Abstract:
A cam motion machine that includes several cams each defining at least one running track for a follower roller. Each cam is provided with a centering bore that permits mounting of the cam on a drive shaft, while elements are provided to apply a tightening force parallel to the drive shaft with a non-circular section. At least one washer-spacer, for which an internal edge is non-circular and designed to enable an axial displacement of the washer-spacer along the shaft, is fixed to rotate with the shaft and is in contact with at least one of the cams. The washer-spacer may be fixed to the cam by adherence and to the shaft by cooperation of shapes due to complementary projections provided on one of the shaft and the washer-spacer. 
     It would be appreciate if the Examiner would indicate the acceptance of this amendment to the Abstract in the next office communication.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a cam motion machine. The invention also relates to a washer-spacer and a cam for such a machine, a weaving loom in which such a machine is installed, and a method of assembly of such a machine. 
   2. Brief Description of the Related Art 
   In the field of looms, cam motion machines are known that comprise a series of oscillating levers, with one lever for each heddle frame to be installed on the loom. Each oscillating lever is designed so that it can be coupled to one of the frames and equipped with two rollers that cooperate with the two tracks of a complementary cam driven in rotation by a shaft common to the machine. The cams must be installed on a drive shaft to which they are fixed in rotation by adherence under the effect of an axial force applied by appropriate tightening means, after these cams have been adjusted to be at specific angles with respect to each other as a function of the required machine. 
   Such a connection by adherence is sometimes insufficient to firmly fix the cams with respect to their drive shaft. Considering the performances required for modem cam motion machines, their rotation speeds are increasingly high to the extent that torques applied by follower rollers on the cams can offset the angle of the cams on this shaft, which causes maladjustment of the machine and lowers the manufacturing quality of the fabrics. 
   SUMMARY OF THE INVENTION 
   This invention is intended in particular to overcome these disadvantages by proposing a cam motion machine for which the cams can be fixed securely on their drive shaft. 
   With this in mind, the invention relates to a cam motion machine for a loom that comprises several cams each defining at least one running track for a follower roller, each cam being provided with a centring reaming on a drive shaft, while means are provided to apply a tightening force parallel to the drive shaft. This machine is characterised in that:
         the section of the shaft is non-circular,   at least one washer-spacer, for which the internal edge is non-circular and designed to enable an axial displacement along the shaft and to fix the washer-spacer and the shaft in rotation, is arranged around the shaft bearing in contact with at least one of the cams.       

   In such a machine, the washer-spacer may be fixed in rotation by adherence with respect to the cam due to the axial tightening force, while cooperation of the internal edge of the washer-spacer and the non-circular peripheral surface of the drive shaft efficiently fixes the washer to the shaft in rotation by cooperation of shapes. 
   According to advantageous but non-compulsory aspects of the invention, such a machine may incorporate one or several of the following characteristics, taken in any technically acceptable combination:
         The washer-spacer is compressed between two cams under the effect of the tightening force.   One of the cams on which the washer-spacer bears is provided with a recess in which this washer-spacer fits, on at least one of its side faces perpendicular to its running track(s). In this case, each cam may be provided with a recess, while a washer-spacer engaged around the shaft is placed in each recess. An assembly formed from a washer-spacer and the cam in the recess in which this washer is located may be 12 mm thick. Furthermore, the face of the washer-spacer in position in the recess preferably extends to a distance of 6 mm from a median plane of the cam.       

   Each washer-spacer is provided with a center bore or reaming that is at least partly circular, while a section of the drive shaft is inscribed within a circular envelope with a radius slightly less than a radius of the central bore or reaming of the cams, which enables an adjustment of the angular position of the cams with respect to the shaft. In this case, the drive shaft is provided with at least one area recessed with respect to this circular envelope, while the internal edge of the washer-spacer is provided with at least one projection that can engage in this recessed area. At least one edge of this projection may be approximately complementary to a bottom edge of this recessed area. 
   The invention also relates to a loom fitted with a cam motion machine like that described above. Such a loom is more reliable, to the extent that the angular position of its cams is fixed, even when the loom is working at high speed. 
   In the context of the same global inventive concept, the invention also relates to a washer-spacer of a cam motion machine for a loom, this washer being flat with a constant thickness and provided with a non-circular internal edge designed to enable axial displacement along a drive shaft of the cams of the machine, and to fix the washer-spacer in rotation with this shaft, this washer also being designed to be pushed into contact with at least one cam of the machine under the effect of a tightening force parallel to this shaft. 
