. The mixing device according to any of the preceding claims, further characterized in that the lubricant is a fluid plasticizer or release agent, in particular, a sultonic acid (C10-C21) phenyl ester-alkane.

9. The mixing device according to any of the preceding claims, further characterized in that the fluid supply device is located at the beginning of the discharge unit, preferably within a head piece of the mixing device and / or opposite the mixing chamber.

10. A method for generating reaction plastic using a mixing device according to any of the preceding claims, characterized in that: a) mixing reactive components in a mixing chamber to generate the reaction plastic; b) discharging the generated reaction plastic into the mixing chamber using a discharge unit connected to the mixing chamber; c) cleaning the discharge pipe of the reaction plastic with a cleaning piston that is axially aligned with a discharge pipe of the discharge unit and movable towards the discharge pipe;d) lubricating the discharge unit through a fluid supply device by proportioning a lubricant into the discharge unit through an outlet, wherein i) the fluid supply device is configured to lubricate the movement of the cleaning piston in the discharge pipe, wherein i) the fluid supply device comprises a gas supply device for providing gas together with the lubricant through the outlet, into the discharge unit; e) controlling the flows of the reactive components with a control piston placed within the mixing chamber; wherein i) a direction of the control piston is oblique, preferably perpendicular, to an axial direction of a discharge pipe of the discharge unit.

11. The method according to claim 10, further characterized in that, in the stage of providing the lubricant, the lubricant is provided by means of a lubrication device of the fluid supply device, the lubrication device being connected to the gas supply device, and wherein the lubricant can be provided by the lubrication device as a nebulized lubricant contained in the gas, and wherein the nebulized lubricant is contained in the gas from the gas supply device, and wherein the lubrication device includes a grease containing the lubricant, and wherein the gas can flow through the grease to create the nebulized lubricant.