EP0191955B1

EP0191955B1 - Batten for weaving loom

Info

Publication number: EP0191955B1
Application number: EP19850201218
Authority: EP
Inventors: Bernard J. Pauwels; Paul J. Huyghe; Ignace P. Meyns
Original assignee: Picanol NV
Current assignee: Picanol NV
Priority date: 1985-02-19
Filing date: 1985-07-22
Publication date: 1989-05-03
Also published as: DE3569945D1; EP0191955A1; BE901765R

Description

The invention involves a weaving loom having a batten.
More especially, the invention relates to a weaving loom the batten beam of which is con- stucted as a counter weight.
In particular, the invention involves a weaving loom having a batten in which the gravitational axis of the batten, including any counter weight, does not coincide with the oscillatory axis, but lies instead at a certain distance under the oscillatory axis.
In a preferred appliation, the batten is constructed such that together with the aforementioned characteristics, it also exhibits a minimum mass moment of inertia in relation to its centre of gravity or gravitational axis.
Known weaving looms are mainly equipped with a batten consisting of a cylindrical batten shaft mounted in a bearing upon which batten legs, reed beam and reed mounted. As a result of this, the gravitational axis does not coincide with the oscillatory axis, and the gravitational axis always lies on the side of the reed with respect to the oscillatory axis, which amounts to the gravitational axis lying above the oscillatory axis.
Thus it has often been proposed that the batten should be equipped with counterweights in such a way as to be in accordance with the general principle of equilibrium, which is known from the science of dynamics, according to which the counter weights are fitted to an oscillating body such that the centre of gravity of the overall structure lies at the oscillatory axis thereof.
A well-known application provides a solution in which the original batten shaft is displaced over a fairly large distance with respect to the oscillatory axis by the use of crank webs. Such a construction offers the advantage that the total weight of the batten remains practically unchanged, whereby the displaced batten shaft operates as a counter weight and the batten legs are usually produced hollow so that the total weight of a batten balanced in this way is not greater than that of the ubalanced batten. Such an application is known, for example, from USA patent No. 4.076.048.
Despite having the favourable characteristic of not or hardly increasing the total weight of the batten, such a known construction has the disadvantage that the interia or the mass moment of inertia around the oscillatory axis increases greatly. Indeed, it is known that when the oscillatory axis of an object oscillating around its gravitational axis is displaced, its inertia increases both in direction proportion to its mass and proportionally to the square of its displacement. Displacing the batten shaft in such a known way causes a consequent substantial and undesirable increase in the mass moment of inertia of the batten, even if the mass is not increased. The aforementioned know solution thus has the disadvantage that the drive torque of the batten is considerably increased.
Of the document BE 899.057, a batten beam mounted in bearings is known with three parallel axes, the axis of oscillation 0-0 and the gravitational axis Z-Z of which lie inside the batten beam, and the latter axis lies between the axis of oscillation 0-0 and the geometrical axis A-A. The aim of this Belgium patent was a batten offering the advantage of creating minimum forces directed to the floor. The present invention provides in a further amelioration by providing in a weaving loom having a batten in which a compromise is sought between the vertical and the horizontal forces, in order to become both as low as possible, in combination with a minimum mass of inertia.
To this end, the invention relates to a weaving loom having a batten of the type consisting of a full batten beam mounted in a bearing, upon which batten components such as batten legs, reed beam and reed are mounted, whereby the batten is mounted in the bearing such that its oscillatory axis runs parallel to the geometrical axis of the batten beam and the gravitational axis of the whole formed by the batten beam and the said components mounted thereon, whereby the oscillatory axis lies outside and the gravitational axis does not lie outside the periphery of the batten beam, and in that the gravitational axis lies between the oscillatory axis and the geometrical axis.
In a variation of the invention, there is a batten fitted in which the distance between the oscillatory axis and the gravitational axis is chosen such that there is a compromise between the values of firstly the horizontal and secondly the vertical components of the forces in the supporting points. This offers the advantage that firstly the horizontal components of the forces are smaller than those in an unbalanced batten and secondly that the vertical forces are smaller than those in the completely balanced case. It is obvious that the forces under consideration here are at all times the forces which are attributable to the movement of the batten.
With a view to better demonstrating the characteristics according to the invention, a number of representative but not exhaustive examples of some preferred applications are discussed below with reference to the accompanying sketches, in which:

figure 1 shows a front view of a batten according to a practical application of the invention;
figure 2 shows a section through line II-II in figure 1;
figure 3 shows the distribution of the most important forces in a weaving loom in which the centre of gravity of the batten shaft lies under the oscillatory axis.

In figures 1 and 2 can be seen the batten, which chiefly consists of a fully cylindrical batten beam and a number of batten legs 2 attached onto it which carry a reed support 3, onto which the reed 4 is attached.
Lines A-A, 0-0 and Z-Z show the geometrical axis of the batten beam 1 and the oscillatory and gravitational axis of the batten respectively, all three axes running parallel to each other. The gravitational axis Z-Z lies underneath the oscillatory axis 0-0, whereby axis Z-Z lies not outside the circumference of the batten beam and axis 0-0 lies in accordance with the invention, outside the circumference of the batten beam (1). The beneficial effect created by this is explained below using figure 3. The following will also show the importance of the distance r between the oscillatory axis 0-0 and the gravitational axis Z-Z.
Figure 3 shows a schematic representation of a weaving loom 5 which is fixed onto supporting points 6 and 7. For the sake of simplicity, as indicated in the figure and also the following dissertation, the starting point will be taken as the most representative and simplified model, in which the batten is represented by a point mass m situated at the aforementioned distance r from the oscillatory axis 0-0 and an inertia around the centre of gravity. For the same reason, the point mass m is shown in its lowest position so that the instantaneous acceleration due to the rotational acceleration, equal to r.a, acts horozin- tally.
It is clear that when the point mass m is at its lowest position, the oscillatory axis O-O, the gravitational axis Z-Z and the geometrical axis A-A are loated in a vertical plane in which the moment due to the rotational acceleration, La, is reacted against by the moment of the force due to the horizontal component of the translational acceleration m.r.a.Z in such a way that they both cancel each other out.
The most important dynamic forces which arise with such a batten moving backwards and forwards and which have to be absorbed in the supporting points 6 and 7 are:

