JPH01285308A - Press for manufacturing plastic blank - Google Patents

Abstract

PURPOSE: To continuously extrude a blank without generating a spiral eye or an inner twist by concentrically bearing a rotor in a rotor housing, forcibly controlling a peeling knife provided at an upper end of an outlet sector part, and raising it so as not to be barely brought into contact with the rotor. CONSTITUTION: A circular rotor 3 is concentrically borne, and a rotor housing 2 is preferably in a cylindrical shape. A material is conveyed from a vacuum chamber 6 toward a die 5. And, the material compressed in a material conveying segment 7 is released from the rotor 3 by a peeling knife 13 provided at an upper end of an outlet sector part 15 at each time. To prevent a disadvantageous metal galling, the knife 13 must be considered so as not to be barely brought into contact with a surface of the rotor. A gap is 0.05 to 2 mm or particularly desirably 0.3 to 0.5 mm. this is performed by forcibly controlling the knife 13. The knife follows a surface contour of the rotor at a predetermined distance by the forcible control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a press for producing plastic blanks, in particular ceramic cylindrical blanks for insulators.

[Conventional technology]

Presses of this type are known. The screw press is
It is a device that is often encountered for deforming plastic materials, such as is used in brick-making factories, for example in the ceramic industry or the building materials industry.
l, Volume 116, No. 11983, Pachber
(See page 25 et seq.). This press, called an extruder, has long been criticized. because,
This is because all types of screw presses have a number of disadvantages that are unacceptable depending on their intended use.

Swiss Patent No. 334,552 points out deficiencies and drawbacks of screw presses. For example, it has been pointed out that there is a disadvantage in efficiency and in the formation of an S-shaped structure in the extruded strands of material. The formation of this structure results in poor yields in the ceramic industry. However, the extruder described herein does not eliminate all drawbacks. This is particularly because the material fed from the feed roll is forced into the subsequent die without being controlled by the work roll. The rotor used is not circular and there are no material strippers.

A screwless extruder is known from German Patent No. 2 227 525. This extruder is equipped with a roll-shaped rotating body, a so-called rotor. This roll-shaped rotating body is provided with an annular groove perpendicular to the central axis over its entire length. In this annular groove, the plastic material is conveyed in the circumferential direction of the rotating body. The roll-shaped rotating body rotates with small play inside a horizontally placed cylindrical housing. In this case, a supply roll fills the annular groove with material. A tangential stripper is provided in each groove. This stripper removes plastic material from the groove at the exit of the roll. When producing cylindrical blanks for insulators, the deflection of the emerging strands has a disadvantageous effect in order to obtain concentric eyes. Due to the large number of annular grooves, a large surface still moves relative to the conveyed material. This results in disadvantageous wear and tear.

In practice, it has not been possible to replace screw presses, although in the case of rotary presses screws are no longer used as a material transport mechanism.

A screwless pump for slurry, slaked lime, etc. is known from DE 1019964 A1. This pump has an eccentric circular rotor and a controlled material transport web. The die is provided tangentially to the rotor. This does not indicate in any way that the pump can be used for the production of plastic blanks.

DE 50 009 points out that in the case of screw presses, considerable power is required to overcome the friction of the material in the screw. The drum described in this document for sliding compressed material in a brick press is equipped with a force-controlled conveying web. However, with this device it is not possible to produce plastic blanks with concentric eyes.

A press of the type mentioned at the outset for producing ceramic blanks is known from German Patent No. 486,214. This press has a device for feeding ceramic starting material and a circular rotor arranged concentrically in a rotor housing. This circular rotor serves to transport the material and carries at least one force-controlled material transport web.

DE 12 29 279 A1 describes an extruder for processing plastic or plasticizable materials, in particular synthetic resins.

This extruder is a special embodiment (West German Patent Application Publication No. 1)
229279) has an eccentrically mounted rotor. A number of cams are provided on this rotor. Furthermore, the inner wall of the rotor housing is provided with a cam.

