Microstructured high friction surface for high friction to fabric, yarn, and fibers

Abstract

This invention is directed to an improved contact surface for manipulating articles wherein the microstructure included on the contact surface having a plurality of pillars spaced apart in the range of 200 m and 600 m, having a height in the range of 50 m and 1200 m, a width of in the range of 70 m and 300 m, a wall draft angle between 0 and 15, a density of in the range of 5,000 to 20,000 pillars per square inch, and a friction rating greater than 7. The contact surface can be included on a sewing machine feed dog, a glove, sporting equipment, firearm grip, hand rail, tool grip, tool handle, and a strap such as for a satchel or backpack.

Claims

1. A contact surface on a first article for manipulating a second article comprising: a microstructure arrangement included on the contact surface having a plurality of pillars spaced apart between 200 m and 600 m, having a height and width in a range of 90 m and 110 m and forming a generally square cross section so that said pillars are rigid to resist flexing and bending when contacting an article surface, a wall draft angle between 0 and 15, a density of between 5,000 to 20,000 pillars per square inch, and a friction rating greater than 7 in relation to the contact surface and an article surface; and, a static co-efficient of friction in the range of 0.78 to 3.56 and a dynamic coefficient of friction in the range of 0.74 to 4.08 as determined by friction test ASTM 1894.

2. The surface of claim 1 including a first row of pillars arranged in an offset configuration with a second row of pillars.

3. The surface of claim 1 wherein the pillars have a pitch in the range of 325 m and 375 m.

4. The surface of claim 1 wherein the pillars have a square cross-section.

5. The surface of claim 1 including a circular base included in each pillar.

6. The surface of claim 1 having a friction force against fabric in a horizontal direction and substantially no friction force in a vertical direction.

7. The surface of claim 1 having a non-linear horizontal friction against the article.

8. The surface of claim 1 wherein the pillars are arranged in a triangular lattice.

9. The surface of claim 1 including a lubrication coating on the pillars.

10. The surface of claim 9 wherein the lubrication coating in taken from the group consisting of: silicone oils, petroleum oils, mineral oils, PVD coating, PTFE coatings, diamond-carbon coatings, nitride, and carbide coatings.

11. A surface of claim 1 wherein the pillars have an area in the range of 63 cm.sup.2 and 242 cm.sup.2.

12. The surface of claim 1 wherein the first article is selected from the group consisting of: a feed dog, a glove, sporting equipment, rollers, tensioning rollers, firearm grip, tool handle, tool grip, and a strap.

13. The surface of claim 12 wherein the microstructure arrangement is attached on a substrate and the substrate is attached to the first article.

14. The surface of claim 12 wherein the strap is a backpack strap.

15. A contact surface on a first article for manipulating a second article comprising: a substrate disposed on the contact surface of the first article; a plurality of raised support structures disposed on said substrate, wherein each of said raised support structures has a generally pyramid shape; a microstructure arrangement included on said substrate having a plurality of pillars having a height in the range of 50 m and 1200 m, and a width in the range of 70 m and 300 m, wherein said pillars are disposed on top of said support structure; a wall draft angle in the range of 0 and 15, a static co-efficient of friction in the range of 0.83 to 1.70 and a dynamic coefficient of friction in the range of 0.80 to 1.39 as determined by friction test ASTM 1894 in relation to cotton fabric.

16. The surface of claim 15 wherein the first article is selected from the group consisting of: a feed dog, a glove, sporting equipment, firearm grip, tool grip, tool handle, and a strap.

17. The surface of claim 15 where the pillars are asymmetrical and have a trapezoid cross section.

Description

DESCRIPTION OF THE DRAWINGS

(1) The invention is better understood by referencing the following figures:

(2) FIG. 1 is an elevated view of aspects of the invention;

(3) FIG. 2 is a plan view of one row of certain pillars;

(4) FIG. 3 is a perspective view of aspects of the invention;

(5) FIG. 4 is a plan view of aspects of the invention;

(6) FIG. 5 is a plan view of one aspects of the invention;

(7) FIG. 6 is a plan view of aspects of the invention;

(8) FIG. 7 is a perspective view of aspects of the invention;

(9) FIG. 8 is a perspective view of aspects of the invention,

(10) FIG. 9 is a perspective view of the invention installed,

(11) FIG. 10A is a plan view of prior art;

(12) FIG. 10B is a plan view of aspects of the invention;

