JP2016159610A - Melt pump for extruding plastic melt through tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melt pump in which an inter-screw gap between two feed screws can be easily and arbitrarily adjusted.SOLUTION: The melt pump comprises: a compressor 406 having two feed screws 408, 408'; a transmission 405 by means of which the feed screws 408, 408' are synchronously drivable; and a drive 404, where the transmission 405 is disposed between the drive 404 and the compressor 406. Each of the feed screws 408, 408' has its own follower shaft 416, 416'. A coupling 414, 414' comprises: a driven ring gear 418, 418' provided on the follower shaft 416, 416'; a drive ring gear 419, 419' provided on the feed screw 408, 408'; and a clutch sleeve 421, 421' for gripping the driven ring gear 418, 418' and the drive ring gear 419, 419', where the drive ring gear 419, 419' and the driven ring gear 418, 418' have a different number of teeth.SELECTED DRAWING: Figure 13

Description

  The invention relates to a pressurized melt pump for extruding molten plastic from a tool according to the premise of claim 1.

  To manufacture plastic parts, first, molten plastics are produced in a screw apparatus by a polymerization process of various starting materials. Additives such as calcium carbonate, sawdust and glass beads may be added to the molten plastic. Needless to say, a melt produced from a regenerated raw material such as protein is also understood as a molten plastic. Such a screw device may be a mixer, an extruder, a screw kneader, or similar molten plastic production device.

  For example, Patent Document 1 discloses a screw device in which various starting materials are mixed and kneaded using a screw shaft that operates simultaneously until a fluid molten plastic is obtained.

  For the production of plastic pellets, the molten plastic is extruded from a tool, here a perforated disk, at a maximum of 30 bar and then processed, for example, on a plastic injection molding machine. In order to produce plastic profiles or plastic molded parts, it is necessary to extrude molten plastic from a suitable extrusion press tool or molded part tool at up to 300 bar in an extrusion press process.

  As is known from Patent Document 1, molten plastic is supplied from a screw device, for example, to a gear pump known from Patent Document 2, and is pushed through the tool from the gear pump or pressed against the tool to obtain desired pellets, irregular shapes. Materials or molded parts can be obtained.

  However, an independent gear pump has the disadvantage that it is expensive to manufacture, especially because it has its own drive and requires its own control. As another problem of the gear pump having its own drive device, vibration occurs due to the structure, especially when the rotational speed is as low as 50 rpm or less, and this vibration hinders the feeding of the molten plastic. Furthermore, when supplying molten plastic to the tool, not all of the molten plastic is pushed through the tool, but rather a portion of the molten plastic returns to the pump inlet opening where there is a corresponding and considerable inlet pressure. . However, since this inlet pressure is not uniform and occurs at a specific period like vibration, vibration occurs. In order to suppress this vibration-like inlet pressure, the melt must be supplied at a corresponding pressure, which requires sufficient pressure at the end of the screw device.

  Instead of the gear pump, a single screw pump having a unique driving device is often used. However, even in a single screw pump, due to the structure, a considerable inlet pressure is generated at the pump inlet, and it is necessary to suppress this pressure with a screw device and fill the screw groove.

  Therefore, the use of a gear pump or a single screw pump only has the advantage that the pressure boosting unit of the screw device can be reduced in size, and the generated inlet pressure must be suppressed by the screw device. It is impossible to omit it.

  Another disadvantage of gear pumps and single screw pumps is that after use, molten plastic remains between the gears or between the grooves of the screw, and it takes time to clean the gear pump or single screw pump.

  U.S. Pat. No. 6,057,059 teaches that a single drive drives a screw shaft together with a gear pump attached to the screw shaft by integrating the gear pump into the screw device. This has the advantage of operating the gear pump at the same high speed as the screw shaft, thereby minimizing vibration.

  From Patent Document 3, a twin-screw extruder incorporating a screw pump is known. In this extruder, two screw elements for increasing pressure are mounted on a screw shaft that operates simultaneously. Due to the specific screw shape, a space is formed between the screw elements, and this space makes it possible to pressurize the molten plastic by allowing a constant amount of molten plastic to be fed. However, in both the screw device according to Patent Document 1 and the twin screw extruder according to Patent Document 3, it is necessary to procure force and energy simultaneously from the drive device for pressure increase and for mixing and kneading processes. The entire equipment drive must be expanded. As a result, it is necessary to provide a very powerful electric motor and a correspondingly powerful transmission device, rotating shaft, casing and the like.