   Still considering the overall inventive concept, the invention also relates to a cam for a cam motion machine for a loom, this cam defining at least one running track for a follower roller while being provided with a central bore or reaming which permits mounting of the cam on a drive shaft. This cam is provided with a recess that runs along an edge of its central bore and opens up into this bore, on at least one of its side faces perpendicular to the running track, this recess being designed to hold a washer-spacer like that mentioned above arranged around the drive shaft when the cam is mounted on this shaft. 
   This cam may be mounted around a drive shaft for a motion machine, while holding a washer in its recess used to effectively fix the cam and the washer in rotation by bonding and by cooperation of shapes between the washer and the drive shaft. 
   Advantageously, the cam is provided with a groove on at least one of its side faces perpendicular to the running track, extending globally along a diametric direction of its central reaming. 
   Finally, the invention relates to a method of assembly of a cam motion machine like that described above in which each cam is slid along the drive shaft until it reaches approximately its planned position along this shaft. This method includes steps consisting of:
         a) placing at least one washer-spacer around the shaft close to at least one of the cams;   b) orienting each cam with respect to the drive shaft, and   c) fixing the cams in position with respect to the drive shaft and with respect to the others, by applying a tightening force of the cams and the washer-spacer(s) parallel to the shaft.       

   According to one advantageous aspect of this method, an additional step can be provided consisting of:
         d) engaging a gauge in a groove formed on one of the side faces of at least one cam, projecting radially outwards from its running track(s), while   e) during step b), each cam equipped with a groove is oriented by bringing the gauge engaged in this groove to bear in contact with a fixed stop.       

   This method facilitates the angular adjustment of the cams for which the position can easily be found by the operator who knows that he must bring the gauge into contact with the corresponding fixed stop. The order of steps a) and d) could be reversed. 
   Advantageously, when a washer-spacer is arranged between two cams, the gauge engaged in the groove in one of these cams is at a distance from the face opposite the other gauge, while when there is no washer-spacer, the gauge bears in contact with the opposite face under the effect of the tightening force. The thickness of the part of the gauge that projects axially from the groove in which it is engaged is less than the thickness of the part of the washer-spacer that projects axially from the corresponding recess or the total thickness of the washer when there is no recess. Thus, when the washer is in position, the gauge may be withdrawn at the end of the adjustment of the angular position of the cam. On the other hand, if the washer-spacer was forgotten during assembly, the gauge is clamped between two adjacent cams, which prevents or makes it very difficult to withdraw it. The operator can then immediately realise his omission. 

   
     BRIEF DESCRIPTION OF THE DPAWINGS 
     The invention will be better understood and other advantages will become clearer after reading the following description of two embodiments of a cam motion machine, washers-spacers, cams, a loom and methods conforming with its principle, given solely as examples and with reference to the appended figures, wherein: 
       FIG. 1  is a diagrammatic partial view illustrating the principle of a loom conform with the invention, part of the machine being torn off to make the drawing more easily understandable; 
       FIG. 2  is a partial section along line II-II in  FIG. 1  illustrating the principle of a loom; 
       FIG. 3  is a larger scale view of detail III in  FIG. 2 ; 
       FIG. 4  is a section along line IV-IV in  FIG. 2 ; 
       FIG. 5  shows a larger scale front view of a washer-spacer of the machine according to the invention; 
       FIG. 6  is a front view of a cam according to the invention used in the machine according to the invention; 
       FIG. 7  is a cross-sectional view at the same scale as  FIG. 5 , showing the shaft  22  at the line IV-IV in  FIG. 2 , illustrating the principle of a loom; 
       FIG. 8  shows a perspective view of the machine in the previous figures during assembly; 
       FIG. 9  is a larger scale partial sectional view along line IX-IX in  FIG. 8 , and 
       FIG. 10  is a view similar to  FIG. 3  for a machine according to a second embodiment of the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The loom M shown in  FIG. 1  comprises several heddle frames, only one of which is shown in this Figure as reference  1 . The different frames of the loom M are driven by a vertical oscillation movement represented by the double arrow F 1  and controlled by a cam motion machine or mechanism  10  for which the output levers  11  come into contact with the connecting rods  12  associated with the cranked levers  13  connected to each other and to the frame through connecting rods  14 . 