A material stripper that scrapes the surface of the rotor serves to skim material and deflect the material toward the die.

This press cannot be used with ceramic materials. This is because ceramic materials generally cannot be transported by this means. This press does not have a pull-in roll and a vacuum chamber to evacuate the material strand. The cam on the inner wall of the housing cannot be used with ceramic materials. This is because the material does not flow through the valley.

The stripping tool elastically presses against the surface of the rotor. This is completely unusable with ceramics. because,
This is because the ceramic material must be completely free from metal parts. This is not achievable due to the abrasion caused by the stripper.

DE 33 27 115 A1 describes an eccentrically mounted rotor. In this case, the rotor is equipped with a force-controlled transport web. This conveying web carries out the material conveyance and the precompression of the ceramic material, but the production of a rotor with a conveying web that is forcedly controlled inside the rotor is very structurally complex.

Furthermore, the narrow space in the rotor allows stable drive, support, control and guide elements to be designed correspondingly to the required mechanization only in the case of large machines. Due to the limited space, it is very time consuming to assemble the necessary mechanical parts. This also applies to repairs. Perfect sealing of the conveying web is structurally expensive and requires repairs.

[Problem of invention]

It is therefore an object of the present invention to avoid the use of compression screws, to provide a centrally mounted rotor which contains no moving parts and which advances the material flatly in the plane of the central axis of the blank to form a wig. It is an object of the present invention to provide a press of the type mentioned at the outset, which allows blanks to be extruded continuously without crevices or internal twisting.

[Means to solve the problem]

This problem includes a material supply port and a rotor, the rotor is installed in a rotor housing and serves to generate pressure and transport the material, and the rotor is provided with at least two dendritic cams, which cams are connected to the rotor axis. In a press for producing plastic blanks, in particular ceramic cylindrical blanks for insulators, which extend in the direction and are provided on the outer circumferential surface of the rotor, the rotor is concentrically supported in the rotor housing and the upper end of the outlet sector The problem is solved by the fact that the section is provided with a stripping knife which is forcefully controlled and rises and lowers during movement of the rotor in such a way that it barely touches the rotor.

〔Effect of the invention〕

New presses have very little scrap. The press has a centrally mounted rotor which transports and compresses the material. In this case, no unacceptable eyes will be formed.
This is particularly important for highly demanding ceramic cylindrical blanks.

The new press does not have the other disadvantages of screw presses, in particular the friction of screw presses and the large amount of energy required, in areas of use where S-shaped twisting of the cylindrical blanks due to screw transport is not important. The friction of the circular rotor in contact with the plastic material is small compared to that of a screw press. The press can be equipped with a vacuum chamber according to the prior art without any problems. Therefore, the problem of evacuation of special quality cylindrical blanks does not arise.

〔Example〕

The present invention will be explained in detail based on the figures.

As shown in FIGS. 1, 3 and 4, the dosing of the material takes place via a dosing screw 10, as in the prior art. Material can be introduced into this metering screw via a material feed opening 9 . The metering screw 10 is driven by an electric motor 18 .

In front of the dosing screw 10, a grooved plate 11 is provided, as in the prior art.

In this grooved plate, the plastic material is subdivided into strips. The first task of the grooved plate 11 is to seal the subsequent vacuum chamber 6 to the material charging side. Vacuum chamber 6
Inside, the strip that falls into it is evacuated. In the case of plastic materials that can be unacceptably dehydrated in the vacuum chamber, a spray device 16 can be used.

The material strip reaches the dosing roll 1 in the vacuum chamber 6 .

This dosing roll supplies the circular rotor 3 with material. The dosing roll 1 (which may be omitted) serves in particular to prevent undesired material build-up in the vacuum chamber 6. In the case of another embodiment of the invention in which the metering roll 1 is not provided, the operating range of the cam 4 (described later) of the circular rotor 3 extends to the die 5 of the press and the wall on the opposite side of the circular rotor 3. reached,
It extends to the entire vacuum chamber 6.