  In the screw device according to Patent Document 1 and the twin screw extruder according to Patent Document 3, the integrated gear pump and the screw element that provides pressure increase have the same rotational speed as the screw shaft used for mixing and kneading. A high number of revolutions is required to obtain a homogeneous molten plastic. As with screw elements that cause pressure increase, gear pumps generate this high rotational speed, but with high friction, resulting in increased power and energy consumption and heat generation. In doing so, heat can be transferred to the molten plastic which can be an obstacle or, in extreme cases, to cause damage to the molten plastic. As a result, the possibilities for application of integrated gear pumps and special screw elements are limited. This problem is alleviated by using individually adapted gear pumps or individually formed screw elements, depending on the molten plastic used. Similarly, this friction loss affects the entire drive and equipment, and the entire equipment needs to be reasonably large. However, this increases the equipment and installation costs and causes very severe wear.

  In this regard, the basis of the present invention is the high equipment costs associated with connecting the booster unit to the screw device, and in particular, neither the booster unit nor the screw device is any of these components without compromise. There is a recognition that can not be equipped.

  In that regard, Patent Document 4 describes an apparatus for producing plastic pellets, profile extrusion molded products or molded parts from molten plastic. In this device, the screw device is used only for mixing and kneading of the molten plastic, whereas the melting pump is designed only for pressure increase.

  A melt pump according to the premise of claim 1 has already been described in patent document 4, and the content of this specification is fully incorporated in this respect. In this type of melt pump with two supply screws designed exclusively for pressure increase, it is important to adapt the screw gap formed between the screw flights to the molten plastic to be processed each time. For example, in the case of polyethylene (PE), the screw gap is preferably 0.1 mm, while in the case of molten plastic with a high proportion of calcium carbonate, the screw gap is preferably 0.5 mm. For other additives such as sawdust and glass beads, a 1 mm or 2 mm screw gap may be appropriate.

European Patent Application Publication No. 0564 884 German Patent Application Publication No. 3842 988 EP 1 365 906 German Patent Application Publication No. 10 2013 010 505.6

  Based on this, the object of the present invention is to realize a melt pump of the kind described above in which the screw gap between the two supply screws can be easily and arbitrarily adjusted.

  As a technical solution to this problem, according to the invention, a melt pump of the kind described above having the features of claim 1 is proposed. Advantageous alternative forms of this melt pump can be taken from the dependent claims.

  Melt pumps formed in accordance with the present teachings have the advantage that the supply screw can be quickly and easily separated from the transmission by an easily removable coupling. Furthermore, this makes it possible to rotate the supply screws relative to each other about the longitudinal axis, and also to connect the transmission device at this new angular position. Thereby, the screw gap formed between the supply screws can be adapted to the molten plastic to be processed. At this time, it has been found that it is particularly advantageous to provide the driven ring gear of the driven shaft with a different pitch than the drive ring gear of the supply screw. Due to the difference in pitch in each ring gear, that is, the number of teeth, the position where the supply screw can be attached to the drive shaft becomes very large. As a result, the screw gap can be adjusted much more accurately.

  In a preferred embodiment, the drive ring gears of the first and second supply screws also have different numbers of teeth. Furthermore, when there are three types of ring gears, the number of possible positions further increases.

  The same applies when the number of teeth of the driven ring gear of the first and second driven shafts is different.

  In a particularly preferred embodiment, a particularly large number of positions are available for adjusting the angle of the supply screw due to the different number of teeth of all four ring gears in the two driven shafts and the two supply screws. Thereby, the screw gap can be adjusted particularly accurately. The calculation of an ideal tooth combination is very complex, so in practice use appropriate software.

  In yet another preferred embodiment, the coupling includes an adjustment disk that can be used to adjust the axial position of the supply screw. In this case, the actual axial position of the supply screw is calculated, and the thickness of the adjustment disk is selected so that the supply screw takes a desired position in the attached state.

  In another preferred form, the adjusting disk of the first joint is different in thickness from the adjusting disk of the second joint, so that the screw gap can be adjusted in the same way via the adjusting disk. Thereby, the screw gap can be adjusted more accurately.

  In a further advantageous embodiment, the two supply screws are arranged in an overlapping manner, i.e. perpendicular to each other. For this, the inlet opening is centered with respect to the supply screw

This has the advantage that the incoming melt is firmly captured by the two supply screws, thereby realizing a high filling rate. Furthermore, this has the advantage that the medium can be introduced and discharged radially by arranging the inlet opening on the side of the melt pump. On the other hand, this has the advantage that the melt pump can be arranged at an angle with respect to the screw device and the overall length of the device is reduced. For example, the melt pump can be installed at an angle of 45 degrees with respect to the screw device, which saves significant space.

