Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
  • B30B11/22—Extrusion presses; Dies therefor
  • B30B11/24—Extrusion presses; Dies therefor using screws or worms
  • B30B11/246—Screw constructions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/505—Screws
  • B29C48/507—Screws characterised by the material or their manufacturing process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/505—Screws
  • B29C48/507—Screws characterised by the material or their manufacturing process
  • B29C48/509—Materials, coating or lining therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/505—Screws
  • B29C48/59—Screws characterised by details of the thread, i.e. the shape of a single thread of the material-feeding screw
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/07—Flat, e.g. panels

Definitions

• the present invention relates to a method for producing a screw for an extruder, wherein the screw is provided at least in a section with a wear protection layer, wherein initially formed in a full bar a bed for the Verschl employsch ⁇ tz Anlagen, in which then the wear protection layer and finally forms the spaces between the screw flights.
• the screw also relates to a method for producing a screw, which is additionally provided in at least one other section with a sliding layer. It also affects such snails.
• EP 1614502 A - It is already known to line the housing of an extruder in those areas which are subject to increased wear, with a particularly wear-resistant material. These areas can be limited both axially and radially.
• EP 1614502 A -. is known, the wear-resistant material only in the compression zone and in the
• the extruder housing consists of the parts 1 and 2, which by means of flanges (not shown) are interconnected. Before connecting the two parts 1 and 2 together, you bring in part 2 from both sides of the wear-resistant material.
• the wear-resistant material is shown in FIG. 1 in the form of sleeve-shaped inserts 3, 4, that is not restricted in the radial direction. However, this does not matter that the wear-resistant material could also be present only in certain radial areas, as shown in FIG. 3 of EP 1614502 A -. is shown.
• Part 1 of the housing is provided for the intake and Vorkompressions- or preheating zone.
• the material is fed via a funnel (not shown).
• the insert 3 is located in the compression zone (where high mechanical wear occurs). Here the material is melted.
• the insert 4 is located in the metering zone (where high chemical wear occurs).
• the screw ensures a constant volume flow, which is then pressed through the extruder die. Between the inserts 3, 4 is in this embodiment, the decompression zone. In the decompression zone, a vacuum is applied so that the gases escape.
• the part 1 is usually made of nitriding steel and is e.g. 1.6 m long.
• the part 2 is e.g. 2.4 m long and is equipped with inserts 3, 4 made of (very hard) powder metallurgical steel.
• the part 2 itself can also consist of nitriding steel.
• Screws are usually coated with molybdenum.
• Molybdenum is a good friction partner for nitriding steel, it acts as a sliding layer, but it wears very fast in the field of powder metallurgical steel inserts.
• tungsten carbide is a good friction partner for the powder metallurgical applications, it acts as a wear protection layer, but it leads to rapid wear of nitriding steel. (Since snails are cheaper than the extruder housings, tungsten carbide is a very poor solution on nitriding steel screws because it often requires replacement of the extruder housings, and it is better if the screws wear out and need replacing more often, and the housings for them last longer.)
• screws are suitable for an extruder housing according to FIG. 1, they must be coated differently in the axial direction, as for example from DE 10161363 A -. is known.
• a helical groove is first milled into a rod.
• a tape with the desired layer is inserted.
• the entire surface of the screw flights is armored by a wear protection layer or with a
• molybdenum as a sliding layer is usually of lesser thickness (eg 0 , 4 mm) applied as tungsten carbide (eg 1 mm) as a wear protection layer.
• This object is achieved by a method of the type mentioned in the present invention, characterized in that the wear protection layer, e.g. made of tungsten carbide, applied by build-up welding and that forms the gaps with a lateral distance to the wear-resistant layer.
• the wear protection layer e.g. made of tungsten carbide
• a high-strength welded joint (a melt bond) is produced.
• the screw land is not fully occupied in the end with the wear protection layer, but the wear protection layer is also on the finished screw in a bed, that is laterally surrounded by material of the main body of the screw. This does not interfere with the use of the screw, but manufacturing technology has the advantage that the wear protection layer, such as tungsten carbide, must not be mechanically machined laterally. Nevertheless, you get a sharp edge.
• the preparation of the spaces is best done by a process which is referred to as "whirling".
• a cutter head is moved around the screw to be produced. This is much cheaper than milling, but this process is extremely difficult to machine extremely hard coatings.
• a wear-resistant layer is often a sliding layer necessary to reduce the wear of the housing in the non-hardened housing sections.
• a sliding layer for example molybdenum