A circular rotor 3 is mounted concentrically within the rotor housing 2. The rotor housing 2 is preferably cylindrical. However, different shapes of the rotor housing can be selected for the known circular piston rotors.

In this case, a circular rotor with a cam is designed to match the shape of the rotor housing.

A tree-like cam 4 is formed on the entire outer peripheral surface of the rotor 3 and extends in the direction of the rotor axis. At least two, preferably four, of these cams are provided on the outer peripheral surface of the rotor.

However, the number of cams is not limited, and there are 4 cams.
It is possible to provide more than one. The cams are ideally spaced equidistantly on the rotor surface. The intermediate chamber between the highest points of two adjacent cams forms a material transport segment 7.

The maximum height of the cam, measured from the rotor surface, is designed such that a gap of preferably 0.5 to 1M is formed between the maximum height of the cam and the inner wall 12 of the rotor housing.

Depending on the material to be compressed, the rotor housing inner wall 12-
It is recommended that the cams transport along this inner wall without contact - be coated with a wear-resistant material.

On the one hand, the dendritic cam transports the material from the vacuum chamber 6 towards the die 5 . On the other hand, the material is precompressed in the material conveying segment 7.

The shape of the dendritic cam is not constrained. Some possible shapes are shown in Figures 5a to 5d. For example, the draft angle in the rotor rotation direction (the angle between the rotor surface and the rising or inclined side surface of the cam) may be smaller than the draft angle in the opposite direction to the rotor rotation direction, see Figures 5a and 5d. ), may be larger (see Figure 5b)
, and both draft angles may be the same size (see Figure 5C).
. The shape of the patterned side may be straight or curved (toward or away from the rotor center).

The maximum height of the cam above the rotor surface may be formed as a lip. However, the transition from the rising side to the inclined side must be continuous.

Upon rotation of the rotor, the cam opens the outlet cross section 8 at the lower end of the die adapter. This exit cross-section is always at its maximum when the height of the cam passing over the rotor surface is at its minimum.

An outlet sector 15 is open in front of the outlet cross section 8 . This outlet sector extends to the stripping knife 13 and is a predetermined section of the outer circumference of the rotor housing 2. The size of the outlet sector 15 is determined by the diameter ratio of the circular rotor to the rotor housing. Within the exit sector, cam 4
The material fed from the material conveying segment is layered flat to the desired layer thickness.

Stripping knife 1 provided at the upper end of the outlet sector 15
3, the material compressed in each material conveying segment 7 is peeled off from the circular rotor 3. In order to prevent disadvantageous metal wear, care must be taken that the stripping knife 13 barely touches the rotor surface; a clearance of 0.05 to 2 m, especially preferably 0.63 to 0.5 m, is preferred. has been proven. This is achieved by forcefully controlling the stripping knife 130.

This forced control causes the knife to follow the surface contour of the rotor at a fixed distance. The force control device can be provided both inside the press and outside the press.

In FIGS. 1, 3 and 4, three embodiments of a forced control device are shown.

In FIG. 1, the knife is held by at least two guide rods 28. In FIG. This guide bar on the one hand prevents the stripping knife from twisting or tilting in or against the direction of rotor rotation, and on the other hand ensures that the knife moves up and down in accordance with the surface contour of the rotor. The actual vertical movement of the stripping knife is effected by in each case at least one guide roller 17, which is arranged on the guide rod. This guide roller engages in the guide groove 14 of the control disk 30. The guide groove 14 extends over the control disk 30 such that its defining edge represents a projection of the rotor cross-section including the cam.
It is milled. That is, the control disk may be larger or smaller in diameter than the rotor. The control disc is driven via shaft 25. This shaft rotates synchronously with the rotor, ie with the same angular velocity. A separate, own control disk may be provided for each guide rod with at least one guide roller. However, if the guide grooves 14 are milled on both sides of the control disk, one control disk may also control two guide rollers fixed to the guide rod. The distance of the stripping knife 13 from the rotor surface can be adjusted by sliding the shaft 25 and thus the control disk 30 parallel to the lifting direction of the stripping knife.

