Patent Application
20090266280
The present application claims priority to the Apr. 29, 2008 filing date of U.S. provisional patent application, Ser. No. 61/048,743.
The present invention relates to the manufacture of tufted fabrics, and particularly to a double acting gate apparatus to allow a looper to tuft either loop pile or cut pile stitches.
In the field of tufting, there have been a variety of efforts made to enable both cut pile and loop pile tufts or bights of yarn to be placed in the same row of stitches. In some instances, the structures utilized for this purpose did not allow effective control of the height of stitches and, for instance, the cut pile stitches might always be of greater height than the loop pile stitches. The use of pivoting gate structures on the loopers was proposed in Jolley, U.S. Pat. No. 4,134,347 and Crumbliss, U.S. Pat. No. 4,353,317.
Later sliding gate structures were proposed as typified by Bennett, U.S. Pat. No. 6,155,187. When properly implemented, sliding gate structures may provide rapid response and avoid moving the entire pneumatic activation assembly with the loopers. However, Bennett taught the use of internal biasing elements in pneumatic cylinders and the use of blocks of cylinders to improve efficiencies in assembly. In practice, the use of internal biasing elements limits the size and corresponding force that the biasing elements may provide. In turn, this limits the speed with which the gate can return to the open position after pressure to its corresponding pneumatic cylinder is stopped. Furthermore, the internal biasing elements are not visible to inspection and if rust begins to form due to moisture in the cylinder, for instance, there will be no way to detect the problem until performance degrades to the point where defective carpet patterns are produced, with resulting waste carpet and the need to replace an entire cylinder block rather than merely a spring or biasing element.
A sliding gate structure utilizing an external spring was proposed in Kilgore, U.S. Pat. No. 7,222,576. Other efforts to improve the operation of gated loopers have focused on the gate assembly itself as in Johnston, U.S. Publication No. 2005/0109253.
The spring return gates suffer from a number of shortcomings, regardless of whether the spring is internally or externally placed. Principal among these shortcomings are the durability of the springs and the fact that a spring's biasing force changes over the range of compression of the spring. Thus, the durability of springs manifests itself over time as the spring material fatigues and the biasing force provided by the springs to slide the gate structures to the return position is diminished. Eventually, springs will even break from mechanical fatigue.
In addition, the further a spring is compressed, the greater the biasing force of the spring acting against the compression. Thus, if the spring is oriented to return the gate to retracted position, the spring is nearly fully compressed when the gate reaches its extended position. As the gate approaches the fully extended position, the spring is more fully compressed and the biasing force acting against the air pressure of a pneumatic cylinder increases. Due to friction between moving parts and the increased biasing force acting against the pneumatic pressure, some gates stick or fail to reach a fully extended position. Similarly, the further a spring is decompressed, the less biasing force the spring possesses. As the spring force gets weaker, it may fail to force all of the air in the cylinder to exhaust, causing the gate to stick before returning the gate to the fully retracted position.
It is desirable to address these shortcomings of spring biased gate structures without significantly increasing the cost or complexity of the gate control mechanisms.
Therefore, it is a primary object of the invention to provide an improved sliding gate structure for use in tufting both loop pile and cut pile stitches from yarns seized by the same looper.
It is another object of the invention to provide a double acting, or two way, pneumatically activated sliding gate structure to move the gates from their open and unactivated position to their closed and activated positions and back again.
It is yet another object of the invention to provide a double acting pneumatic drive mechanism for a sliding gate structure that tends to return the gates to their open and inactivated position.
It is further object of the invention to provide an array of pneumatic cylinders and corresponding activated sliding gates in a compact form so as to be effectively employed with narrow gauge needle configurations according to the present invention.
It is a still further object of the invention to provide an array of double acting pneumatic cylinders in a cost effective structure that does not add unnecessary complexity to the sliding gate mechanism and controls.
The particular features and objects of the invention as well as other advantages will be appreciated from the following description in connection with the drawings of an embodiment of the invention in which:
When needed, rear yarns may be correspondingly fed through apertures 23 in rear yarn guide plates 24 from another source or supply of yarns. If desired, the needle bar 12 may be slideably mounted and shifted by appropriate pattern control means in a well known manner, such as by cams, roller drives, or hydraulic shifters.
Supported upon a needle plate 32 and fixed to bed frame 33 are a plurality of straight rearward projecting transversely spaced needle plate fingers 34 extending between the vertical needle paths of the reciprocal needles 14. The substrate or base fabric 35 is supported for longitudinal rearward movement over the needle plate 32. The base fabric is drawn by conventional fabric feed mechanism or substrate drive such as a belt and pulley mechanism or servo motors powering spiked substrate drive rolls 27, 28.