(13) FIG. 11 is an elevated view of aspects of the invention;

(14) FIG. 12 is a perspective view of aspects of the invention; and,

(15) FIG. 13 is a perspective view of aspects of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(16) Referring to FIG. 1, one embodiment of the present invention is shown by an elevated view of the microstructures that can be attached or otherwise secured to a surface used for manipulating fabrics. The features of the microstructure can include pillars 22a and 22b. These pillars can have a height (h) shown as 24 that is between 50 m and 1200 m. In one embodiment, his between 90 m and 110 m. In one embodiment, h is about 100 m. If the height is too small, the microsurface has unacceptable low friction against fabric. If the pillar height is too large the microstructures become subject to bending and wear life is reduced. In one embodiment, h is greater than 70 m.

(17) In one embodiment, the pillars can include a coating. The coating can be a lubricating coating. The lubricating coating can be silicone oils, petroleum or mineral oils, PVD-PTFE coating, diamond like carbon coatings, nitride, or carbide coatings.

(18) Each pillar can include a width (w) shown as 28 that is between 70 m and 300 m. In one embodiment, w is between 90 m and 110 m. In one embodiment, w is between 80 m to 100 m. In one embodiment, w is greater than 70 m. Each pillar can have a diameter of the cross section, if the pillar is circular, between 70 m and 300 m. In one embodiment, the diameter is between 90 m and 110 m. In one embodiment, the diameter is about 100 m. The pillars can include a side wall 26 that has a wall draft angle shown as 28 and designated . The wall draft angle can be between 0 and 15. In one embodiment, the wall draft angle is between 1 and 3. The pillars include a pitch (p) shown as 30, which is the distance between the center points of two pillars. In one embodiment, p is between 200 m and 600 m. In one embodiment, p is between 300 m and 350 m. In one embodiment the pillars can be perpendicular to the base surface with the central axis forming a 90 angle to the base. In other embodiments, the pillars can be tilted up to 30 from vertical. All of the pillars can be tilted in one direction or different pillars can be tilted in different directions and at different angles.

(19) In one embodiment, p is between 325 m and 375 m. In one embodiment, p is about 350 m. In one embodiment, the pillars can include an area between 63 cm.sup.2 and 242 cm.sup.2. If the pitch is too small the micro surface has unacceptable low friction against fabric. If the pitch is too large the pillars become subject to bending and wear life is reduced.

(20) In one embodiment, the area of the pillars is between 81 cm.sup.2 and 242 cm.sup.2. This range is particularly advantageous when the cross section of the pillars is square. In one embodiment, the area of the pillars is between 63 cm.sup.2 and 128 cm.sup.2. This range is particularly advantageous when the cross section of the pillars is circular.

(21) Referring to FIG. 2, the pillars can be arranged in rows shown as 32a through 32c. The row can be offset so that the pillars align vertically in alternating rows 32a and 32c and pillars of the intermediate row 32b are disposed between the pillars of the adjacent rows. The pillars are arranged on a rectangular lattice, a triangular lattice, asymmetrical lattice, repeating lattice pattern or variable distribution of spacing and arrangement.

(22) In one embodiment, the pillars include a cross section along A-A that is square as shown in FIG. 3. In one embodiment, the pillars can include a cross section along B-B that is circular. In one embodiment, the pillars can include a circular base 34. The pillars can be arranged so that they have a density between 2,000 and 20,000 pillars per square inch. Referring to FIG. 4, the pillars are shown in a triangular lattice 36. The microstructure may be made of pillars all of the same width or diameter, pitch and height, or the pillars may have a distribution of width or diameter, pitch and height. Referring to FIG. 5, the triangular lattice configuration can include pillars that are supported by raised structures 38 so that the top of the pillars generally are the same height at the top of the lattice. In one embodiment, the support for the pillars includes a pyramid structure having sides 40. Referring to FIG. 6, the pillars can include the microstructure disposed on the top of the pillars with the substrate or support surface 42 being smooth. The cross section of the pillars in this embodiment is asymmetrical and has a generally trapezoid shape with rounded corners. The offset configuration is shown in this embodiment.

(23) The present invention offers advantages over other material designed to enhance gripping. When the invention is compared to a popular technology micro-replication such as used on the gripping products provided by 3M, the following performance results are shown in Tables 2 through 5. In referring to the Fabric, the designations in the left column refer to a microstructures pattern disposed on the material. For example, ABS 002A is a pattern designated as 002A disposed on ABS.