A second embodiment of forced control of the stripping knife consists in providing at least two contact rollers 26 along the edge of the stripping knife facing towards the rotor surface. This contact roller contacts the contour of the rotor surface. Preferably,
Attached to the outer ends of the stripping knives are in each case one contact roller which is displaced over the outer edge of the rotor.

Furthermore, care must be taken that the stripping knife is pressed with sufficient pressure towards the rotor surface. This can be accomplished, for example, in two different ways (Figures 3 and 4).
(see figure).

In the case of FIG. 4, the stripping knife, which is fixed to at least two guide rods 28 as shown in FIG. 1, is pressed in the direction of the rotor by a coil spring provided around the guide rods. The coil spring 29 is supported on one side by the outer housing wall. This housing wall is also
It has a function of guiding the guide rod 28. The knife thus does not twist or tilt together with the guide rod; the other side of the coil spring 29 is supported by a disc-shaped collar fixedly connected to the guide rod.

In the case of FIG. 3, a stripping knife is rotatably fixed in the press to the upper housing wall. The stripping knife is preferably journalled at at least two pivot points 27.

The pivot point can be designed as a hinge, for example.

In this embodiment, the necessary pressing force in the direction of the rotor is exerted by the extruded material itself. In order to ensure free rotation of the stripping knife during operation, a material deflection plate 19 is installed on the inner wall of the housing immediately in front of the stripping knife.
It is useful to provide . This prevents material from penetrating the variable intermediate space between the upper edge of the knife and the housing wall. If penetrated, free rotation of the stripping knife would be prevented.

A die 5 is provided in front of the outlet sector 15.

In this die, a cylindrical blank (semi-finished product) is formed from plastic material. In this case, the pre-compacted material rests in a flat layer on the material in the die. The material feed rate per material transport segment 7 determines the layer thickness.

The use of dice itself is known. A preferred die is shown in Figures 2a and 2b.

This die, in cooperation with the circular rotor 3, can take into account the particularities of the cylindrical blank produced by the circular rotor. When manufacturing insulators for use in the ceramic industry, cylindrical blanks are desired. However, it is obvious that blanks of any other shape can be produced depending on the intended use. In a preferred embodiment, the die 5 has as its main component a section 20 with a square inlet and a rounded outlet.

This outlet is connected directly to the outlet section 15.

The transition from a square (usually square) part to a round part is
This is done in that the square part is designed as a funnel with a side inclination angle of at least 30°. Moreover, the square section is very short, significantly shorter than the rounded section 21 that follows it. Exit of section 20 and long rounded section 21
A concentric die 23 is preferably dispensed between them. This die 23 can be rotated and has a crescent-shaped shaping segment 24 fixed to its inner surface for controlling concentric eyes. The rounded portion 21 tapers at the other conical funnel 22 to provide the desired exit size.

the resulting plastic blank at the fifth end has concentric eyes;
It would be advantageous to eliminate the S-shaped eye of the screw press, which is undesirable for many applications.

[Brief explanation of the drawing]

1 is a sectional view of an embodiment of the press according to the invention, which is configured as a rotor vacuum press and in which the stripping knife is forcedly controlled by an externally mounted control disk; FIG.
Figure a is a vertical cross-sectional view of the die of the press shown in Figure 1;
Figure b is a view of the die seen from the direction of the force indicated by the arrow nb in Figure 2a, and Figure 3 shows a stripping knife that is journalled at two rotation points;
3a is an enlarged view of part ma of FIG. 3; FIG. Figure 4a shows a press according to the invention in which the stripping knife is pressed towards the rotor by spring force and the contour of the rotor is in contact with two contact rollers provided at the outer edge of the stripping knife; Figures 5a, 5b, 5c and 5d are cross-sectional views of a rotor with differently configured cams. 2... Rotor housing, 3... Rotor,
4...Cam, 9...Material supply port, 13...Peeling knife, 15...Exit fan section agent Patent attorney Hikaru Esaki Yoshiyoshi agent Patent attorney Hikaru Esaki EEii: 1

