US2071414A - Knife cutting mechanism for looms - Google Patents

Description

Feb. 23, 1937; J. LOWRIE KNIFE CUTTING MECHANISM FOR LOOMS Filed April 22, 1936 l 73 MW GN m/ m E T WM M @a Patented Feb. 23, 1937 UNITED STATES PATENT OFFIQE 3 Claims.

This invention relates to an improved combination of circular knives for use in cutting the loops in the operation of weaving pile fabrics, particularly carpets. It may also be used in other machinery where similar cutting work needs to be done. The particular object is to mount the circular knives on their shaft, so that any one of them may be replaced quickly and conveniently as compared to prior practice.

The accompanying drawing and following description will disclose the details of the invention.

Fig. 1 is a side elevation of a rotary cutter mounted on its shaft, showing the position of the pile wire associated therewith;

Fig. 2 is an enlarged view of one cutter mounted on the shaft with the relative position of additional cutters indicated by the dotted lines Fig. 3 is a view taken substantially on line 3-3 of Fig. 2;

Fig. 4 is a view taken on line 4-4 of Fig. 3; Fig. 5 is a detail view of one knife half; and Fig. 6 is a fragmentary view of a modified knife a mounting.

Before considering the improvement, it should be understood what the prior practice is, in mechanism for cutting loops in weaving pile fabrics. It is the principal object of the present invention to improve this particular practice. Such prior practice involves a rotatable shaft, on which a series of circular knives are keyed for rapid rotation. There is one knife for each row of pile loops. The fabric, as it is drawn over the breast beam of the loom, draws the loops formed on each pile wire against the rotary knife for that wire. An example of the prior art mechanism is shown in the Hartley Patent 768,225, August 23, 1904. It is now common practice, as indicated in that patent, to mount each knife so as to rotate in a slot of the pile wire. The walls of this slot spread the loop and tighten it for cutting. The tightening of the loops and their cutting by a rapidly revolving circular knife give very good results in the character of tufts desired. While other mechanisms are in use which do not involve the rotary knives, the latter give such good character to the tufted fabric, that loom designers desire them in the better type of loom constructions in spite of difficulties.

One difficulty is that if a rotary knife breaks or for any reason needs to be replaced, the repair operation not only shuts down the loom but also uses up a lot of time. There are other difficulties that arise in repair work when the rota y knife mechanism is used in a pile fabric loom with certain improvements in it such as shown and claimed in my copending application Serial No. 19,967, filed May 6, 1935.

The mechanism shown in the accompanying 5 drawing is primarily designed as an improved mechanism to make the repair and. replacement of rotary knives in the loom comparatively fast and easy, with the result that the expensive loom can be kept in more nearly constant operation 10 with less lost time.

This is accomplished in the best manner now known to me by making a circular knife of very thin steel (like safety razor blade steel) in two parts, 2 and 2, and removably fastening them on a holding member 3. The adjacent parts of the knife at their ends are held against the member 3 by U-shaped spring clips t, very easily put on and taken off. There is a slot 5 midway between the ends of each knife half and a corresponding notch 5 in member 3. A spring clip has a very short flange 8, just long enough to pass through slot 5 and engage in notch 6. Otherwise, the spring clip l is like the spring clip 4, being generally U-shaped to straddle the holding member 3 and the knife. With this arrangement it will be seen that each knife may be mounted upon and taken off its adjacent holding member by prying, as with a thin blade on the long leg of clip l to disengage its flange 8 from holding relation to the member 3. Then the knife half corresponding to that clip 1 may be lifted off the shaft for repair or replacement. The other knife half may be treated the same way. The member it stays on the shaft.

It will now be clear from the unit assembly above described that the knife holding members 3 may be made to slide on the shaft, each having a flat side 9 in engagement with a corresponding fiat side of the clips 4 and 1, see Fig. 4, to prevent relative rotation. Each member 3 may carry the twohalves of one rotary knife by means of the spring clips. The base of these spring clips may be notched into the adjacent member 3. In a loom three yards wide, by way of example, there may be nine knife assemblies to the inch, the knife holding members may be one-sixteenth of an inch thick and each knife only a few thousandths of an inch thick. Thus, there will be about a thousand knives on the rotatable shaft. For convenience the drawing is on a somewhat enlarged scale for the detail. The common relation of each knife in the loom cutting operation is indicated in Fig. 1. This figure is nearly to an operating scale. The circular knives rotate each between the walls in the slot of each pile wire whose loops the knife serves in cutting. Thus, the pile wires space the knives on the operating shaft and they are not pushed together in abutting relation in their final assembly in the loom, as might appear from the large number on the shaft.

Now, if there is knife trouble in the loom operation, this is the way it is cured. The knife causing the trouble is readily located by the line of the imperfect loop cutting in the product. The loom is stopped and a hand knife is used to out the loops in the rear of the knife giving trouble. These loops are out along the top of the corresponding pile wire and also on the adjacent pile wires at each side. This hand cutting of the loops releases the aligning tension of the loops in the product on the pile wires whose slots hold the knives spaced on the shaft. Thus, adjacent the defective knife, the knives on each side may be pried away enough at the sides to manipulate the spring clips to remove and replace the defective knife, or only the half injured. As already described, the knife part is taken off its corresponding holding member, and a new one put on very easily and quickly. The member 3 stays on the shaft and is necessarily held close to its operating position. As soon as the repair is made the loom is started up again. And the pile loops traveling forward on the pile wires with the product will realign the knife assemblies which were only slightly disturbed from their true alignment in making the repair. The result is that rotary knives can now be used in this character of pile fabric looms and their use will not cause difficulties found in the prior art.

My improvement has a special advantage in combination with the loom mechanism shown in my aforesaid copending application. In that mechanism the ordinary rotary knife mechanism would have even more than the usual difliculties in repair work. But the invention as herein disclosed is useful for the advantages it will give in repair work of pile fabric looms of many different specific constructions.

The principles of the invention will now be clear from the above specific description of how to practice it in the preferred manner. In Fig.

6 I have indicated a modified form for a spring clip to hold the knife halves on the holding memher. In this form the depressions [5, one of which is shown in the fragmentary view of Fig. 6, in one leg of the clip pass through holes near the ends of adjacent knife halves and press resiliently into recesses H5 in the holding member 3. Otherwise, the construction is the same. The modification merely illustrates the point that the following claims may have a broader interpretation in some respects than might appear from the preferred form of disclosure alone.

I claim:

1. In mechanism for the purpose described a knife holding member, a flat annular knife blade made in half portions, spring clips fashioned to removably hold said half portions on said knife holding member, a rotatable shaft on which the knife holding member is mounted, one of said spring clips having such engagement with the shaft as to key the knife assembly for rotation with the shaft.

2. In mechanism for cutting loops in a pile fabric loom the combination of a flat annular disk, a very thin annular knife blade of larger external diameter and substantially the same internal diameter as said disk, said knife blade being made in two diametrically divided halves, each half being removably held on the disk by a spring clip of U-shaped form with the base of such form engaging the internal edge of the disk and blade and with one of the legs of the clip having a short end flange suflicient to snap into a slot in the side face of the knife blade and overlie the edge of the disk.

8. In mechanism for cutting loops in a pile fabric loom the combination of a flat annul r disk, 2. very thin annular knife blade of larger external diameter and substantially the same internal diameter as said disk, said knife blade being made in two diametrically divided halves, each half being removably held on the disk by a spring clip of U-shaped form with the base of such form engaging the internal edge of the disk and blade, the spring clip construction for the purpose stated having dimples passing through holes in and aligning each knife half.

JOHN LOWRIE.

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