Structural assemblies using integrally molded, and welded mechanically locking z-pins

• US 20050042023A1
• Filed: 08/20/2003
• Published: 02/24/2005
• Est. Priority Date: 08/20/2003
• Status: Abandoned Application

• Current Assignee: Northrop Grumman Corporation
• Original Assignee: Northrop Grumman Corporation
• Inventors: Jones, Steve R.
• Application Number:
  US10/644,424
• Publication Number:
  US 20050042023A1
• Time in Patent Office: Days
• US Class Current: 403/267
• CPC Class Codes: B29C 65/564 hidden in the joint, e.g. dowels or Z-pins B29C65/603 takes precedence
• CPC Class Codes: B29C 65/58 Snap connection
• CPC Class Codes: B29C 65/76 Making non-permanent or releasable joints
• 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 66/30321 making use of protrusions belonging to at least one of the parts to be joined
• CPC Class Codes: B29C 66/30325 making use of cavities belonging to at least one of the parts to be joined
• CPC Class Codes: B29C 66/30341 non-integral with the parts to be joined, e.g. making use of extra elements B29C65/562 takes precedence
• CPC Class Codes: B29C 66/45 Joining of substantially the whole surface of the articles methods or apparatus for laminating B32B37/00
• 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: B29C 66/721 Fibre-reinforced materials B29C66/729 takes precedence
• CPC Class Codes: B29K 2023/06 PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/065 HDPE, i.e. high density polyethylene
• CPC Class Codes: B29K 2023/0683 UHMWPE, i.e. ultra high molecular weight polyethylene
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2079/08 PI, i.e. polyimides or derivatives thereof
• CPC Class Codes: B29K 2083/00 Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as moulding material
• CPC Class Codes: F16B 11/006 by gluing gluing of plastics material B29C65/48
• CPC Class Codes: F16B 5/07 by means of multiple interengaging protrusions on the surfaces, e.g. hooks, coils,
• CPC Class Codes: Y10T 403/472 including mechanical interlock

Abstract

A structure is provided which includes first and second layers. The first and second layers are attached to each other by embedding or otherwise attaching at least one mechanically locking z pin to the first layer and then subsequently joining the protruding portion of the z pin to the second layer prior to the second layer being processed to a fully cured state. Alternatively, the z pin material is injected into a cavity formed in the first and second layer and then brought to a fully cured state. The z pin may have physical characteristics such as orientation, melting point and hardness as a function of the physical characteristics of the first and second layer and the forces subjected upon the first and second layers. For example, the z pin may define a longitudinal axis and be embedded within the first and second layers in alignment with an applied force subjected on the first and second layers. This ensures that the z-pin is subjected primarily to tensile forces which allows designs to better control the failure mode of the attached first and second layers.

Claims

1. A structure comprising:

a. a first layer;

b. a second layer adjacent to the first layer; and

c. at least one z-pin embedded within the first and second layers to attach the first and second layers, the z-pin embedded therein defines a pull out force with respect to the first layer less than a pull out force with respect to the second layer, each z-pin having at least two radially extending flanges with at least one flange embedded within the first layer to greater depth compared to a depth to which the flange section is embedded within the second layer to compensate for the lower pull out force of the z-pin from the first layer compared to the pull out force of the z-pin from the second layer.

2. The structure of claim 1 wherein each layer and z-pin defines a melting temperature, and the melting temperature of the z-pin is greater than the melting temperatures of the layers to allow the z-pin to be casted into the first and second layers.

3. The structure of claim 1 wherein the first layer is manufactured from material selected from the group consisting of metal, ceramic, organic material, inorganic material, organic material with reinforcement fibers, organic material without reinforcement fibers, inorganic material with reinforcement fibers, inorganic material without reinforcement fibers, ceramic, and graphite epoxy.

4. The structure of claim 1 wherein the second layer is manufactured from material selected from the group consisting of metal, ceramic, organic material, inorganic material, organic material with reinforcement fibers, organic material without reinforcement fibers, inorganic material with reinforcement fibers, inorganic material without reinforcement fibers, ceramic, and graphite epoxy.

5. The structure of claim 1 wherein the first and second layers are manufactured from identical materials.

6. The structure of claim 1 wherein the z-pins embedded within the first layer have a greater number of flange sections embedded therein compared to a number of flange sections embedded within the second layer to compensate for the lower pull out force of the z-pin from the first layer compared to the pull out force of the z-pin from the second layer.