(24) TABLE-US-00001 TABLE 2 Denim Compared Compared Compared Compared Fabric Feature Feature Feature Static to Smooth to Dynamic to Smooth to Against: width pitch height Co-Eff ABS SafeGuard Co-Eff ABS SafeGuard ABS 000 0 0 0 0.82 100% 50% 0.80 100% 50% ABS 002A 50 100 70 1.16 142% 72% 1.10 138% 69% ABS 008A 200 400 350 1.16 142% 71% 1.10 138% 69% ABS 009A 100 200 200 1.76 215% 108% 1.74 219% 108% ABS 009B 100 200 450 1.56 190% 96% 1.30 164% 81% ABS 009C 100 200 150 1.25 153% 77% 1.14 143% 71% ABS 021A 100 350 400 1.70 207% 105% 1.29 163% 81% ABS 021B 100 350 150 1.58 193% 97% 1.67 210% 104% Steel 80 290 120 2.87 350% 176% 2.89 364% 180% 021B Santoprene 100 350 150 2.21 269% 136% 2.13 268% 133% 021B Hytrel 100 350 150 1.92 234% 118% 1.76 221% 110% 021B Greptile/ 250 450 420 1.79 218% 110% 1.75 220% 109% Tegogrip SafeGuard 1.63 198% 100% 1.60 202% 100%

(25) TABLE-US-00002 TABLE 3 Stretch Knit Athletic Static Compared to Compared to Dynamic Compared to Compared to against: Co-Eff ABS SafeGuard Co-Eff ABS SafeGuard ABS 000 0.78 100% 34% 0.74 100% 89% ABS 002A 1.04 133% 45% 1.04 140% 334% ABS 008A 1.31 167% 56% 2.05 277% 138% ABS 009A 1.43 182% 61% 1.85 250% 129% ABS 009B 1.96 250% 84% 1.66 223% 202% ABS 009C 1.34 170% 57% 1.38 187% 82% ABS 021A 2.29 292% 98% 2.60 350% 37% ABS 021B 3.56 454% 153% 4.08 550% 51% Steel 021B 6.86 875% 294% 9.10 1226% 132% Santoprene 2.37 303% 102% 2.78 375% 69% 021B Hytrel 021B 2.53 323% 108% 2.67 360% 102% Greptile/ 1.89 241% 81% 1.79 241% 92% Tegogrip SafeGuard 2.33 298% 100% 2.72 367% 100%

(26) TABLE-US-00003 TABLE 4 Cotton Compared Shirting Fabric Static Compared to Compared to Dynamic Co- Compared to to Against: Co-Eff ABS 000 SafeGuard Eff ABS 000 SafeGuard ABS 000 0.83 100% 52% 0.80 100% 47% ABS 002A 1.24 149% 77% 1.14 143% 68% ABS 008A 1.10 132% 68% 1.10 137% 65% ABS 009A 1.42 171% 88% 1.39 174% 82% ABS 009B 1.51 181% 93% 1.31 164% 78% ABS 009C 1.29 155% 80% 1.13 141% 67% ABS 021A 1.70 205% 105% 1.35 169% 80% ABS 021B 1.57 189% 98% 1.33 166% 79% Steel 021B 2.69 324% 167% 2.60 325% 154% Santoprene 2.10 253% 131% 2.02 253% 120% 021B Hytrel 021 1.69 204% 105% 1.37 171% 81% Greptile/ 1.48 178% 92% 1.42 178% 84% Tegogrip SafeGuard 1.61 194% 100% 1.69 212% 100%

(27) TABLE-US-00004 TABLE 5 Compared Compared Compared Denim Fabric Static to Smooth to Dynamic to Smooth Compared to Against: Fabric Co-Eff ABS SafeGuard Co-eff ABS SafeGuard ABS 021B D 1.58 193% 97% 1.67 210% 104% K 3.56 454% 153% 4.08 550% 202% S 1.57 189% 98% 1.33 166% 79% Steel 021B D 2.87 350% 176% 2.89 364% 180% K 6.86 875% 294% 9.10 1226% 450% S 2.69 324% 167% 2.60 325% 154% Santoprene D 2.21 269% 136% 2.13 268% 133% 021B K 2.37 303% 102% 2.78 375% 138% S 2.10 253% 131% 2.02 253% 120% Hytrel 021B D 1.92 234% 118% 1.76 221% 110% K 2.53 323% 108% 2.67 360% 132% S 1.69 204% 105% 1.37 171% 81% Greptile/ D 1.79 218% 110% 1.75 220% 109% Tegogrip K 1.89 241% 81% 1.79 241% 89% S 1.48 178% 92% 1.42 178% 84% SafeGuard D 1.63 198% 100% 1.60 202% 100% K 2.33 298% 100% 2.72 367% 135% S 1.61 194% 100% 1.69 212% 100%

