US3236264A - Jacquard machines - Google Patents

Description

United States Patent Office 3,236,264 Patented Feb. 22, 1966 3,236,254 JACQUARD MACHENES Lothar Sirach, Wiihelrnsfeld, Heidelberg, Germany (Pfarrgasse 3, Vaduz, Liechtenstein) Filed July 30, 1963, Ser. No. 298,623 3 Claims. (Cl. 13959) The present invention is concerned with the prevention or at least the reduction of slide friction between the warp threads and heald eyes in a loom. With the conventional arrangement of healds in a loom (including both the heald frame arrangement where a large number of heald wires are laid side by side in a frame, and the Jacquard arrangement, where each heald wire is individually loaded, and only a few wires are harnessed together) there is considerable friction between each warp thread and the heald eye each time that warp thread is raised by the pattern mechanism. This is because the length of the thread from the fell of the cloth to the heald eye increases as the heald eye is raised, and this increase causes stretching of the warp thread between the fell of the cloth and the warp beam. This frictions is, of course, undesirable.

A second problem is that the degree of sliding friction varies between threads which pass through heald eyes which are near to the cloth and those which are further away. This difference becomes appreciable where there is a considerable depth of heald eyes from front to rear, as in a Jacquard loom.

As disclosed in German Patent No. 853,427, that in order to obviate sliding fraction, each heald eye should travel on an arc of radius r given by the formula:

where a is the horizontal distance from the fell of the cloth to the heald eye in the closed shed position, and b is the horizontal distance from the heald eye in the closed shed position to the point at which the warp thread leaves the back roller, the centre of the are being in front of the heald eye, so that the curve is upward and forward.

In practice it is very difiicult, if not impossible, to make a heald eye travel on a curved path. The invention is based upon the conception of moving the heald eye along a straight line which is a secant to the theoretical curve given by the formula the secant of the selected path having a maximum depth of half the maximum depth of a secant which joins the position of a point on the heald in the closed shed posi tion with the position of that point at the open shed position if the heald were to move in the theoretical curve.

Thus the heald eyes are made to travel on forwardly and upwardly inclined paths, the slope of which is determined by the formula specified above. It can be shown that this selected path is near enough to the theoretical curved path to reduce the forces trying to produce sliding friction to very small forces. In fact, it is possible to reduce these forces to such a low value that they are less than the frictional forces tending to cause the thread to adhere to the eye, and when this is achieved, no sliding takes place.

The invention is particularly applicable to looms fitted with jacquard mechanism, wherein each Warp thread is individually loaded, because it is a relatively simple matter to cause each heald to be inclined in the selected path.

According to a preferred feature of the invention, each heald is provided with an elastic lingoe, the lower end of which is anchored to the loom frame in such a position that it causes the heald to lie in the selected path.

The invention will be more clearly understood from the following description of the heald arrangement in a loom fitted with a jacquard mechanism, which description is given by way of example of the invention.

In the accompanying drawings:

FIGURE 1 is a diagrammatic end view of a loom showing only the parts which are necessary for an understanding of the invention,

FIGURE 2 is a diagram showing the theoretical con siderations, and

FIGURE 3 is a diagrammatic view of an alternative arrangement.

The general arrangement of the shedding mechanism is shown in FIGURE 1. Part of the loom bottom frame is shown at 10, and 12 is the sley sword pivoted at 14 on the frame in the usual manner. The sley is shown at 16, and 18 represents the shuttle; 20 is the back roller over which the warp threads 22 and 24 pass on their way from the warp beam 26 to the cloth which is shown at 28 passing over the sand roller 30. Only two warp threads are shown in FIGURE 1, but it will be appreciated that under normal weaving conditions there will be many hundreds of warp threads, all following the same kind of path to the cloth.

The jacquard mechanism is indicated in the upper part of FIGURE 1, and again only sufficient mechanism is illustrated to operate two warp threads. 32 and 34 are hooks formed with nebs 36 at their upper ends for engagement by the grifie blades 38 on the griffe frame 40. The conventional lifting mechanism (not shown) is provided for raising and lowering the griffe frame 40 as indicated by the double arrow 42. A set of pattern cards 44 are presented one at a time by a rotatable and reciprocable cylinder 46 to needles 48, one of which is associated with each of the hooks 32 and 34. If a needle 48 is depressed by a pattern card, then it will push its hook to move the neb of that hook out of the path of movement of the grifie blade 38, and consequently that hook will not be raised. If, on the other hand, a needle is not depressed, its hook will be raised by the griife.

All the mechanism so far described is conventional in looms fitted with jacquard machines, and for this reason, the mechanism has not been described in detail.

Each hook 32, 34 has a harness cord 50 attached to its lower end, and this cord passes through a hole 52, 54 in the harness board 56, and the upper end of a flexible heald 58, is attached to each harness cord. (In the diagrammatic arrangement of FIGURE 1, each hook has one harness cord, and one heald. In practice, it will be usual for several harness cords each with its own heald to be attached to each hook, to provide for repeats in the pattern being woven.) These is a heald eye 62, 64 in each heald, and the lower end of each heald is attached to an elastic lingoe 66, 68 made of rubber and anchored at its lower end to the loom frame 10. The elastic lingoes stretch each time their heald is pulled upwardly, but they contract to pull the heald down as soon as the griffe supporting the raised heald begins to lower. It is preferred to use elastic lingoes rather than ordinary weighted lingoes, because they lend themselves to a simple arrangement for sloping the healds as will be further described, and also because they can be designed to extend and contract substantially free from inertia, and this enables the shedding mechanism to operate at greater speeds than would be possible with weighted lingoes.

As is clearly shown in FIGURE 1, the anchor points for the lower ends of the lingoes are to the rear of the corresponding holes in the harness board 56, so that each heald occupies a sloping position being inclined forwardly and upwardly. As the heald is pulled upwardly,

the lingoe will stretch, and the heald eye will follow the same straight line path as that at which the heald lies. The angle of slope of this path is very important in order to minimise or obviate sliding friction between the warp thread and the heald eye, and this angle is determined as described below. Obviously, once the correct angle of slope has been determined, it is a simple matter to ascertain the distance by which each lingoe anchor must be offset to the rear of the corresponding hole in the harness board.

Referring now to FIGURE 2, there is shown a warp thread wu which extends in the invention from a position A (which is the fell of the cloth) up to a position C, (which represents the heald eye in the open shed position) and then down to a position B (which represents the position at which the warp thread comes off the back roller). The closed shed position of the heald eye is indicated at C (where the warp thread lies horizontally) and the horizontal distance between A and C is designated a and that between C and B is designated b. The vertical lift produced by the jacquard mechanism is designated D, and this is determined by the consideration that the warp threads must be lifted high enough to allow the shuttle 18 to pass beneath the raised threads.

Now Professor Michelitsch has shown in said German patent that the theoretically correct path of the heald eye follows a curve designated C in FIGURE 2, having a radius r, where According to this formula, the heald eye would arrive at a position C A secant to the curve C which passes through the points C and C is shown by a chain dotted line S, and the maximum arc height of this secant is shown as h max. According to the present invention, the heald eye is made to travel to point C along a secant S which has a maximum arc height of h max./ 2. It is obvious that this secant is very close to the theoretical curve C, so that the forces tending to slide the warp thread through the heald eye are only very slightly greater than the zero force obtained by the theoretical curve. Moreover, it is a relatively simple matter to arrange for the heald eye to travel along this secant, by sloping the healds as has been described.

Exactly how small the slide inducing force is can be appreciated from the following example.

Supposing the power required to lift a heald is 0.01 kg., and the adhesive power coefiicient between the warp thread and the heald eye is 0.2 to 0.7. Then powter required to break the adhesion due to friction between the thread and the eye is 1 0.01 0.2=0.002 kg. (minimum) a b ba R=860 mm.

The are height h (max) is 1.4 mm.,

And

max.

With these conditions, it can be shown that the force tending to move the thread through the eye is 0.14 (power required to lift heald), which in this example is (2) 0.14 0.0l=0.0014 kg.

Since the force tending to move the thread through the 4 eye (0.0014 kg.) is less than that required to break the adhesion (0.002 kg.), it will be apparent that no movement will take place, and consequently there is no friction. If we now consider a second warp thread passed through an eye which is nearer to the rear of the loom, we have the following arrangement:

Foreshed (a) :750 mm. Rear shed (b) :950 mm. Shed height=150 mm. R=3550 mm.

Therefore, h max. is much less than for the radius R 860 mm. in the case of the previously taken warp thread, and consequently there is even less force tending to move the thread through the eye in this case. It will be appreciated that there would be movement of the thread through the eye, in any case where the force tending to create such movement exceeded the adhesive force between the thread and the eye. It is clear from the above example that this would only occur if the fore shed length a were small relatively to the rear shed length b so giving relatively small value to the radius R. In practice, such a relationship is unlikely to occur.

The elastic heald portion 66, 68 provides two advantages, in that it permits the heald 58 to be inclined as described above, and as previously mentioned it can be designed so as to extend and contract substantially free from inertia, and therefore enables the mechanism to be operated at a much greater speed than is the case when weights or lingoes are employed. The high operational speed coupled with the minimising of friction at the heald eye, and the means for adjusting the height and duration of the shed, combine to substantially reduce the risk of warp breakage.