Claims (1)

[Claims] 1. A material supply port (9) and a rotor (3), the rotor is provided in the rotor housing (2) and functions to generate pressure and transport the material, and at least two rotors are provided. In a press for manufacturing a plastic blank, in particular a ceramic cylindrical blank for insulators, the rotor ( 3) is bearing concentrically within the rotor housing (2) and has a stripping knife (13) at the upper end of the outlet sector (15).
), the stripping knife is forcibly controlled and moves up and down so as to barely touch the rotor during operation of the rotor. 2. The press for producing plastic blanks according to claim 1, characterized in that a gap of 0.05 to 2 mm always exists between the outer peripheral surface of the rotor and the stripping knife (13). 3. characterized in that the control device for the stripping knife (13) is provided outside the rotor housing (2);
The press for producing plastic blanks according to claim 1 or 2. 4. characterized in that the control device for the stripping knife (13) is provided inside the rotor housing (2);
The press for producing plastic blanks according to claim 1 or 2. 5. The stripping knife (13) is held by at least two guide rods (28), each of which carries at least one guide roller (17), and the control device of the stripping knife (13) A shaft (25) is provided, on which a control disc (30) is fixed, on which a guide groove (14) is milled, in which a guide roller (17) engages, and a control disc (30) is secured to the shaft. Claims 1 to 3 characterized in that the defining edge shows a projection of the rotor cross section and the shaft (25) of the control device rotates synchronously with the rotor.
A press for producing plastic blanks as described in any one of the above. 6. The stripping knife (13) is held by at least two guide rods (28), which guide rods are supported by springs (29).
characterized in that, along the edge of the stripping knife facing towards the rotor, the stripping knife comprises at least two contact rollers (26), which contact rollers slide along the rotor surface. , a press for producing a plastic blank according to any one of claims 1 to 3. 7. The stripping knife (13) is journalled at at least two rotation points (27), and the stripping knife (13) comprises at least two contact rollers (26) along the edge facing towards the rotor. A press for producing plastic blanks according to any one of claims 1, 2 and 4, characterized in that the contact roller slides along the rotor surface. 8. Press for producing plastic blanks according to claim 6 or claim 7, characterized in that two contact rollers are provided on the outer edge of the stripping knife. 9. The plastic blank production according to any one of claims 1 to 8, wherein the wedge angle of the wedge-shaped cam in the rotor rotation direction is larger than the wedge angle in the opposite direction to the rotor rotation direction. Press for. 10. The plastic blank production according to any one of claims 1 to 8, wherein the wedge angle of the wedge-shaped cam in the rotor rotation direction is smaller than the wedge angle in the opposite direction to the rotor rotation direction. Press for. 11. The press for producing a plastic blank according to any one of claims 1 to 10, characterized in that four cams are provided on the outer peripheral surface of the rotor (3). 12. Due to the shape of the stripping knife (13), the stripping edge of the stripping knife is pressed towards the rotor by the pressure of the conveyed material generated in the die (5). The press for producing a plastic blank according to claim 7. 13. The die (5) consists of a part (20) with a square inlet and a rounded outlet, followed by a rounded part (21), the square part being formed as a funnel with a side inclination angle of at least 30°; The press for producing a plastic blank according to any one of claims 1 to 12, characterized in that the part is much shorter than the round part. 14. The press for producing a plastic blank according to any one of claims 1 to 13, characterized in that the rotor housing (2) is cylindrical. 15. Between part (20) and part (21), part (23
), and the inner wall of this part (23) is provided with an eccentric shaping segment (24) for controlling the concentric eye. . 16. Dosing device for ceramic materials (9, 10, 1
1) and the circular rotor (3), a vacuum chamber (6) is provided, in which material can be supplied to the circular rotor (3) by means of a dosing roll (1) arranged in the vacuum chamber (6). The press for producing a plastic blank according to any one of claims 1 to 15, characterized in that: