Helical conveyor

• US 5,092,453 A
• Filed: 07/13/1990
• Issued: 03/03/1992
• Est. Priority Date: 11/10/1988
• Status: Expired due to Term

• Current Assignee: Spirac Engineering AB
• Original Assignee: Spirac Engineering AB
• Inventors: Bruke, Richard
• Primary Examiner(s): DAYOAN, DARRELL G
• Application Number:
  US07/557,156
• Time in Patent Office: 599 Days
• Field of Search: 198/657, 198/658, 198/659, 198/672, 198/673, 198/676
• US Class Current: 198/673
• CPC Class Codes: B65G 33/265 with a continuous helical surface flexible screws B65G33/16

Abstract

An apparatus for displacing material includes a transport thread composed of a central thread spiral and an outer thread. The outer thread spiral is fixed to one of the radially directed defining surfaces of the central thread spiral. The central thread spiral is dimensioned so as, without permanent deformation, to absorb at least the major portion of the mechanical forces occurring in the axial and radial direction of the transport thread. The outer thread spiral has an outer surface which faces away from the geometric centre axis of the transport thread and is of shorter extent in the axial direction of the transport thread and is located more distally from the center axis than the outer surface of the central thread spiral. By regulating the extent in the axial direction of the transport thread of the surface of the outer thread spiral turned to face the substrate, the abutment pressure of the transport thread will be adapted to the substrate in relation to the properties of the material being displaced.

Claims

1. Conveyor apparatus for material transport comprising a casing having an inlet end and a discharge end, a shaftless helical conveyor in said casing, said shaftless helical conveyor being rotatable around an axis of rotation, said shaftless helical conveyor including a central spiral member and and outer spiral member to said central spiral member, each of said central and outer spiral members respectively comprising a flat spiral blade having flat opposite side surfaces and inner and outer end surfaces, one of said flat side surfaces of said central spiral member being in face to face secured contact with one of said flat side surfaces of said outer spiral member in an arrangement in which the flat contacting side surfaces of the central and outer spiral members overlap and said outer spiral member extends radially outwardly of said central spiral member, said central spiral member having greater mass than said outer spiral member to resist, without residual deformation, mechanical forces applied to the conveyor, said outer end surface of said outer spiral member having an extent in the axial direction which is less than the axial extent of the central spiral member.

2. Conveyor apparatus as claimed in claim 1 wherein said central spiral member has a substantially rectangular cross-section.

3. Conveyor apparatus as claimed in claim 2 wherein said inner end surface of said outer spiral member forms a shoulder with the central spiral member.

4. Conveyor apparatus as claimed in claim 3 wherein said shoulder is inclined relative to said one surface of the central spiral member which is overlapped by the outer spiral member.

5. Conveyor apparatus as claimed in claim 4 wherein said shoulder extends at an obtuse angle relative to said one surface of the central spiral member.

6. Conveyor apparatus as claimed in claim 1 wherein said outer spiral member includes an outer edge portion disposed radially outwards of said central spiral member which tapers in narrowing fashion radially outward to said outer end of the outer spiral member.

7. Conveyor apparatus as claimed in claim 6 wherein said outer end surface of said outer spiral member extends parallel to a cylindrical surface of said casing and has a center coincident with the axis of rotation of the helical conveyor.

8. Conveyor apparatus as claimed in claim 1 wherein at least said outer end surface of said outer spiral member is made of abrasion resistant material.

9. Conveyor apparatus as claimed in claim 1 wherein said outer spiral member is made of steel which is harder than steel of said central spiral member.

10. Conveyor apparatus as claimed in claim 1 wherein said outer spiral member has a recess in which said central spiral member is seated.

11. Conveyor apparatus as claimed in claim 1 wherein said side surface of the central spiral member which overlaps the side surface of the outer spiral member faces in the direction of said discharge end of the casing whereas the later said side surface of the outer spiral member faces in the direction of said inlet end of the casing.

12. Conveyor apparatus as claimed in claim 1 wherein the inner end surfaces of said central and outer spiral members are both open to and face a central open passage in sad conveyor.