The needle drive mechanism, not shown, is designed to actuate push rod 16 to vertically reciprocate the needle bar 12 and to cause the needles 14 to simultaneously penetrate the substrate 35 far enough to carry the yarns 18 through the substrate 35 to form loops therein. After the loops are formed, the needles 14 are vertically withdrawn to their elevated retracted position disclosed in
A looper apparatus 40 made in accordance with the invention includes a plurality of transversely spaced hooks 41, there being at least one hook 41 for each needle 14 in the usual case. The hooks 41 are arranged so that the bill 42 of a hook 41 will cross and engage each needle 14 when the needle 14 is in its lowermost position and in a well known manner seize the yarn 18 and form a loop therein. The bills of the hooks 41 point forward opposite the direction of the fabric feed as indicated by the arrow 30. Hooks 41 are mounted in hook bars and secured at the upper end of rocker arm 47. Any conventional means to oscillate the rocker arm 47 may be provided. In a customary embodiment, the lower end of the rocker arm 47 is clamped to laterally extending rock shaft 49. Pivotably connected to the upper portion of the rocker arm 47 is one end of a connecting link 48 having its other end pivotably connected to a jack shaft rocker arm mounted on a jack shaft which has an oscillating motion imparted thereto by a drive means, such as a cam and lever apparatus in communication with the main drive shaft, so that the jack shaft oscillates in timed relationship to the reciprocation of the needles 14. The tufting machine 10 also incorporates a plurality of knives 36 which may cooperate with the hooks to cut selected loops to form cut pile tufts or bights of yarn as hereinafter described. The knives 36 may be mounted in knife blocks 37 and then mounted to a knife shaft rocker arm 39 which is clamped to knife shaft 38. Oscillatory movement is imparted to the knife shaft 38 to conventionally drive the knives into engagement with one side of the respective hooks 41 as known in the art to provide a scissors-like cutting action.
In conventional tufting machine operation, the yarn feed pattern control mechanism 21 is programmed to feed selected yarns 18 at varying lengths in order to produce a desired high-low pattern of tufted bights of yarn. The yarns 18 can be selected from different colors or varying size or physical characteristics. Additional patterning capability may be provided by shifting the needle bar 12 as the substrate 35 moves in the direction of arrow 30 rearwardly through the machine 10. The patterns formed on the substrate 35 appear on the bottom surface 45 while the upper surface 44 of the substrate 35 contains the back stitching necessary to permit needles 14 to move from one tufting location to another. After passing through the tufting zone, the backing fabric 35 is directed under a presser foot 22 and upward away from the tufting zone to provide space for the gated looper apparatus 40 of the present invention.
Central to the operation of gated loopers is the use of pneumatic cylinders 50 as shown in
Slot 60 is adapted to receive a first end 62 of connector 61. The connectors 61 have first ends 62 interfacing with drive rods 54. The connectors 61 also have a body 64 and a second end 63 that interfaces with rear end 7 of sliders 70. In operation the sliders 70 pass through the hook block so that their front ends 72 are moveable to selectively open or close the lip formed by hook bill 42 of an associated hook 41, all as explained in greater detail in U.S. Pat. No. 7,222,576 which is incorporated herein by reference.
In operation, it is preferred that a constant low pressure be introduced into the cylinder blocks 43 through inlets 46 which tends to move all of the pistons 52 and their associated drive rods 54, slots 60, and tips 59 to a rear position that retracts the corresponding slider 70 and leaves the lip of the associated hook open. It can be seen in
Generally, the high pressure applied to the inlets 51 of pneumatic cylinders 50 will be about sixty pounds per square inch and the lower pneumatic pressure applied through inlets 46 of cylinder blocks 43 will be about thirty pounds per square inch. However, these pressures are not critical and lower pressures of about 40-20 lbs per square inch and higher pressures of about 100-50 lbs per square inch produce suitable results. Higher pressures produce a faster response time for the pistons 52 and their associated looper gates but also impose greater stress on components of the system.
It will be seen that in a double acting cylinder system according to the invention, only the high pressure gas applied to inlets 51 of pneumatic cylinders 50 need be controlled on a cylinder by cylinder basis. The low pressure applied to cylinder blocks 43 remains constant so there is constant force urging the pistons to move their associated sliders back into the rear piston position that leaves the associated hooks uncovered. Thus, it is only necessary to communicate pattern information to controllers that supply high pressure gas to the pneumatic cylinders 50 and the low pressure tending to return the pistons 52 to their retracted position is constant.
Each of the foregoing patents, patent applications and publications mentioned herein is incorporated in its entirety in this disclosure by reference. Although preferred embodiments of the present invention have been disclosed in detail herein, it will be understood that various substitutions and modifications may be made to the disclosed embodiment described herein without departing from the scope and spirit of the present invention as recited in the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 61048743 | Apr 2008 | US |