In the alternative arrangement shown in FIGURE 3, each heald 70 at attached to the harness cord 72 at its upper end, and there is a harness board 74 similar to the harness board 56 shown in FIGURE 1. In this instance, each heald has a conventional weight lingoe 76, and the inclination of the healds to the required angle is achieved by rods 78 fixed to the loom frame, over which the lingoe cords 80 are made to pass. The position of each rod 78 determines the angle of slope of all of the healds associated with it.

The invention has been described as applied to a jacquard mechanism in which the shed is formed entirely above the plane of the warp threads when the shed is closed, but it will be appreciated that it can equally well be applied to mechanism in which the shed is formed by lifting some of the warp threads and lowering the remainder of the warp threads. The lifting of warp threads will thus be against the section of the elastic healds, and the lowering of the other warp threads will be effected by the elastic healds under the control of the descending griffes.

I claim:

1. In a loom, healds having eyes through which pass warp threads for raising and lowering said warp threads to produce a pattern, mechanism operatively connected to said healds to cause lifting and lowering motion of said healds, and constraining means operatively connected to said healds to incline said healds at a predetermined angle to the direction of said lifting and lowering motion to cause said heald eyes to follow a straight line path inclined to the vertical during rising and falling motion of said healds, said path being a secant to the theoretical curve given by the formula curve, a is the horizontal distance from the fell of the cloth to the heald eye in the closed shed position, and b is the horizontal distance from he heald eye in the closed shed position to the point at which the warp thread leaves the back roller.

2. In a loom, a set of individual healds each having its own heald eye and disposed at a predetermined angle to the vertical, pattern and lifting mechanism connected to all of said healds to cause raising and lowering of said healds to produce a pattern in the cloth, a set of elastic lingoes one connected between the lower end of each of said healds and one of a corresponding set of anchorage points on the loom frame below the lifting mechanism, said anchorage points being so disposed relatively to said lifting mechanism as to cause each of said healds to lie in a straight line at said angle, said straight line being a secant to the theoretical curve given by the formula the secant of the said straight line having a maximum depth of half the maximum depth of a secant which joins the position of the heald eye in the closed shed position with the position of the heald eye at the open shed position if the heald eye were to move in the said theoretical curve, where r is the radius of said theoretical curve, a is the horizontal distance from the tell of the cloth to the heald eye in the closed shed position, and b is the horizontal distance from the heald eye in the closed shed position to the point at which the warp thread leaves the back roller.

3. In a loom, a set of individual healds, each with its own heald eye and disposed at a predetermined angle to the vertical, a jacquard mechanism having a series of hooks, harness cords connecting said healds to said hooks, a set of elastic lingoes one connected between the lower end of each of said healds and one of a corresponding set of anchorage points on the loom frame below the lifting mechanism, said anchorage points being so disposed relatively to said lifting mechanism as to cause each of said healds to lie in a straight line at said angle, said straight line being a secant to the theoretical curve given by the formula the secant of the said straight line having a maximum depth of half the maximum depth of a secant which joins the position of the heald eye, the heald eye in the closed shed position with the position of the heald eye at the open shed position if the heald eye were to move in the said theoretical curve, where r is the radius of said theoretical curve, a is the horizontal distance from the fell of the cloth to the heald eye in the closed shed position, and b is the horizontal distance from the heald eye in the closed shed position to the point at which the warp thread leaves the back roller.

References Cited by the Examiner UNITED STATES PATENTS 2,737,981 3/ 1956 Pfarrwaller 139-1 FOREIGN PATENTS 658,116 l/ 1929 France. 1,186,385 2/1959 France. 1,224,523 2/ 1960 France.

853,427 10/ 1952 Germany. 887,777 8/1953 Germany.

15,680 1906 Great Britain. 257,737 9/ 1926 Great Britain.

DONALD W. PARKER, Primary Examiner.

Claims (1)

1. IN A LOOM, HEALDS HAVING EYES THROUGH WHICH PASS WARP THREADS FOR RAISING AND LOWERING SAID WARP THREADS TO PRODUCE A PATTERN, MECHANISM OPERATIVELY CONNECTED TO SAID HEALDS TO CAUSE LIFTING AND LOWERING MOTION OF SAID HEALDS AND CONSTRAINING MEANS OPERATIVELY CONNECTED TO SAID HEALDS TO INCLINE SAID HEALDS AT A PREDETERMINED ANGLE TO THE DIRECTION OF SAID LIFTING AND LOWERING MOTION TO CAUSE SAID HEALD EYES TO FOLLOW A STRAIGHT LINE PATH INCLINED TO THE VERTICAL DURING RISING AND FALLING MOTION OF SAID HEALDS, SAID PATH BEING A SECANT TO BE THEORETICAL CURVE GIVEN BY THE FORMULA

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