7. The structure of claim 1 wherein the z-pin has at least three radially extending flanges with a center flange having a cylindrical peripheral edge disposed at interface surfaces of the first and second layers to evenly distribute shearing forces created by the first and second layers on the center flange.

8. The structure of claim 1 wherein an applied force is subjected on the structure and each z-pin defines a longitudinal axis aligned with the applied force to maximize the load carrying ability of the z-pin.

9. The structure of claim 1 wherein the first layer, second layer and z-pin define respective densities, and the z-pin density is lower than the densities of the first and second layers to reduce a density of the structure with z-pins compared to a density of the structure without z-pins.

10. The structure of claim 1 wherein the first layer, second layer and z-pin define respective hardnesses, and the z-pin hardness is lower than the hardness of the first and second layers to allow the z-pin to be removed from the first and second layers.

11. The structure of claim 1 wherein the first layer, second layer and z-pin define respective coefficients of thermal expansion, and the coefficients of thermal expansion of the first layer, second layer and z-pin(s) may be equal to limit stresses between the z-pin and respective first and second layers.

12. The structure of claim 1 further comprising a strip disposed between the first and second layers wherein the strip has embedded therein the z-pin flanges protruding from respective interface surfaces of the first and second layers.

13. A structure comprising:

a. a first layer defining an interface surface and having at least one depression, each depression configured as a female mating flange of a z-pin;

b. a second layer defining an interface surface with at least one nub being unitary with the second layer, each nub configured as at least one flange of the z-pin.

14. The structure of claim 13 wherein each layer defines a melting temperature and the melting temperature of the second layer is greater than the melting temperature of the first layer to allow the nub to be casted within the depression of the first layer.

15. The structure of claim 13 wherein the first layer is manufactured from material selected from the group consisting of metal, ceramic, organic material, inorganic material, organic material with reinforcement fibers, organic material without reinforcement fibers, inorganic material with reinforcement fibers, inorganic material without reinforcement fibers, ceramic, and graphite epoxy.

16. The structure of claim 13 wherein the second layer is manufactured from material selected from the group consisting of metal, ceramic, organic material, inorganic material, organic material with reinforcement fibers, organic material without reinforcement fibers, inorganic material with reinforcement fibers, inorganic material without reinforcement fibers, ceramic, and graphite epoxy.

17. The structure of claim 13 wherein the first layer defines a first layer strength and the second layer defines a second layer strength stronger than the first layer strength, and a nub embedded within the first layer defines a pull out force as a function of a number of flanges embedded therein and the first layer strength, and the nub unitary with the second layer defines a pull out force as a function of the second layer strength, the nub having a sufficient number of flanges such that the pull out force of the nub embedded within the first layer is less than the pull out force of the nub for directing a failure mode of the structure to the first layer.

18. The structure of claim 13 wherein the nub has a base flange configured as a cylindrical peripheral edge, and the base flange is disposed at interface surfaces of the first and second layers to evenly distribute shearing forces created by the first and second layers on the base flange.

19. The structure of claim 13 wherein the first layer and second layer define respective coefficients of thermal expansion, and the coefficients of thermal expansions of the first and second layers are equal to limit stresses between the nub and the first layer.

20. A method for limiting delamination between attached first and second layers, the method comprising step a) of embedding a plurality of z-pins into an interface surface of the first layer, and embedding a plurality of z-pins into an interface surface of the second layer, each z-pin having at least two radially extending flanges, at least one flange section being embedded into respective first and second layers, and at least one flange sections protruding externally from the interface surfaces of respective first and second layers.

21. The method of claim 20 further comprising step b) of inserting the flanges protruding externally from the interface surfaces of the first and second layers into the interface surfaces of the second and first layers, respectively.

22. The method of claim 20 further comprising step b) of inserting the flanges protruding externally from the interface surfaces of the first and second layers into a strip.

23. The method of claim 22 wherein the plurality of z-pins embedded into the first and second layers have z-pins embedded within the first layer which are offset with the z-pins embedded within the second layer.

24. A method of embedding z-pins within first and second layers, the method comprising:

a. forming female flange sections within the first and second layers with a channel connected to each of the female flange sections;

b. aligning the female flange sections of the first and second layers to each other;

c. filling liquid z-pin material into the aligned female flange sections of the first and second layers through the channel; and

d. solidifying the liquid z-pin material.