   The number of levers  11  provided is the same as the number of heddle frames  1  and they are installed free to pivot as shown by the double arrow F 2  about the longitudinal axis X 15  of a common shaft  15  supported by the frame  16  of the machine  10 . The machine  10  also comprises several complementary cams  20  each defining two tracks  20 A,  20 B on which rollers  21 A,  21 B bear supported in pairs by levers  11 . 
   The cams  20  are mounted on a common shaft  22  that is supported by the frame  16  and for which a first end  22 A supports a bevel gearwheel  23  designed to cooperate with a bevel gearwheel  24  forming a reduction gear driving the shaft  22  about its longitudinal axis X 22 . 
   Two bearings  25 A and  25 B enable the frame  16  to support the shaft  22  between its end  22 A and cams  20  respectively, and close to the end  22 B opposite shaft  22 . 
   The cams  20  are slid around the shaft  22 , and to achieve this they are each provided with a central bore or reaming  20 C with a circular section centered on an axis X 20  that will be coincident with the axis X 22  when a cam is installed on the shaft  22 . 
   The reaming  20 C can only be partially circular, in other words they can have an edge formed from several non-adjacent circular arcs. 
   As is particularly clear in  FIG. 7 , the shaft  22  has a circular section centered on its axis X 22  and provided with two longitudinal grooves  22 C and  22 D that extend over the length of its part  22 E in which the cams  20  will be fitted. The surface of the cylindrical envelope with a circular base of the part  22 E is denoted C 22  and the radius of this surface is denoted R 22 . The radius of the reaming  20 C 22  is denoted R 22 . The value of the radius R 20  is slightly greater than the radius R 22 , which enables each cam  20  to slide on the part  22 E of the shaft  22 . 
   When the reaming  20 C is partly circular, the radius of its parts along the arc of a circle is chosen as shown above for the radius R 20 . 
   Each cam  20  is provided with a recess  20 D formed on a side face  20 E of the cam  20 , in other words a face perpendicular to the tracks  20 A and  20 B. This recess is also circular and is centered on the axis X 20 . Its outside radius is denoted R′ 20 . The recess  20 D of each cam  20  opens up into the reaming  20 C of this cam. 
   The recess  20 D is provided with a clearance  20 G formed as a groove adjacent to the edge  20 F, close to its external peripheral edge  20 F. 
   A washer-spacer  26  is located in each recess  20 D, and is particularly visible in  FIG. 5 , its external edge  26 A being circular with a radius R 26  less than the radius R′ 20 . The internal edge  26 B of the washer  26  has two circular portions with a radius R′ 26  slightly larger than the radius R 22 , and two teeth  26 C and  26 D with dimensions adapted so that they enter into grooves  22 C and  22 D respectively as shown in  FIG. 4 . 
   The side faces  26 F of the teeth  26 C and  26 D are approximately complementary to the edges  22 F of the grooves  22 C and  22 D, while the teeth  26 C and  26 D can slide along grooves  22 C and  22 D parallel to the axis X 22 . 
   Thus, a washer  26  can be put into place in the recess  20 D of a cam  20 , while its teeth  26 C and  26 D are engaged in grooves  22 C and  22 D. As long as the cams are not in contact with each other, the washer  26  is free to slide in the recess  20 D, while being fixed in rotation on the shaft  22  so that the angular position of the cam can be adjusted. 
   A torque can be transmitted from the shaft  22  to each washer  26  by cooperation between the edges  26 F and the sides  22 F. 
   As is particularly clear in  FIG. 5 , each washer-spacer  26  is flat and has a constant thickness. 
   The thickness e 26  of a washer  26  is greater than the depth P 20  of the recess  20 D on which it is placed, such that when a washer  26  is located in a corresponding recess  20 D, it projects from the face  20 E of the cam  20  in which this recess is formed, over a non-zero width  1  that is relatively small relative to the width of the cam  20 . 
   Thus, the addition of a washer-spacer  26  in a recess  20 D does not significantly increase the thickness of the assembly formed by the washer  26  and the associated cam  20 , denoted e 20  in  FIG. 3 , compared with the thickness of the cam alone. In practice, the thickness of the assembly  20 + 26  is 12 mm. A median plane of the tracks  20 A and  20 B of a cam  20 , in other words a plane at equal distance from these tracks, is denoted P. The side face of the washer  26  placed in the recess  20 D of this cam is denoted  26 G, this face  26 G being opposite the bottom  20 H of the recess. The face  26 G is located at a distance from the plane P measured parallel to the axis X 22  equal to 6 mm. The distance b measured parallel to the X 22  axis between the plane P and the face  20 I of the cam  20  opposite the recess  20 D is equal to 6 mm. There is a slight over thickness of the cam  20  at the part of the face  20 I facing a washer  26 , which gives a clear contact between this face and the washer, with no interference with the face  20 E of an adjacent cam. 
   The value of the distances a and b and the thickness e 20  are such that the cams  20  can be turned over about their plane P, as shown by two of them in  FIG. 2 . 
   The clearance between the adjacent cams  20  in their parts that are not in contact through the washer-spacer  26  is denoted J. This clearance is equal to the distance between the faces  20 E and  20 I facing each other, radially outside the recess  20 D. 
   The clearance  20 G provided in each recess  20 D enables a clean contact between the corresponding washer-spacer  26  with the bottom  20 H of the recess, with no risk of a fillet from pushing the edge  26 A of this washer. 
   In practice, each of the cams  20  fitted on the shaft  22  is provided with a recess  20 D in which a washer-spacer  26  is placed. However, this is not compulsory and it would be possible to image a machine in which only some cams are provided with a recess and a washer. 
   A ring  27  is arranged around the shaft  22  between the bearing  25 A and elements  20  and  26 , the bearing  25 A being in contact with a shoulder  22 G of the shaft. Another ring  28  is placed between the elements  20  and  26  and the end  22 B of the shaft  22 , while a tightening device  29  is provided on this end. By tightening the screws  29 A of the device  29 , it is possible to apply a tightening force F 3  between the rings  27  and  28  parallel to the X 22  axis, in other words axial with respect to the shaft  22 . As shown in  FIG. 3 , the effect of this axial force is to bring the washer  26  firmly into contact with the bottom  20 H of the recess  20 D and in contact with the face  20 I of the adjacent cam  20 . 
   Since the washer  26  bears in contact with the over thickness of the face  20 I of the adjacent cam, the result is firm fixing by adherence or bonding of the side faces  26 G and  26 H of the washer  26  with the face  20 I of the adjacent cam and with the bottom  20 H of the recess  20 D. The elements  20  and  26  are thus fixed in rotation. Furthermore, due to cooperation between the shapes of the teeth  26 C and  26 D and the grooves  22 C and  22 D, the shaft  22  is efficiently fixed in rotation with the washer-spacer  26  and at the same time the shaft  22  and the cam  20 . Therefore, the elements  22 C,  22 D,  26 C and  26 D form complementary relief fixing the shaft  22  and the washer-spacer  26  together in rotation, and enabling the transmission of torque between them. 
   The risks of an angular shift of one or several cams  20  with respect to the shaft  22  are thus avoided as long as the force F 3  is applied. 
   The different washers  26  enable a sort of “secondary resistance” of the fixing torque due to the force F 3  at each of the cams in which there is a recess  20 D. Compared to a machine according to prior art in which the fixing torque by bonding between two cams is approximately equal to the total bond torque due to the axial tightening force divided by the number of cams, the recesses  20 D make it possible to obtain a fixing torque approximately equal to the total torque due to the axial tightening force, at each cam arranged between two washers  26  fixed to the shaft  22  in rotation. 
   Each cam  20  is provided with a groove  20 J on its surface  20 E that extends globally along a radial direction from the axis X 20  and in which a gauge  30  will be fitted as shown in  FIG. 8 . The groove  20 J is formed in an over thickness  20 K with a circular cam section and extends from close to the recess  20 D to the outside edge of this over thickness. 
   During assembly of the machine  10 , each cam  20  is arranged around the shaft  22  and a gauge  30  is then put into place in the corresponding groove  20 J, while a washer  26  is installed in the recess  20 D of the cam  20 , by sliding the teeth  26 C and  26 D in the grooves  22 C and  22 D, which is possible due to the geometry of these projections. The part of the gauge  30  that projects radially from tracks  20 A and  20 B of the cam is then brought in contact with one or several stops  52  forming part of a positioning template  50  of the shaft  22  and the cams  20 . When the gauge  30  is brought into contact with a stop  52 , while the gauge remains in place in the corresponding groove  20 J, the cam  20  is made to pivot around the X 22  axis as shown by the arrow F 4  so that the cam can be oriented with respect to the shaft  22 . The fact that the gauges  30  of the different cams  20  are brought one after the other in contact with one of the stops  52  provides a means of adjusting the relative orientation of the cams  20  with respect to each other as a function of the required harness movement. 
