|Title of Invention||
DETACHING ROLLER DRIVE MECHANISM
|Abstract||This invention relates to the drive system of the detaching rollers of a textile combing machine and a differential gearing is provided for this purpose. The differential gearing receives a rotating movement in one end in the same direction and at a uniform speed and a rocking motion. The resultant output from the differential gearing in the form pilgrim step motion is transmitted to drive the detaching roller. The system comprises an eccentric with its center at location 'e' which is mounted on a stationary eccentric bush having its centre at location *d\ a pull rod with one of its ends pivoted to the eccentric at location 'c' wherein the points *c\ 'd' and 'e' are arranged non collinear.|
FIELD OF THE INVENTION
The present invention, in general relates to an efficient method for the synthesis for obtaining a linkage mechanism with low forces and lower acceleration in detaching roller motion at higher nipping rates. More particularly, this invention relates to a detaching roller drive mechanism.
DESCRIPTION OF RELATED ART
This invention relates to a drive mechanism for the detaching rollers in textile combing machines. In a combing machine, the detaching roller motion has three stages, namely,
1) Fast forward
2) Normal forward or Slow Forward
In the industry parlance, this is called as Pilgrim Step Motion. The Combing methodology espoused, to comb out the fibre tuft presented to the circular comb by the nipper, demands the detaching roller to adopt such a type of motion to effect the Combing process successfully and produce a continuous web. In combing machines, a layer of fibres extending from the nipper assembly is combed out and pushed by the nipper as the nipper swings forwardly on opening to a detaching unit consisting of detaching rollers which convey the fibres forward to the next processing station. The detaching rollers follow a so-called pilgrim-step movement, i.e. the detaching rollers rotate two steps forwardly and one step backwardly. In rotating forwardly, these detaching rollers remove the layer of fibres which have been combed by a circular comb and extend from the nipper and advance the combed layer forwardly. On rotating backwardly, in timed sequence with a second combing cycle, the detaching rollers at first return part of the web removed in the first combing cycle so that the ends of the returned web are placed on the ends of the fibres from the following combed tuft. The
deSching rollers then reverse again and rotate forwardly to remove the second layer of fibres from the open nippers. This last movement corresponds to the detaching movement of the detaching rollers. Thus, the newly attached web is overlapped on the returned web and the two webs become combined with one another under the pressure of the detaching rollers and the adhesion between the fibres of the webs. Thus, the detaching rollers change the direction twice during each combing cycle while following the pilgrim-step movement and remain stationary after detachment for a while until the next combing cycle.
This Pilgrim Step Motion is imparted to the detaching roller, by employing various kinematic mechanisms. The chronological look into the anthology of these mechanisms, reveal that mechanisms like clutch (cutting the drive between Fast forward and backward), Simple Cam and Conjugate cam have been used. Though these mechanisms fulfilled the purpose of their employment, the demands of higher speed and reliability called for a more versatile mechanism, which evolved into the present Linkage mechanism.
In the Cam and the Linkage mechanisms, the Differential gearing produces the Pilgrim Step Motion by acquiring pulsating input from these mechanisms. There are two inputs to the differential gearing. One, the pulsating input from the mechanism employed and other, the uniform motion given to the arm gear. The differential gearing adds these two motions to generate the desired Pilgrim Step Motion. Out of these two inputs to the differential, the pulsating input, which is given by the linkage mechanism plays a decisive and vital role in the motion kinematics as well as motion kinetics of the detaching roller.
The pulsating motion is not continuously imparted to the differential gearing but with a time gap between two pulses. This pulsating input is given to the sun gear of the differential gear unit by a lever of the mechanism. The lever is oscillated about a neutral position. Oscillation in one direction produces Fast forward motion. Oscillation in the opposite direction produces Backward motion. When the lever is kept idle without any oscillation (i.e) in dwell, the normal forward motion occurs, due to uniform rotation of the arm gear.
DESCRIPTION OF PROPOSED ART
There are various mechanisms available to achieve such an intermittently pulsating kinematic behavior. One such simple mechanism is a Four bar with a "Dyad" (two binary links). This four bar with a Dyad constitutes a six bar linkage. In this the coupler link of the four bar mechanism generates coupler curves. Out of these curves an appropriate coupler curve is identified to get the optimum motion kinematics and kinetics of the detaching roller motion curve. The Dyad is then placed such that for a given angle of drive motion the output motion is zero. That is, the coupler curve identified shall have a near elliptical shape with an approximate circular arc segment. An output Dyad is then attached to the coupler point such that the length of the link that is directly pin connected to the coupler point is equal to the radius of the circular arc segment of the coupler curve. During the motion cycle the output link of the Dyad dwells as the coupler point traces the circular arc segment.