(28) The above comparisons also includes a walkway safety grip product, SafeGuard, which is a competitor of the product for 3M's Safety-Walk Slip-Resistant General Purpose Tread. Also tested were polymer materials and steel. The friction test is based on ASTM D1894. The Santoprene can have a hardness of 75 (Shore A). This test is a sled type test where the polymer or steel samples were attached to the sled and were all 5 cm5 cm size. Weight of 200 grams was used on the sled. The fabrics were strapped over a base plate and the sled drags across the fabric. Three fabrics were tested: denim, stretch knit athletic jersey fabric and cotton shirting fabric.

(29) In operation, the microstructures can be manufactured onto the fabric contact surface or subsequently attached to the contact surface. A substrate can have microstructures placed on the substrate on one side and an adhesive placed on the other side to allow the substrate to be secured to a contact surface. The contact surface can be made from material taken from the group consisting of rubber, plastic, brass, bronze, steel, titanium, carbides, or ceramics. The microstructures can be made by any technique used to form plastic, rubber metal, or ceramic such as lithography, molding, NC machining, electrical discharge machining, molten metal casting, powder metal compaction, metal injection molding, or similar techniques well known to those familiar with the art. In one embodiment, the fabrication technique is to make a master pattern by lithography on a silicon wafer; to transfer the pattern to a rubber sheet; to use the rubber sheet to mold metal injection molding compound; to sinter the metal injection compound to make steel, titanium molds, or metal parts. The molds are then used to mold rubber, plastic, ceramic, powdered metal or metal injection compound articles.

(30) In one application, the contact surface is disposed on a feed dog for sewing machine 44 as shown in FIG. 7. The fabric travels generally in a direction shown as 46 and the microstructures on the feed dog grip to move the fabric in direction 46. The microstructures do not grip the fabric when moving in a direction opposite that of 46.

(31) Referring to FIG. 8, a feed dog 10 is shown having risers 12a through 12d that can protrude through the pressure plate 100 (FIG. 8) of the sewing machine 102. The risers can include a contact surface 14 that includes microstructures 16 and that contacts the fabric to advance the fabric under the presser feet 104 (FIG. 9) and across the pressure plate. The microstructures provide for a friction force to be applied when the contact surface moves horizontally across the fabric in a direction shown as 18 and has substantially no friction force in a vertical direction shown as 20. Feed dogs using the microstructured contact surface have high friction against fabric and allow use of lower pressure on the presser feet of sewing machines. The improved feed dogs achieve higher speed and higher productivity sewing.

(32) Referring to FIGS. 10A and 10B, the feed dogs 10 (FIG. 10B) of the current invention can be used to replace conventional sewing feed dogs 48 (FIG. 10A) without modification of the sewing machines. With the invention installed, the fabric is more accurately and consistently fed, life of the feed dog is increased, and consistency of the resulting seam is improved. Feed dogs with the microstructures described herein have high friction against fabric that is uniform in any direction across the fabric surface. Thus the sewing dogs may be used in automated and robotic fabric sewing or handling equipment that must move the fabric in any horizontal direction.

(33) In comparing the microstructure of the present invention to that of the convention feed dogs, the advantages of the present invention are notable. In a friction test designed to measure the tactile response of a user, 2 inch2 inch squares of molded plastic or formed steel with the microstructures were placed against a fabric by hand and attempted to move laterally. The perceived force of the test subjects was measured on a scale of one to ten and compiled in the following chart.

(34) TABLE-US-00005 Feature Friction Friction width (w) Feature rating rating or Pitch height Cotton polyester diameter Feature (p) Lattice (h) shirt knit Pattern # m shape m geometry m (1 to 10) (1 to 10) 021A 100 square 350 triangular 400 10 10 021B 100 square 350 triangular 150 10 10 Smooth 1 1 steel Singer 3 3 commercial feed dog

(35) Fabrics that were tested to obtain the above results included paper towels, foam rubber, EVA foam, and Neoprene wet suit material. The microstructures when applied to different contact surfaces would exhibit the same results against the same materials.