   Only one gauge  30  is shown in  FIG. 8 , so as to make the drawing clearer. In practice, there is one gauge for each cam  20 . 
   When the different cams  20  have been put into position along the shaft  22  and they have been adjusted in angle by bringing their corresponding gauges in contact with one of the stops  52 , these cams are fixed with respect to the shaft  22  and with respect to each other, by putting the device  29  into place and tightening its screws so as to apply the force F 3  that firmly fixes the cams as mentioned above. The gauges  30  are then removed, by pulling them from the corresponding groove  20 J in the radial direction about the X 20  and X 22  axes. The thickness of the gauges  30  is chosen such that each gauge  30  projects slightly outside the groove  20 J in which it is inserted, above the surface  20 E over a height h less than the clearance J when a washer  26  is placed in the recess  20 D. 
     FIG. 9  shows a cam  20  superposed on the cam on which the gauge in  FIG. 8  is fitted, in chain dotted lines. The distance between the face  30 A of the gauge  30  that is parallel to the face  20 E and opposite the bottom of the groove  20 J and the face  20 I of the adjacent cam, is denoted d. The clearance J is equal to the sum of d and h. The geometry of the cams  20  is chosen such that if there is no washer-spacer  26  and when the force F 3  is applied, the clearance J tends to be equal to a value J′ less than the height h. 
   Thus, if a washer-spacer  26  is inserted in the recess of the corresponding cam  20 , the gauge  30  is not in contact with the surface  20 I of the adjacent cam, which enables withdrawal of the gauge  30 , even once the force F 3  has been applied, by sliding along the longitudinal direction of the groove  20 J. On the other hand, if the operator has forgotten the washer  26 , the force F 3  has the effect of bringing the gauge  30  firmly into contact with the surface  20 I of the adjacent cam, which has the effect of jamming the gauge  30 . The operator can then immediately detect that one of the washer-spacers is missing. 
   As shown in  FIG. 2 , the faces  20 E of two adjacent cams  20  may be arranged facing each other, their recesses  20 D and the associated washers-spacers then facing each other. These washers  26  then bear in contact with each other and are fixed in rotation under the effect of the force F 3 . 
   The recess(s)  20 D is (are) made by machining the face  20 E of each cam concerned. They can also be made when the cam is being molded. As a variant, the blank for the recess is made when casting and the recess definition faces, namely its bottom  20 H and its edge  20 F, are machined when the cam is being finished. 
   In a second embodiment of the invention shown in  FIG. 10 , elements similar to the elements in the first embodiment are marked with the same references. The cams  20  shown partially in this Figure are not provided with any recesses, the washer-spacer  26  being compressed by the axial tightening force F 3  between the opposite faces  20 E and  20 I of these cams. In the example shown, the surfaces  20 E and  20 I are each provided with an annular over thickness with an outside diameter slightly smaller than the outside diameter of the ring  26 . However, this is not compulsory and the faces  20 E and  20 I can be completely plane. 
   As above, the drive torque from shaft  22  is transmitted to the washer  26  because its teeth, one of which is marked with reference  26 C, are engaged in the grooves of the shaft  22 , one of which is marked with reference  22 C. The torque is transmitted from the washer-spacer  26  to cams  20  by bonding between the side faces  26 G and  26 H of the washer  26  and the corresponding surfaces  20 E and  20 I of the cams  20  bearing in contact with the washer under the effect of the force F 3 . 
   During assembly of the machine, gauges like the gauges  30  are used, each of the cams  20  are provided with a groove of the same type as groove  20 J. If there is no recess on the cams, care is taken to assure that the thickness of the part of these gauges that project from the grooves is less than the thickness e 26  of the corresponding washer-spacer  26 . 
   The invention is not limited to the embodiments described and it can be improved or modified within the scope defined by the appended claims. For example, a recess could be provided on each of the side faces of a cam. The groove  20 J could be formed on the face opposite the face on which the recess is fitted.