In an advantageous embodiment, the supply screw is configured such that the ratio of the outer diameter (D _a ) to the core diameter (D _i ) is 2. In another embodiment, for example, when protein is introduced into molten plastic, the ratio of the outer diameter to the core diameter is 5. Depending on the type of molten plastic, the ratio of D _{a to} D _i can also be selected between 1.6 and 6. This achieves mass feeding when the screw is relatively thin and therefore inexpensive.

  An apparatus formed in accordance with the present teachings and a melt pump formed in accordance with the present teachings forcibly feeds melt in the melt pump, so that there is no significant inlet pressure at the inlet opening of the melt pump, resulting in There is an advantage that the melt can be transferred from the screw device to the melt pump without receiving pressure. Only the force necessary to overcome the force required to transport the molten plastic, for example, the inertia of the melt, friction, etc. (also referred to as the melt pressure) need to be applied by the screw device, depending on the nature of the melt. To a slight pressure increase of 0.4 bar. However, since such a force can be brought about by the screw itself of the screw device, the screw device may not have a pressure intensifier. On the other hand, a screw device without a pressure booster has a very small force to be transmitted, so a small drive device, in this case a small motor, in some cases a small transmission device, a small screw, a small screw, The advantage is that it can be operated with a casing and other smaller parts. This leads to a clear reduction in the manufacturing costs of the screw device. Along with this, energy costs are also reduced.

  Furthermore, by eliminating the pressure boosting device, the screw device can be designed for starting material mixing and for the production of molten plastic, which has the advantage of improving the efficiency of the screw device and thus the economics. At the same time, the burden on the screw device is reduced, thereby reducing wear.

  Furthermore, the separation of the melt pump from the screw device has the advantage that the melt pump can be constructed and designed only to achieve efficient pressure boosting.

  Surprisingly, it has been found that in the assembly and operation of the prototype of the device according to the invention, the total power to drive the screw device and the melt pump is less than the power of the corresponding device according to the prior art. Therefore, by separating the screw device and the melt pump, in addition to reducing the manufacturing cost of the device (due to the miniaturization of the component parts), the energy cost for manufacturing plastic pellets, profile extrusions and molded parts is also reduced. It was. In another advantageous embodiment, the screw flight has a rectangular or trapezoidal thread shape. Thereby, particularly when the flank angle (also referred to as profile angle) is selected between 0 degrees and 20 degrees, sufficient forced feeding of the melt is realized. The shape of the screw flight must be adapted to the melt used. For example, a profile angle of 0 degrees has been found suitable for processing polyethylene (PE), while PVC can be better processed with a profile angle of 13 degrees.

  In a preferred embodiment, the screw flight has a flat surface, which likewise contributes to cheap manufacturing.

  By forming a screw flight with a flat flank, a flank angle of 0 degrees, and a flat surface, the cross section of the screw flight is rectangular. Moreover, the screw clearance is uniform and minimized, especially when the spacing between screw flights approximately matches the width of the screw flights according to all gradients, and the corresponding screw space is sealed accordingly. This sealing allows high pressure on the tool, especially on the perforated disk.

  In yet another preferred embodiment, the screw flights of the two supply screws mesh with each other so that the screw gap remaining in the narrowest space forms a gap seal. This gap sealing, on the one hand, prevents back flow of the medium and enhances forced feeding, and on the other hand functions as a correction for overpressure. High pressurization is achieved by forced feeding, and at the same time, overpressure compensation prevents damage to the media, especially when the gap seal is compatible with the media being processed. The same advantages apply for the casing gap.

  As yet another advantage, the two supply screws can be driven with a relatively small output, which results in a smaller drive motor and lower energy consumption.

  In another preferred embodiment, a number of screw spaces are formed between the casing and the supply screw or its screw flight, and a medium is held in the screw space. The screw space is configured so as to be closed in accordance with the clearance of the screw gap and / or the casing gap, so that a desired pressure can be applied and forced feeding of molten plastic is realized. However, some pressure correction is performed even when there is excessive pressure (locally).

  In a preferred embodiment, the screw space extends along the slope of the screw flight. The beginning and end of the screw space lie in the connection between the two supply screws, i.e. the plane defined by the axes of the two supply screws. This has the advantage that the medium occupies a defined area and is not mixed with other media. At the same time, this allows an effective pressure on the perforated disk.