(36) Referring to FIG. 11, the contact surface can be a glove 50. There can be several contact surfaces on the glove that can include the fingers, finger tips 52a through 52b, thumb, thumb pad 54, and palm 56. The palm area can have microstructures attached generally to the entire palm area or portion of the palm area. In one embodiment, the microstructures are attached in a palmar area 58 defined toward the distal end of the hand generally above where the distal palmar crease would be superimposed. The microstructures can be attached in a thenar area 60 defined between the thumb and where the thenar crease would be superimposed. The microstructures can be attached in a hypothenar area 62 defined between the outer edge of the hand and where the thenar crease and proximal palmar crease would be superimposed. The placement of the microstructures can be one generally the entire palm side of the glove or selected portions of the glove.

(37) Referring to FIG. 12, the contact surface can also be included in straps for carrying articles such as a briefcase or backpack 64. It is a common complaint that the straps 66 slip off the shoulder with use. The strap typically contacts the shoulder of the wearer and therefore the fabric of the wearer's clothing. The contact surface 68 of the strap can include microstructures that contact the fabric of the wearer's clothing that prevent the strap from slipping in a direction shown generally as 68 or 69. As the microstructures cause a unidirectional grip, the strap can slip onto the shoulder in a direction opposite 68 or 69 for wearing without undue friction impeding proper placement of the straps. The microstructures can be disposed at the top of the underside of the strap and can partially or completely to the lower end of the strap. In one embodiments, the contact surface can be on a medical device, or fitness device that is worn against clothing or that is disposed between the clothing and skin.

(38) Referring to FIG. 13, the contract surface can be the grip of an article such as a bat 70, cooking utensil, workout weights, sporting goods, tools (including hand tools, power tools, and the like), firearm, hand rail, ladder, handle, roller, tensioning rollers and the like. The rollers can also be used in high speed manufacturing and processing of textiles and fabrics. In one embodiment, the microstructures are disposed on a substrate and the substrate is attached to the article. Concerning rollers, the microstructures can be attached to a sheet that is then wrapped around a roller. The roller is used to feed textiles and fabrics for both the manufacturing process and processing process. For example, when a fabric is exiting a manufacturing machines, the roller tension the fabric so that the fabric is rolled around a core with tension which is advantageous when rolling fabric for storage, transportation and use.

(39) The microstructures can be deposed in an area 72 that is typically gripped with the user wearing fabric gloves. The gloves can be traditional gloves without microstructures such as batting gloves, work gloves, utility gloves, and the like. With the microstructures, the contact between the contact surface and the glove can have increased friction thereby improving the grip even in wet conditions.

(40) In advantage of the present invention is to improve the wearer's experience of articles when the article come is direct contact with the skin. Such articles include breathing masks, watch bands, fitness devices, mouth pieces, shoulder pads, shin guards, and the like. In embodiment of the present invention provides for a pleasant and nice feel and friction against skin, allows circulation and cross circulation of air, allows for evacuating sweat and other fluids, and promoting comfort against the skin.

(41) In one embodiment, the microstructures can be placed on the inner surface of footwear so that there is increased grip between the shoe and a sock. This results in the footwear feeling more secure to the wearer as the shoe does not slip against the sock as much as with a traditional shoe. The microstructure can be placed on a contact surface that is contained to the underside of the tongue.

(42) The advantages of the invention have also shown to be useful for items where the contact surface contacts skin, rather than fabric. Some applications that benefit from this advantage of the present invention include breathing masks, watch bands, fitness devices and other items that come in direct contact with skin. The microstructures contact surface in this embodiment, provides for a pleasant feel, provides for friction against skin, allows circulation and cross circulation of air, allows for the evacuating of sweat and promotes comfort against the skin.

(43) While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

(44) Unless specifically stated, terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. Likewise, a group of items linked with the conjunction and should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as and/or unless expressly stated otherwise. Similarly, a group of items linked with the conjunction or should not be read as requiring mutual exclusivity among that group, but rather should also be read as and/or unless expressly stated otherwise.

(45) Furthermore, although items, elements or components of the disclosure may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated. The presence of broadening words and phrases such as one or more, at least, but not limited to, or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent.