MACHINE FOR THE PREPARATION AND EXTRUSION OF PLASTICS

• US 3,825,236 A
• Filed: 11/20/1972
• Issued: 07/23/1974
• Est. Priority Date: 11/24/1971
• Status: Expired due to Term

• Current Assignee: Dieter Kurth, Jurgen Hussmann
• Original Assignee: Dieter Kurth, Jurgen Hussmann
• Inventors: Hussmann, Jurgen, Kurth, Dieter
• Primary Examiner(s): Hornsby, Harvey C.
• Assistant Examiner(s): Coe, Philip R.
• Application Number:
  US05/307,803
• Time in Patent Office: 610 Days
• Field of Search: 259/191,192,193,6,21,41,104,9,10 425/204,202,208,209
• US Class Current: 366/76.1
• CPC Class Codes: B29B 7/485 with three or more shafts provided with screws
• CPC Class Codes: B29C 48/03 characterised by the shape of the extruded material at extrusion
• CPC Class Codes: B29C 48/395 using screws surrounded by a cooperating barrel, e.g. single screw extruders
• CPC Class Codes: B29C 48/435 Sub-screws
• CPC Class Codes: B29C 48/44 Planetary screws
• CPC Class Codes: B29C 48/63 having sections without mixing elements or threads, i.e. having cylinder shaped sections
• CPC Class Codes: B29C 48/67 having incorporated mixing devices not provided for in groups B29C48/52 - B29C48/66
• CPC Class Codes: B29C 48/68 Barrels or cylinders

Abstract

The machine includes a planetary roll extruder, a single-screw feeding device in advance of the extruder and a single-screw extrusion press following the extrusion. The feeding device includes a cylinder and a feed hopper, and the feeding device, the extruder and the extrusion press are combined by having a common shaft extending therethrough. The common shaft, in the range of the feeding device and of the extrusion press, is designed as a screw shaft and, in the range of the planetary roll extruder, is designed as a central or '"'"''"'"''"'"''"'"'sun'"'"''"'"''"'"''"'"' shaft. The feeding device is constructed as a feed press, and at least one of the planetary spindles of the extruder is axially fore-shortened relative to the other planetary spindles to form a revolving receiving chamber for the material supplied by the feed press. The feed press is constructed to have a feed performance exceeding the receiving capacity of the planetary roll extruder and thus of the single-screw extrusion press. Preferably every other planetary spindle of the extruder is axially fore-shortened to form a receiving chamber.

Claims

1. In a machine for the preparation and extrusion of plastics, of the type including a planetary extruder with a cylinder, a central shaft, and planetary spindles rotatable about respective axes, the spindles being helically geared to the central shaft and to the cylinder for revolution of the planetary spindles around the central shaft, and a single-screw feeding device in advance of the extruder and aligned therewith, with the feeding device including a cylinder and a feed hopper, and a common shaft extending through the feeding device cylinder and the extruder, the common shaft, in the range of the feeding device, being designed as a screw shaft and, in the range of the planetary extruder, as the central shaft thereof:

the improvement comprising, in combination, the single thread of said screw shaft having a clearance, with the cylinder of said feeding device, sufficient only to provide for rotation of said screw shaft, and extending from said feed hopper to said planetary extruder whereby, during rotation of said common shaft, material supplied through said feed hopper is plasticized in said feeding device and pressed toward said planetary extruder;

at least one planetary spindle being axially shorter than the other planetary spindles to form a rEvolving receiving chamber, at its end adjacent said feeding device, for the material supplied by said feeding device acting as a feed press.

2. In a machine for the preparation and extrusion of plastics, the improvement claimed in claim 1, in which said cylinder of said feed press is formed with grooves extending longitudinally of its inner surface at an angle of 0* to the axis of the screw shaft of said feed press.

3. In a machine for the preparation and extrusion of plastics, the improvement claimed in claim 2, in which said longitudinally extending grooves define a material flow volume which is from 5 to 10 percent of the material flow volume defined by the cylinder of said feed press and a single turn of the thread of the screw shaft of said feed press.

4. In a machine for the preparation and extrusion of plastics, the improvement claimed in claim 1, including a single-screw extrusion press following said planetary extruder and aligned therewith;

said common shaft also extending through said single-screw extrusion press and, in the range of said extrusion press, being designed as a screw shaft.

5. In a machine for the preparation and extrusion of plastics, the improvement claimed in claim 4, in which said single-screw extrusion press comprises a cylinder having said common shaft extending therethrough;

the cylinder of said feeding device and said screw shaft extending therethrough defining a material processing and feeding volume greater than the receiving volume defined by the cylinder, central shaft and planetary spindles of said planetary extruder and the volume defined by the cylinder and the screw shaft of said extrusion press;

whereby, during rotation of said common shaft, the rate of supply of material from said feeding device to said planetary extruder is in excess of the rate of extrusion of the material by said planetary extruder and the rate of feeding of the material by said extrusion press so that said planetary extruder, during rotation of said common shaft, is continuously supplied with plasticized material under pressure.

6. In a machine for the preparation and extrusion of plastics, the improvement claimed in claim 5, in which the screw shaft of said feed press has a length which is at least 2D where D is the overall exterior diameter of the screw shaft of the feed press.

7. In a machine for the preparation and extrusion of plastics, the improvement claimed in claim 6, in which the screw shaft of said feed press has a length which is 3D.

8. A machine for the preparation and extrusion of plastics, the improvement claimed in claim 5, in which the thread of the screw shaft of said feed press has a substantially rectangular cross section, and the screw shaft of said feed press has a tapering core.

9. In a machine for the preparation and extrusion of plastics, the improvement claimed in claim 1, in which, considered, circumferentially of the central shaft of said planetary extruder, alternate planetary spindles are axially foreshortened at their ends adjacent said feed press to form respective receiving chambers for the material supplied by said feed press.

10. In a machine for the preparation and extrusion of plastics, the improvement claimed in claim 9, in which said planetary spindles have cores with helical gear threads extending radially from the cores;

the alternate planetary spindles being foreshortened, relative to the other planetary spindles therebetween, by an amount corresponding to the spindle core diameter in the range of d/2 to d, where d is the spindle core diameter.