  In yet another preferred embodiment, a casing gap is formed between the screw flight and the casing, and a screw gap is formed between the screw flight and the adjacent supply screw. Since it is configured, the medium is basically held in the screw space, and does not flow back in large amounts to the adjacent screw space beyond the gap (gap sealing). For this purpose, the space between the screw spaces is thereby sealed, which allows high pressures in the individual screw spaces, forced feeding of molten plastic and pressures above 400 bar up to 600 bar for perforated discs. There is an advantage of doing.

  In yet another preferred embodiment, the casing gap and / or screw gap is between 0.05 mm and 2 mm wide. Ultimately, the width of the gap and the size of the resulting gap seal will depend on the medium being processed and its additives. For highly filled plastics with a proportion of calcium carbonate of 80% and a pressure on the perforated disk of 500 bar, a gap width of 0.5 mm has proved advantageous.

  As yet another advantage, quick pressurization on the one hand by the cooperation of two feed screws with correspondingly configured screw flights and meshing precisely with each other and on the other hand by forced feeding As a result, a high pressure can be realized with a melt pump having a relatively short structure, a residence time in the melt pump is short, and thermal and mechanical damage of the melt is small.

  In yet another advantageous embodiment, the melt pump is designed such that the feed screw rotates at a speed of 30 to 300 rpm, preferably 50 to 150 rpm, depending on the type of molten plastic. This makes the selected rotational speed at least in most cases higher than the rotational speed of the gear pump or single screw pump, so that the melt is almost in relation to the forced feed of the melt caused by the shape. Feeded without vibration.

  The advantage of limiting the rotational speed to a maximum of 300 rpm is to avoid detrimental polymer chain breakage that occurs when the rotational speed is high.

  In a preferred embodiment, when the feed pump length / diameter ratio is 2 to 5, preferably 3.5, the pressure on the perforated disc reaches more than 250 bar and a maximum of 600 bar. Thereby, there exists an advantage that a melting pump can be manufactured cheaply and can be installed in space saving.

  Further advantages of the melt pump according to the present invention will become apparent from the accompanying drawings and the embodiments described below. Likewise, the features described above and also further configured features can be used individually or in any combination in accordance with the present invention. The described embodiments are to be understood as having exemplary character and not final enumeration.

1 is a schematic plan view showing a first embodiment of a melting pump according to the invention of an apparatus for producing plastic pellets, profile extrusions or molded parts from molten plastic. It is side surface sectional drawing of the melting pump of FIG. Fig. 3b is a side cross-sectional view of a second embodiment of a melt pump according to the present invention taken along line III-III in Fig. 5a. FIG. 4 is a side cross-sectional view of the melt pump of FIG. 3 taken along line IV-IV of FIG. 5b. FIG. 5 is a cross-sectional view of the melt pump of FIG. 3 taken along line VV of FIG. FIG. 5 is a cross-sectional view of the melt pump of FIG. 3 taken along line VV of FIG. It is a side view of the supply screw of 3rd Embodiment of the melting pump by this invention. It is a side view of the supply screw of FIG. FIG. 7 is a side cross-sectional view of the supply screw of FIG. 6 taken along line VIII-VIII of FIG. It is an enlarged view of the circle VIIIa of FIG. It is a perspective view of the supply screw of 4th Embodiment of the melting pump by this invention. FIG. 10 is a side view of the supply screw of FIG. 9. FIG. 10 is a top view of the supply screw of FIG. 9. FIG. 10 is a front view of the supply screw of FIG. 9. It is side surface sectional drawing of 5th Embodiment of the melting pump by this invention. FIG. 14 is an exploded view of the joint of the melt pump of FIG. 13. It is an exploded view of the coupling of 6th Embodiment of the melting pump by this invention.

  FIG. 1 schematically shows an apparatus for producing plastic pellets, plastic profiles or plastic molded parts from molten plastic. This device comprises a screw device 1 for mixing and kneading molten plastic starting materials, a first embodiment of a melt pump 2 according to the invention for compressing molten plastic, and a tool 3, where The tool 3 is a perforated disc from which molten plastic compressed to more than 50 bar is extruded therefrom to produce the desired plastic pellets. In an embodiment not shown here, instead of a perforated disk, an extrusion press tool for producing the desired plastic profile or the desired plastic molded part can be used and the tool can be subjected to pressures of more than 250 bar. .

