Method and device for holding together an electronically non-conductive stack of objects

• US 8,242,411 B2
• Filed: 07/07/2006
• Issued: 08/14/2012
• Est. Priority Date: 07/07/2005
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Vreeman, Johan Hendrik, Ten Tije, Gerrit Hendrik
• Primary Examiner(s): Yuen, Henry
• Assistant Examiner(s): Maye, Ayub
• Application Number:
  US11/482,118
• Publication Number:
  US 20070029297A1
• Time in Patent Office: 2,230 Days
• Field of Search: 219/148, 219/81, 219/82, 219/84, 219/79, 219/119, 219/106, 219/91.21, 361/225, 361/230, 361/233
• US Class Current: 219/148
• CPC Class Codes: B29C 65/008 making use of electrostatic charges holding means using electrostatic forces to hold at least one of the parts to be joined B29C65/7852
• CPC Class Codes: B29C 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 65/7855 Provisory fixing
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/432 for making tubular articles or closed loops, e.g. by joining several sheets B29C66/547 takes precedence; bending and joining sheets at right angles to the longitudinal axis of the article being formed and joining the edges B29C53/38; for making hollow articles or hollow preforms
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29K 2075/00 Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
• CPC Class Codes: B29L 2031/7128 Bags, sacks, sachets tea bags B29L2031/7122; medical bags B29L2031/7148
• CPC Class Codes: B65H 2301/4223 Pressing piles
• CPC Class Codes: B65H 2301/5132 Bringing electrostatic charge
• CPC Class Codes: B65H 2601/252 Collapsing, e.g. of piles

Abstract

A method for holding together an electrically non-conductive stack of objects, such as a stack of magazines or foil strips includes forming the stack of objects; and applying to one side of the stack a static polarity with a planar, semi-conductive electrode.

Claims

1. Method of holding together electrically non-conductive objects, comprising:

forming a stack of the electrically non-conductive objects; and

applying to a side of the stack a static polarity with a planar electrode to electrostatically holding the objects together;

wherein the planar electrode comprises

a conductive layer, and

a layer of semi-conductive material that covers the conductive layer and defines an outermost surface of the planar electrode; and

wherein said applying comprises;

connecting the conductive layer to a static electricity source, and

directly contacting the semi-conductive material with said side of the stack to apply static electricity from the static electricity source, via the conductive layer to the semi-conductive material, and then to said side of the stack;

wherein

the semi-conductive material is elastically deformable,

the semi-conductive material deforms upon direct contact with said side of the stack to ensure close contact and homogeneous transfer of the static electricity to the electrically non-conductive objects in the stack,

the semi-conductive material springs back to an original form thereof when the direct contact between the stack and the semi-conductive material is ended, and

said conductive layer is free of direct contact with the stack of objects when the semi-conductive material is in direct contact with said side of the stack.

2. Method as claimed in claim 1, wherein

the semi-conductive material has a specific resistance of 10³−

10¹² ohm.

3. Method as claimed in claim 2, wherein

the semi-conductive material is impregnated or doped polyurethane foam.

4. Method as claimed in claim 1, further comprising

reciprocating the electrode toward and away from the stack of objects, while said stack is being continuously transferred along a transfer path, to apply the static electricity to said stack at a plurality of locations intermittently arranged along said path, to thereby electrostatically holding the objects together at said locations while leaving spaces among said objects in regions between adjacent said locations.

5. Method as claimed in claim 4, further comprising

welding the objects together at said locations where the objects have been electrostatically held together.

6. Device for holding together an electrically non-conductive stack of objects, said device comprising

a placing location for the stack of objects;

and

at least one planar electrode for applying a static polarity to a surface of the stack;

wherein the planar electrode includes;

a conductive layer for electrical connection to a static electricity source, and

a layer of semi-conductive material that covers the conductive layer and defines an outermost surface of the planar electrode for directly contacting the surface of the stack and transferring static electricity from the static electricity source, via the conductive layer to the semi-conductive material, and then to said surface of the stack;

wherein

the semi-conductive material is elastically deformable,

the semi-conductive material is configured to deform upon direct contact with said surface of the stack to ensure close contact and homogeneous transfer of the static electricity to the electrically non-conductive objects in the stack,

the semi-conductive material is configured to spring back to an original form thereof when the direct contact between the stack and the semi-conductive material is ended, and

said conductive layer is configured to be free of direct contact with the stack of objects when the semi-conductive material is in direct contact with said surface of the stack.

7. Device as claimed in claim 6, further comprising a conveyor belt for transferring the stacked objects from a station at the placing location where the objects are to be placed in a stack to a static electricity application location under the electrode.

8. Device as claimed in claim 7, further comprising a counter-electrode, which comprises a roller disposed below the conveyor belt and opposite the electrode, for applying a counter-polarity to a bottom surface of the stack.

9. Device as claimed in claim 7, further comprising a pair of counter-electrodes disposed on opposite sides of the belt for contacting and applying a counter-polarity to lower portions of side surfaces of the stack.

10. Device as claimed in claim 7, wherein the planar electrode is moveable toward and away from a transfer path of the conveyor belt for contacting and applying static electricity to a top surface of the stack of objects.

11. Device as claimed in claim 7, further comprising a welding device positioned adjacent the conveyor belt downstream of the electrode for welding the stacked objects in portions the stacked objects are held together by static electricity applied by the electrode.

12. Device as claimed in claim 10, wherein the planar electrode is further moveable along the transfer path of the conveyor belt.

13. Device as claimed in claim 7, wherein the conveyor belt is grounded to define a counter-electrode for applying a counter-polarity to a bottom surface of the stack.

14. Device as claimed in claim 6, wherein the semi-conductive material has a specific resistance of 10³−

10¹² ohm.

15. Device as claimed in claim 14, wherein the semi-conductive material is impregnated or doped polyurethane foam.

16. Device as claimed in claim 14, wherein the semi-conductive material is one selected from the group consisting of woven materials, and non-wovens of fibers.

17. Device as claimed in claim 6, wherein the semi-conductive material has a specific resistance of greater than 10¹⁰ and lower than 10¹² ohm.