^* the horizontal component of the force due to the translational acceleration m.r.a;
^* the moment which arises due to the rotational acceleration La, in which I represents the mass moment of inertia of the batten with respect to the gravitational axis Z-Z.

These values are obtained from the general theory of mechanics, from which it is known that the forces on a moving body may be considered as being equivalent to the combination of firstly a force which acts through the centre of gravity of the body and secondly a moment with respect to the centre of gravity.
Given the aforementioned moment together with the aforementioned force, the forces directed toward the supporting points may be simply calculated by a known process. The values are thus merely given without further ado in figure 3, and consist chiefly of a horizontal force component:
and directly opposing vertical force component Fv at each supporting point 6 and 7,
Here the values L and Z represent the distance between the two supporting points 6 and 7 and the height of the mass m above them respectively.
From the aforegoing, it may be seen that the forces Fv are composed of two opposite force components, the first of which arises due to the aforementioned moment I.a and the second of which arises due to the moment of the force through m with respect to the supporting points 6 and 7.
According to a known possibility, the distance r between the oscillatory axis 0-0 and the gravitational axis Z-Z can be selected such that the absolute values of both components of each of the forces Fv, namely La/L and m.r.a.Z/L, are equal.
As both components are vectorially opposed, consequently each force Fv in each of the supporting points 6 and 7 is equal to zero, since r = I/m.Z.
However, according to the present invention the distance r is selected such that, depending upon the desired result, a compromise is created between the values of the vertical force components Fv and the horizontal force components Fh, this in combination with the advantageous feature that 0-0 lies outside the circumference of the batten beam and that the gravitational axis lies inside or on the circumference of the cylindrical batten beam 1.
It is obvious that, according to the desired result, a craftsman can determine the distance r by a calculation using the aforegoing line of reasoning or by conducting comparative tests with a number of battens.
In order to limit the horizontal force component Fh, in addition to the aforementioned properties the aim is to manufacture the batten concerned in such a way as to minimize the mass moment of inertia I of the gravitational axis Z-Z.
The advantage of this is as follows. When designing a batten for a particular weaving loom, the starting point used is a number of previously known parameters, some of which are constant and others of which can be considered as constant. In the same way, if the starting point used is the aforementioned model from figure 3, then the values of the distance L and the angular acceleration can be assumed to be constant parameters. The value of Z shows little variation in the various designs, and can be considered to be approximately constant.
In the preferred application according to the model of figure 3, the absolute values of the components I.a/L and m.r.a.Z/L are necessarily equal. From this it can be deduced that the product m.r.a, i.e. the magnitude of the horizontal force component Fh, is determined by the quotient of I/Z, or that in the event of the value of Z being considered to be constant, the force Fh is proportional to the moment of inertia I.
From the aforegoing, it may be seen straight away that in this application of the batten, the aim will be to achieve a minimum mass moment of inertia I in order to hold the horizontal force component Fh to a minimum.
For this reason in the embodiment form shown in figures 1 and 2, the batten is so constructed as to minimize the mass moment of inertia I of the overall batten with respect to the gravitational axis Z-Z. To this end, the exterior surface of the fully cylindrical batten beam 1 is adjacent to the gravitational axis Z-Z. The aforementioned characteristic, whereby the gravitational axis Z-Z lies between the oscillatory axis 0-0 of the batten and the geometrical axis A-A of the batten beam 1 is of course maintained.
This last application is constructed with a mass of 112 kg, with the gravitational axis Z-Z lying at a distance (2) of 0.079 metres from the oscillatory axis 0-0. The values of L and Z are 1 metre and 0.844 metres respectively. The order of magnitude of the angular acceleration a is 1800 rads/ _S ² with a loom speed of 475 revolutions per minute. The moment of inertia of the practical application is 0.75 kg m². The forces I.a/L and m.r.aZ/L cancel each other out here, and each have a value of practically 1350 Newtons at the speed under consideration.
The invention is in no way restricted to the applications described and shown in the accompanying sketches as examples, and such a batten may be manufactured in all types of shapes and sizes without extending beyond the scope of the invention.

Claims

1. Weaving loom having a batten of the type consisting of a full batten beam (1) mounted in a bearing, upon which batten components such as batten legs, reed beam and reed are mounted whereby the batten is mounted in the bearing such that its oscillatory axis (0-0) runs parallel to the geometrical axis (A-A) of the batten beam (1) and the gravitational axis (Z-Z) of the whole formed by the batten beam (1) and the said components (2, 3 and 4) mounted thereon, whereby the oscillatory axis (0-0) lies outside and the gravitational axis (Z-Z) does not lie outside the periphery of the batten beam (1), and in that the gravitational axis (Z-Z) lies between the oscillatory axis (0-0) and the geometrical axis (A-A).

2. A weaving loom according to claim 1, characterised in that the batten beam (1) has a circular section and that the gravitational axis (Z-Z) lies on the circumference of the batten beam (1).