  In the embodiment illustrated herein, the melt pump is positioned at an angle of 45 degrees with respect to the screw device, reducing the space required at the manufacturing facility.

  In particular, it can be seen from FIG. 2 that the melt pump 2 comprises a drive, here an electric motor 4, a transmission device 5 and a compressor 6. Two supply screws 8 are arranged and supported in parallel with each other in the casing 7 of the compressor 6 and rotate in opposite directions. The supply screw 8 is connected to the transmission device 5, and the transmission device 5 is connected to the electric motor 4. Each of these two supply screws 8 has a spirally extending screw flight 9 protruding basically radially, and the screw flight 9 of one of the supply screws 8 is forcibly feeding molten plastic. , Meshing with the screw flight 9 of the other supply screw 8.

  In the first embodiment of the melt pump 2 according to the invention shown in FIG. 2, the two supply screws 8 rotate in opposite directions. The supply screw 8 is forcibly connected via the transmission 5 in order to guarantee a precise and accurate engagement with each other, so that the simultaneous operation of the supply screw 8 is guaranteed. At this time, the two supply screws 8 are driven in synchronization.

  The casing 7 is formed to correspond to the supply screw 8 so that a narrow casing gap 10 remains between the outer edge of the screw flight 9 and the casing 7, and this gap may be 0.05 mm to 2 mm, In the embodiment illustrated herein, it is 0.5 mm.

  When the screw flight 9 projects radially and the flank is flat, and particularly when the flight surface is flat, the flank angle of each face of the screw flight 9 is 0 degrees. The cross section of the screw flight 9 is rectangular. At the same time, the spacing between adjacent screw flights 9 corresponds to the width of the screw flights 9. From this, it can be seen that the screw flight 9 of one supply screw 8 meshes exactly with the gap of the screw flight 9 of the other supply screw 8. At this time, the screw gap 11 remaining between the screw flight 9 and the supply screw 8 is minimized, and is 0.05 mm to 2 mm, preferably 0.5 mm. The actually selected screw gap 11 varies depending on the medium used, and a correspondingly wide screw gap 11 is selected as the viscosity of the medium increases. By minimizing the screw gap 11, the space between the adjacent supply screws 8 is sealed, and as a result, a large number of screw spaces 12 are formed between the casing 7, the screw flights 9, and the supply screws 8. Due to the sealing, the screw spaces 12 are each closed, and the molten plastic present therein is continuously forced. The supply screws 8 that closely mesh with each other minimize the backflow of a portion of the molten plastic and, as a result, the pressure loss is minimized. This is also called dense in the axial direction.

In order to obtain a high feeding capacity, the screw space 12 is configured to be relatively large. This is realized by increasing the screw flight 9, and the ratio of the outer diameter (D _a ) to the core diameter (D _i ) is 2.

  In order to reduce the size of the melt pump 2, the supply screw 8 has a length / outer diameter ratio of 3.5 in the embodiment illustrated herein.

  The screw space 12 formed inside the casing 7 is partitioned toward the outside of the casing 7 and to the side of the screw flight 9. In the region where the screw flights 9 of the adjacent supply screws 8 mesh with each other, the screw spaces 12 are separated from each other by a sealing action. As a result, one screw space 12 extends into one screw groove.

  The form of the width of the casing gap 10 and / or the screw gap 11 varies depending on the material used. For example, when processing highly filled plastics with a calcium carbonate percentage of 80%, it has been found that a width of 0.5 mm is appropriate if the required pressure is 250 bar. In the medium having high fluidity, the gap is made smaller, and in the medium having low fluidity, the gap is made larger. In the case where hard particles, fibers or pigments are mixed in the medium, the gap can be made larger as well.

  The casing gap 10 and the screw gap 11 allow the formation of a substantially closed screw space 12, which in particular presses the perforated disc 3 because it prevents a significant back flow of the medium.

  If the pressure rises locally beyond the desired degree, the gap acts in a corrective manner, i.e. some molten plastic can leak into the adjacent screw space 12, thereby causing a local pressure. Drops again and clogging and / or breakage is avoided. Therefore, the size of the gap also affects the pressure correction. When high pressure is required in the tool 3, it is necessary to make the casing gap 10 and the screw gap 11 small. This is also true when processing highly viscous molten plastic. In the case of low viscosity molten plastic, the gap can also be expanded.

  Ultimately, the gap can be selected for individual examples according to the criteria described herein. It has been found that a suitable gap width is 0.05 mm to 2 mm. All embodiments described herein are considered axially dense.