The other link of the Dyad is connected to the sun gear of the differential gearing (Oscillating lever). In this linkage mechanism it is possible to obtain the dwell period for 90 deg rotation of the input crank. To increase the time period of the dwell above 90 deg the driven crank is to be rotated in a non-uniform velocity.
This is achieved by employing a double crank drag four bar link. The driver crank of the drag linkage is rotated with uniform velocity and the output driven crank rotates at a non-uniform velocity. This driven crank forms the driver crank of the main four bar linkage mechanism with Dyad. That is, it acts as a common link. This arrangement as a whole becomes an "Eight bar linkage mechanism". This imparts an intermittently pulsating rotational motion to the oscillating lever. This intermittently pulsating motion aids the differential gearing to produce the Pilgrim Step Motion in detaching rollers. This Pilgrim Step Motion can be represented graphically in the form of a curve (displacement vs. input angle). This is called motion curve or motion pattern of the detaching roller.
In the known art of combing machines, in the described common link, the three pin joints lie on a straight line. That is, the non-uniform rotational output of drag link is provided as an input to the crank of the six bar mechanism without any phase difference. With this arrangement the synthesis of the mechanism for the desired motion pattern, is a difficult task.
In high speed combing, the demand for higher nipping rate requires the kinetic factors like force and kinematic factors like acceleration of the detaching rollers to be kept low, so as to reduce the vibration and minimize the forces on the fibres. But there are times where, a linkage with better kinematics with minimum acceleration, will not answer the kinetic factor like minimum forces. In such an event a difficult compromise has to be made on, to choose between the kinematics and kinetics of the linkage mechanism. Because in the event of getting a good motion curve that satisfies the kinematics factors, but with higher generated forces, altering any of the linkage lengths to reduce the forces might have a negative effect on the kinematic behavior and also the motion pattern of the detaching roller.
SUMMARY OF THE INVENTION
The present invention relates to an efficient method for the synthesis for obtaining a linkage mechanism with low forces and lower acceleration in detaching roller motion at higher nipping rates.
These and other objects, features and advantages of the present invention will become more apparent from the ensuing detailed description of the invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 illustrates the linkage mechanism used in prior art.
Figure 2 illustrates tne otner view of the linkage mechanism used in prior art.
Figure 3illustrates the linkage mechanism according to the present invention.
Figure illustrates the other view of the linkage mechanism according to the present invention.
Figure 5 illustrates the arrangement of the drive elements according to the present invention.
Figure 6 illustrates the partial exploded view of the drive elements according to the present invention.
Figure 7 illustrates the exploded view of the drive elements according to the present invention.
Figure 8 illustrates the graphical form of the pilgrim step motion.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail.
In conditions as mentioned above, if an additional controlling parameter is available, in addition to the linkage lengths and angles, the flexibility of the synthesis of the curve will be greatly improved. In the above said mechanism, the common link (i.e. ternary link) has three pin joints in same line. When the central point is shifted by a known distance then a phase difference is induced between the drag link and the six bar linkage mechanism.
When such a phase difference is created in between the double crank drag link
melanism and the driven crank of the six bar, an additional flexibility is obtained in the synthesis of the motion curve. This is a very effective controlling parameter besides the linkage lengths and its angles. This phase difference enables increase in nipping speed of the combing machine thereby resulting in improved combing process.
Figure 1 shows the linkage mechanism used in prior art where the pivot point of the frame (d), centre of the eccentric (e) and the pin joint (c) of pull rod with the eccentric lies on a straight line. i.e. the Line joining the points 'd' and 'c' lie on the centre 'e'.
As suggested in this invention, when the point 'e' is shifted as shown in Figure 3 and 4 , forming a Ternary link 'cde' where the centre of the eccentric (e) is moved such that the hinge of the frame (d) and pin joint (c) of pull rod with the eccentric are not in straight line. The centre of the eccentric (e) shifts such that an angle 0 is formed in 'c-d-e, that is the points c, d, e does not lie in a straight line, then a phase difference is induced in between the 'cd' and 'de\ Varying this phase difference by altering the angle 0, facilitates the synthesis of the linkage easily, for obtaining the desired motion curve with optimized acceleration and Force.
The proposal recommends the angle 0 from 20 deg to 50 deg. And the ratio between lengths CD and DE is from 2.25 to 3.5.
As shown in figures 3 to 7, a circular comb drive shaft (1) which carries the circular comb (not shown) is mounted on a stationary eccentric bush (2) of a combing machine having its centre at location 'd' and the drive shaft (1) is driven by a drive shaft (3) by way of a gear wheel (4) which is mounted on the drive shaft (3) and a gearwheel (5) which is mounted on the circular comb drive shaft (1). The drive shaft (3) receives its further drive from a motor (not shown) via a pulley (6). An adjusting disc (7) which is mounted on the circular comb shaft (1) and is connected with the gearwheel (5) through an adjusting screw (8).
The first end of the pull rod (9) is pivotally connected to the adjusting disc (7) at location b' by means of a crank pin (10). Alternatively, the pull rod (9) can be pivotally connected to the gearwheel (5) without the intermediary of the adjusting
disc ((). The second end of the pull rod (9) pivoted to the eccentric (11) which is having its centre located at (e' and freely mounted on the stationary eccentric bush (2) at location c' through a pin (12). When a rotary movement is imparted to the eccentric (11) from the circular comb shaft (1) through the adjusting disc (7) and the pull rod (9), the same is transmitted by the eccentric (11) to a rocker (13) which is mounted concentrically on the eccentric (11). The first end of the rocker (13) is pivotally connected at location f to the first end of the supporting lever (15). The second end of the supporting lever (15) is pivoted on the nipper drive shaft (36) at location 'g'. The second end of the rocker (13) is pivoted to the first end of the link (16) at location 'h' and the second end of the link (16) pivoted to the first end of the control lever 17 at location T. A shaft (21) of the differential gearing (22) fitted to the second end of the control lever (17) at location *jAs further shown in Fig.7, arm gear (23) of the differential gearing (22) receives a rotating movement in one end in the same direction and at a uniform speed from a gearwheel (24) mounted on the circular comb shaft (1) by way of an intermediate gear (25) mounted on a pin (26) fixed to the machine frame This rotational movement is imparted to a planet gear (27) of the differential gearing (22) which is connected to the arm gear (23) and which rolls around a sun gear 28) fixed on the shaft (21) of the differential gearing (22). The planet gear (27) is further connected with another planet gear (35) to impart rotary motion thereto. This planet gear (35) meshes with and drives a sun gear (29) which is rotatably mounted on the shaft (21) of the differential gearing (22) and connected to a gearwheel (30). The gearwheel (30) drives the detaching rollers (31) through gearwheels (32) and (33) mounted outside the differential gearing (22).
When the eccentric (11) moves, the rocker (13) makes rocking movement which is transmitted through the link (16) at location 'h' to the control lever (17) at location T and makes the control lever (17) to rock. This rocking motion from the control lever (17) and an uniform motion from the circular comb drive shaft (1) is provided as in put drives to the differential gearing (22) which in turn combines the input drives and generates a resultant pilgrim step motion which is transmitted to drive the detaching roller (31).
Figure 8 shows the relationship between the rotation of the input gear (5) and the displacement of the detaching roller. Curve 1 represents the uniform motion from the circular comb drive shaft (1) and curve 2 represents the rocking motion from the control lever (17) which are being input to the differential gearing (22). The resultant pilgrim step motion, which is transmitted to drive the detaching roller (31) is represented by the curve 3.
It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted above.
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.
1. A detaching roller drive mechanism for a textile combing machine comprises a differential gearing (22), circular comb drive shaft (1) which carries the circular comb also being the first input shaft of the said differential gearing (22) and being connected to a drive unit which applies a uniform rotational movement to the said differential gearing (22); an adjusting disc (7) is provided which applies an additional rotational movement to the said differential gearing through an eccentric (11), the centre of which is located at location le' mounted on the stationary eccentric bush (2) at location (d'; the said adjusting disc (7) and the first end of the pull rod (9) being pivoted at location 'b'; the second end of the pull rod (9) being pivoted to the eccentric (11) at location (c'; the said eccentric (11) further carries a rocker (13) the first end of which is pivoted to the first end of the support lever (15) at location 'f and the second end of the rocker being pivoted to the first end of the link (16) at location 'h'; while the second end of the support lever (15) being fixed on the nipper drive shaft (36) at location lg\ the second end of the link (16) being pivoted to the control lever (17) at location T for the transfer of the rotational movement of the eccentric as the second input to the differential gearing through the shaft (21) mounted on the control lever (17) at location 'j' characterized in that the points 'c' 'd' and 'e' are arranged non collinear.
2. A detaching roller drive mechanism for a textile combing machine as claimed in claim 1 wherein said three points 'c\ (d' and (e' can be adopted by a known distance to induce a phase difference in between cd & de.
3. A detaching roller drive mechanism for a textile combing machine as claimed in claim 2 wherein said phase difference is between 20deg to 50deg.
|Indian Patent Application Number||2031/CHE/2007|
|PG Journal Number||45/2011|
|Date of Filing||11-Sep-2007|
|Name of Patentee||LAKSHMI MACHINE WORKS LTD.|
|Applicant Address||LAKSHMI MACHINE WORKS LTD PERIANAICKEN PALAYAM COIMBATORE 641020|
|PCT International Classification Number||D01G19/26|
|PCT International Application Number||N/A|
|PCT International Filing date|