• the base material heats up only moderately (eg to 150 ° C), so there is no danger that the screw will warp.
• thermal spraying in contrast to build-up welding, there is no fusion bond, but the adhesion is nevertheless sufficient.
• the problem is the location where the overlay adjoins the wear protection layer.
• the build-up welding namely, the base material of the screw is mixed with, for example, carbides, whereby the sliding layer does not adhere well at this point and easily breaks off.
• the sliding layer is usually much thinner, e.g. only half the thickness of the wear protection layer.
• a continuous bed, as in DE 10161363 A -. provided, is not optimal for these reasons.
• the screw in the section or in the sections where the overlay, eg made of molybdenum, to be applied to undersize brings, but it provides a lateral distance to the wear protection layer that then applied in the area with undersize the sliding layer and that finally brings the screw to the specified size. It can be seen - in contrast to DE 10161363 A -.
• Screws according to the invention of the type mentioned above are characterized in that the sliding layer, e.g. of molybdenum, a lateral distance to the wear protection layer, e.g. made of tungsten carbide. This lateral distance reduces the risk of the sliding layer breaking out. It is further favorable if the sliding layer in the end region, which faces the wear protection layer, is enclosed in a bed and has a rounded corner.
• FIG. 1 shows a housing of an extruder with different sections
• FIG. 2 shows a main body for a milled-bed screw for a wear protection layer
• FIG. Figure 3 shows this body, wherein in this bed the wear protection layer is applied.
• Fig. 4 shows this main body after the spaces between the screw flights have been formed;
• 5 shows this screw after the screw has been undersized in the area adjacent to the wear-resistant layer;
• Fig. 6 shows the finished screw;
• Fig. 7 shows a variant of Fig. 5; and
• FIG. 8 shows the corresponding variant of FIG. 6.
• the extruder housing of FIG. 1 consists of the parts 1 and 2, by means of
• Flanges (not shown) are interconnected. Before connecting the two parts 1 and 2 together, you bring in part 2 from both sides of the wear-resistant material.
• the wear-resistant material is shown in FIG. 1 in the form of sleeve-shaped inserts 3, 4.
• An associated screw is in the area of the inserts 3 and 4 with a
• Wear protection layer e.g. coated with tungsten carbide, but in the other areas with a sliding layer, for example with molybdenum.
• FIGS. 2-6 The production of such a screw is explained with reference to FIGS. 2-6.
• an axial region of the screw (or the main body of the screw) is shown, where the transition from tungsten carbide to molybdenum is (or should be).
• a wear protection layer 13 is then introduced by build-up welding (see Fig. 3).
• the hardfacing can be carried out manually, for larger series, of course, a welding robot can be used.
• Slip layer should be applied to undersize (e.g., 0.4 mm).
• the undersize should be exactly as large as the desired thickness of the sliding layer. It should be noted that here a lateral distance to the wear protection layer 13 is to be maintained, so that a web 19 stops.
• the sliding layer 18 (see FIG. 6) is brought into this area 17. Again, one again applies more than necessary (e.g., 0.5mm-0.6mm) and then grinds to the desired level (e.g., 0.4mm).
• the grinding to the nominal size is expediently carried out as the last step for the entire screw.
• FIG. 6 it is advantageous that the sliding layer 18 is separated from the wear-resistant layer 13 by a web 19, which consists of the basic material of the screw 11.
• the sliding layer 18 does not come with carbides so that the adhesion can not be affected by the carbides.
• the sliding layer 18 is laterally on the web 19, so that also the adhesion is improved.
• FIGS. 7 and 8 show a variant of FIGS. 5 and 6.
• the corner 20, which has an acute angle could be problematic. Such corners break out easily. Therefore, it is provided according to FIG. 7 that initially (eg over a half screw circumference) a bed 17 'is milled whose base has the desired undersize.
• a lateral web 21 is allowed to stand, and it necessarily follows (due to the radius of the milling cutter) a rounded corner 20 '.
• the sliding layer 18 has a rounded corner 20 '(see Fig. 8), which is bordered by the base material of the screw and is largely protected in this way from breaking.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Earth Drilling (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38561156

Family Applications (1)

Country Status (8)

Families Citing this family (9)

Family Cites Families (8)

• 2006
  • 2006-06-16 AT ATA1031/2006A patent/AT504385B1/de not_active IP Right Cessation
• 2007
  • 2007-05-01 TW TW096115443A patent/TW200810911A/zh unknown
  • 2007-06-06 CN CNA2007800222429A patent/CN101466523A/zh active Pending
  • 2007-06-06 EP EP07765328A patent/EP2043837A1/de not_active Withdrawn
  • 2007-06-06 JP JP2009514757A patent/JP2009539653A/ja active Pending
  • 2007-06-06 US US12/304,183 patent/US20090162470A1/en not_active Abandoned
  • 2007-06-06 CA CA002654011A patent/CA2654011A1/en not_active Abandoned
  • 2007-06-06 WO PCT/EP2007/055596 patent/WO2007144303A1/de active Application Filing

Non-Patent Citations (1)

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