  The embodiment described here of the melt pump 2 with a gap width of 0.5 mm is particularly advantageously a highly filled plastic, i.e. a plastic with a high proportion of solids such as, for example, calcium carbonate, wood, carbide. Applicable to. At this time, the highly filled plastic has at least 80% calcium carbonate.

  Because there are many molten plastics, the flank angle (also called profile angle) can be adapted to any required shape. At this time, it has been found that it is advantageous to select the rectangular thread shape shown in FIG. 2 or the trapezoidal thread shape shown in FIG.

  The rectangular thread shape as shown in FIG. 2 is also used for processing polyethylene (PE).

  In the second embodiment of the melt pump 102 according to the invention shown in FIGS. 3 to 5, the two supply screws 108 rotate in opposite directions and are driven by a common drive shaft 113. Again, the screw flights of the supply screw 108 mesh with each other to leave a minimum screw clearance.

This type of highly filled plastic can be transported and compressed using the melt pump 2, 102 without damaging the material, and the plastic enters the melt pump 102 at ambient pressure and at a pressure of 50 to 600 bar, preferably 400 bar. It is discharged from the melt pump 102. Again, the ratio of D _{a to} D _i is 2 in order to achieve a high feeding capability.

FIGS. 6 to 8 show a supply screw 208 of a third embodiment of a melt pump according to the present invention. The supply screw 208 is configured in two strips, and the screw flight 209 is configured in a trapezoidal shape having a cross section of 13 degrees in flank angle. The supply screw 208 is disposed in the reverse direction, and is preferably used for processing PVC. Also in this case, a dense screw space 212 is formed in the axial direction, thereby realizing sufficient pressurization and sufficient forced feeding. In this case, the ratio of D _{a to} D _i is 2 as well.

9 to 12 show a supply screw 308 of a fourth embodiment of a melt pump according to the present invention. The supply screw 308 is configured in four strips (A, B, C, and D), and the screw flight 309 is configured in a rectangle having a cross section and a flank angle of 0 degrees. This supply screw 308 is arranged in the opposite direction and is preferably used for processing of protein-containing media. Also in this case, a dense screw space 312 is formed in the axial direction, thereby realizing sufficient pressurization and sufficient forced feeding. In this case, the ratio of D _{a to} D _i is 2 as well.

  In the fifth embodiment of the melt pump 402 according to the invention shown in FIGS. 13 to 14, the compressor 406, the transmission device 405 and the drive device 404 are formed in the same way as in the first embodiment of FIG. The difference is that in the fifth embodiment, two supply screws 408 and 408 ′ are detachably connected to driven shafts 416 and 416 ′ of the transmission device 405 via joints 414 and 414 ′, respectively. Each of the two driven shafts 416 and 416 ′ is formed with helical teeth 417 and 417 ′, and these helical teeth are further connected to the two driven shafts 416 and 416 ′. Accordingly, the supply screws 408 and 408 ′ are meshed with each other so as to be synchronized. This achieves accurate simultaneous operation of the supply screws 408, 408 ', so that the positions of the screw flights 409, 409' do not change relative to each other during operation.

  The joints 414 and 414 ′ are respectively driven ring gears 418 and 418 ′ provided at the free ends of the driven shafts 416 and 416 ′ and drive ring gears 419 provided at the corresponding free ends of the supply screws 408 and 408 ′. 419 ′, adjustment disks 420, 420 ′, and coupling sleeves 421, 421 ′. The coupling sleeves 421 and 421 ′ include inner driven teeth 422 and 422 ′ and driving teeth 423 and 423 ′, and the driven teeth 422 and 422 ′ correspond to the driven ring gears 418 and 418 ′ of the driven shafts 416 and 416 ′. On the other hand, the drive teeth 423 and 423 ′ are formed to correspond to the drive ring gears 419 and 419 ′ of the supply screws 408 and 408 ′. In the embodiment illustrated herein, spur teeth were selected according to DIN 54480.

  In the mounted state, the coupling sleeves 421, 421 ′ cover both the driven ring gears 418, 418 ′ and the drive ring gears 419, 419 ′, so that the driven teeth 422, 422 ′ are driven ring gears 418, 418 ′, Further, the drive teeth 423 and 423 ′ mesh with the drive ring gears 419 and 419 ′. As a result, the joint sleeves 421 and 421 'can transmit forces and moments from the driven shafts 416 and 416' to the supply screws 408 and 408 '.

  In order for the screw flights 409, 409 'of the meshing supply screws 408, 408' to always engage each other, the supply screws 408, 408 'need to be adjusted relative to each other. This is done by rotating one or two of the supply screws 408, 408 'about their respective longitudinal axes until the desired position is reached. At this time, the size of the screw gap 411 is also adjusted to a desired level.

  The driven ring gears 418, 418 'of the driven shafts 416, 416' have a large number of teeth, and the number of teeth is different from the number of teeth of the drive ring gears 419, 419 'of the supply screws 408, 408'.

  Therefore, the supply screws 408, 408 'can be shifted according to the pitch of the drive ring gears 419, 419' or according to the pitch of the driven ring gears 418, 418 '. Of course, the supply screws 408, 408 'can be displaced in either the drive ring gear 419, 419' or the driven ring gear 418, 418 '. Furthermore, the first supply screw 408 can be offset differently from the second supply screw 408 '.

  As a result, this reveals that there are many possibilities for positioning the supply screws 408, 408 'with respect to each other. In practice, in order to optimally position the supply screws 408, 408 'relative to each other, the tooth combination is calculated and verified using appropriate software. In accordance with the calculated tooth combination, the joint sleeves 421 and 421 ′ are fitted into the driven shafts 416 and 416 ′, and the supply screws 408 and 408 ′ are fitted into the joint sleeves 421 and 421 ′ at the calculated positions accordingly. Plug in.

  The position of each supply screw 408, 408 'is adjusted in the axial direction using the adjustment discs 420, 420'. At this time, first, the actual positions of the screw flights 409 and 409 'are mutually calculated. Accordingly, a first adjustment disk 420 having a first thickness and a second adjustment disk 420 ′ having a second thickness are selected to produce a desired screw gap 411, and the first The adjustment disk 420 is disposed between the first supply screw 408 and the first driven shaft 416, while the second adjustment disk 420 ′ is disposed between the second supply screw 408 ′ and the second driven shaft 416 ′. Place between.

  In the fifth embodiment shown in FIGS. 13 and 14, the pitch of the driven ring gears 418 and 418 'of the first and second driven shafts 416 and 416', that is, the number of teeth is the same. The same applies to the drive ring gears 419, 419 'of the first and second supply screws 408, 408'.

  The sixth embodiment of the melt pump according to the present invention shown in FIG. 15 is different from the fifth embodiment shown in FIGS. 13 and 14 in that the number of teeth of the driven ring gear 518 of the first driven shaft 516 is The only difference is the number of teeth of the driven ring gear 518 ′ of the second driven shaft 516 ′. That is, the driven ring gear 518 provided with spur teeth of the first driven shaft 516 has a total of 16 teeth, and the driven ring gear 518 ′ of the second driven shaft 516 ′ has a total of 17 teeth. On the other hand, the drive ring gear 519 of the first supply screw 508 has 18 teeth, respectively, like the drive ring gear 519 ′ of the second supply screw 508 ′. This clearly increases the possible tooth combinations because the two joints 514, 514 'are provided with three different ring gears, so that the screw gap 511 can be adjusted more precisely.

  In another embodiment not shown here, the four ring gears provided in the two joints all have a different number of teeth, so that more tooth combinations are available.

Claims (15)

The compressor (406) having two supply screws (408, 408 ′) arranged in the casing and the supply screws (408, 408 ′; 508, 508 ′) can be driven synchronously via the compressor (406). A pressure melting pump for extruding molten plastic from a tool, including a transmission device (405) and a drive device (404), wherein the transmission device (405) includes the drive device (404) and the compressor ( 406) and a unique driven shaft (416, 416 ′; 516, 516) for each of the supply screws (408, 408 ′; 508, 508 ′) in the transmission (405). '), And the supply screw (408, 408'; 508, 508 ') is connected via a joint (414, 414'; 514, 514 '). In melt pump, which is connected to the driven shaft to respond (416,416 '),
The joint (414, 414 ′; 514, 514 ′) is a driven ring gear (418, 418 ′; 518, 518 ′) provided on the driven shaft (416, 416 ′; 516, 516 ′); A drive ring gear (419, 419 ′; 519, 519 ′) provided on a supply screw (408, 408 ′; 508, 508 ′), the driven ring gear (418, 418 ′; 518, 518 ′) and the Including a coupling sleeve (421, 421 ′) for gripping the drive ring gear (419, 419 ′; 519, 519 ′), and the drive ring gear (419, 419 ′; 519, 519 ′) and the driven ring A melt pump characterized in that the gears (418, 418 '; 518, 518') have a different number of teeth.   The melt pump according to claim 1, wherein the drive ring gear of the first supply screw has a different number of teeth from the drive ring gear of the second supply screw.   The driven ring gear (518) of the first driven shaft (516) has a different number of teeth than the driven ring gear (518 ') of the second driven shaft (516'). Item 3. The melting pump according to Item 1 or 2.   The joint (414, 414 ′; 514, 514 ′) includes a replaceable adjustment disk (420, 420 ′), which is replaced by the drive shaft (418, 418 ′). 518, 518 ') and the supply screw (408, 408'; 508, 508 '), melting according to any one of claims 1 to 3, characterized in that pump.   The adjustment disk (420) of the first coupling (414; 514) has a different thickness than the adjustment disk (420 ') of the second coupling (414'; 514 '). Item 5. The melt pump according to Item 4.   The first driven shaft (416; 516) is operatively connected to the second driven shaft (416 ′; 516 ′) via helical teeth (417, 417 ′; 517, 517 ′). The melt pump according to any one of claims 1 to 5, characterized in that the supply screw (408, 408 '; 508, 508') is driven synchronously.   7. Two feed screws (8, 208, 408, 408 ′, 508, 508 ′) according to any one of claims 1 to 6, characterized in that they are arranged one above the other, ie vertically. The melt pump described. The supply screw (8, 108, 208, 308, 408, 408 ′, 508, 508 ′) has a ratio of the outer diameter (D _a ) to the core diameter (D _i ) of 1.6 to 6, preferably 2. It is formed so that it may be 0 to 5.0, The melt pump as described in any one of Claim 1 to 7 characterized by the above-mentioned.   The screw flight (9, 209, 309, 409, 409 ′) provided on the supply screw (8, 108, 208, 308, 408, 408 ′, 508, 508 ′) performs forced feeding of the medium. The melt pump according to claim 1, wherein the melt pump is formed as follows.   The screw flight (9, 209, 309, 409, 409 ′) has a rectangular or trapezoidal thread shape, and the profile angle (α of the screw flight (9, 209, 309, 409, 409 ′)) ) Is 0 to 20 degrees, the melt pump according to claim 9.   The screw flight (9, 209, 309, 409, 409 ′) and the supply screw (8, 108, 208, 308, 408, 408 ′, 508, 508 ′) are unique to the casing (4). At least one screw space (12,) between the supply screw (8, 108, 208, 308, 408, 408 ', 508, 508') having a screw flight (9, 209, 309, 409, 409 '). 212, 312) are formed and the screw spaces (12, 212, 312) correspond to each other such that the rest of the casing gap (10) and / or the screw gap (11, 411, 511) is closed. 11. The method according to claim 9 or 10, characterized in that they are formed and arranged so as to mesh with each other. Melt pump.   The casing (7) corresponds to the outer shape of the supply screw (8, 108, 208, 308, 408, 408 ′, 508, 508 ′), and the supply screw (8, 108, 208, 308, 408, 408 ′, 508, 508 ′) and the casing gap (10) remaining between the casing (7) are formed such that the casing gap (10) is small enough to provide gap sealing, and The screw flight (9, 209, 409, 409 ′) and the supply screw (8, 108, 208, 308, 408, 408 ′, 508, 508 ′) are connected to the screw flight (9, 209, 309, 409). 409 ') and the supply screw (8, 108, 208, 308, 408, 408', 508, 508 ') The remaining screw gaps (11, 411, 511) are formed so as to correspond to each other so that the screw gaps (11, 411, 511) become small enough to provide gap sealing, and are arranged so as to mesh with each other. The melt pump according to any one of claims 9 to 11, wherein the melt pump is provided.   Depending on the medium, the casing gap (10) and / or the screw gap (11, 411, 511) are chosen such that the compressor (6, 406) is considered axially dense. The melt pump according to claim 12, characterized in that:   In the drive device (4, 404) and the transmission device (5, 405), the rotation speed of the supply screw (8, 108, 208, 308, 408, 408 ′, 508, 508 ′) in the previous period is 30 to 300 rpm, preferably The melt pump according to any one of claims 1 to 13, characterized in that is designed to be between 50 rpm and 150 rpm.   The feed screw (8, 108, 208, 308, 408, 408 ', 508, 508') has a length / outer diameter ratio of 2 to 5, preferably 3.5. The melt pump according to any one of 1 to 14.