Abstract:
A device for balancing, tightening, and guiding an endless apron in the drafting part of a spinning frame comprised of a base plate in the shape of an angle bar with acute angle having a guiding element on one side thereof, a sliding base equipped with an automatic balancing and tightening mechanism on its lower end which is guided by the above said guiding element, and integrally incorporating thereinto a plate spring having a spring latch. A pressing element is provided between the sliding base and the back surface of the base plate, and a locking lever is slidably disposed at right angles to the guiding element.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention primarily relates to a guiding means for an endless apron provided in the drafting part of a spinning frame, and further, to a guiding means for an endless belt in the feeding mechanism of, for example, a printing machine, duplicator, precision packaging machine, film processor, and the like. 
     2. Description of the Prior Art 
     FIG. 1 is an illustration showing a typical apron zone of a long apron type drafting device which comprises such components as a bottom roller BR and a top roller TR, both being disposed on a roller stand RS which supports a roller, a cradle CR, a tensor bar TB, a tension guide TG pressed by a tension lever TL in the direction of the arrow, a top apron TA and a bottom apron BA, in addition to a weighting arm WA. 
     However, the above said apron guiding device in respect of performance and operability for tightening, balancing and guiding the bottom apron, as well as performance of the tensor bar itself and operability in maintenance thereof, has not proved satisfactory. 
     SUMMARY OF THE INVENTION 
     This invention relates to an apron guiding device, being provided with a novel mechanism, eliminating disadvantages found in the conventional long apron type, and on the other hand, utilizing advantages thereof, which comprises a base plate having a guide means on one side of an angle bar with acute angle, a sliding base guided by the guide means, an automatic apron balancing and tightening means provided on the end of said sliding base, and a pressing means provided between a back surface of the sliding base and the base plate. 
     The apron guiding device according to the present invention has been able to enhance increasingly the function and capability of apron guiding devices by eliminating the various drawbacks in the existing devices and, further, adding an automatic apron balancing and tightening means thereto. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an illustration showing a typical apron zone of the long apron type drafting device in a spinning frame; 
     FIGS. 2a and 2b illustrate perspective views of the relationship between the base plate, sliding plate and locking lever, all of which comprise the main part of the device according to the invention; FIG. 2a showing an open state and FIG. 2b showing a closed state. 
     FIGS. 3a and 3b illustrate plan views corresponding to FIGS. 2a and 2b; FIG. 3a showing an open state and FIG. 3b showing a closed state; 
     FIGS. 4a, 4b, 4c, 4d, 4e and 4f illustrate changes in positional relationship between the spring latch of the sliding base and the locking lever; 
     FIG. 5 is a perspective view of the locking lever; 
     FIGS. 6a, 6b and 6c illustrate the relationship between the sliding base and the tension slider; 
     FIG. 7 illustrates a modification of the embodiment of FIGS. 6a, 6b and 6c; 
     FIGS. 8a and 8b are plan and elevational views, respectively, illustrating another modification of the embodiment of FIG. 6. 
     FIGS. 9a and 9b illustrate the device completely assembled according to this invention; FIG. 9a showing an open state and FIG. 9b a closed one; 
     FIGS. 10a and 10b illustrate modifications of the embodiments in FIGS. 9a and 9b, FIG. 10a showing an open state and 10b showing a closed one; 
     FIG. 11 shows a modification of the tension slider; 
     FIG. 12 shows a modification of the latch spring; and 
     FIG. 13 shows another modification of the latch spring. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIGS. 2 and 3, the sliding base B is provided with a guiding means AT for automatically balancing, tightening and guiding the apron at the lower end thereof, and in addition, integrally incorporating a plate spring S forming a spring latch SL at the middle part of the surface thereof. The sliding base B is held between a pair of slide guides SG and is slidable only along the line Y--Y&#39;, the slide guides being provided on the surface of a base plate F which is shaped like an angle bar with acute angle and adapted to provide a surface SR for movement of the sliding base. 
     A locking lever L is provided which is channel-shaped () in section and guided through a pair of guide grooves 1,1 provided in the pair of said slide guides SG so as to be slidable only along the axis X--X&#39; at right angles to the axis Y--Y&#39;. The locking lever L is supported in such a way that it is in contact with the upper surface of the sliding base incorporating the plate spring S and is adapted to be capable of, when required, catching and holding the spring latch SL inside the  -shaped channel part thereof. Sliding of the locking lever L is controlled within a fixed range by an appropriate device not shown herein. A pressing spring SP, which presses the sliding base B toward the lower side of the drawing, lies between the backside of the sliding base B and the back surface BS of the base plate F in such a state as expanding its ends toward the spring-touching surfaces 2 and 3 of both the base plate and the sliding plate, respectively. This spring may be replaced, when required, with either pneumatic, hydraulic, magnetic or electric pressing means. On the upper surface of the sliding base B are formed upwardly protruding flanges 6 and 7 facing respective hanging sides 4 and 5 of the locking lever L. The hanging sides 4 and 5 occupy a position between the protruding flanges 6 and 7 and limit the range of sliding distance of the sliding base B. In other words, movement of the sliding base B along the axis Y--Y&#39; is limited in the upward direction by contact of the lower flange 6 with the locking lever or bar L, and, similarly, downward sliding movement is limited by contact of the upper flange 7 with the same lever L. 
     FIGS. 2a and 3a show the sliding base B protruded from the base plate F, i.e., the apron is tightened, wherein the spring latch SL of the plate spring S incorporated in the sliding base B lies outside the channel of the locking lever L. FIGS. 2b and 3b show the sliding base B drawn back into the base plate F thereby compressing the pressing spring SP, i.e., the apron is loosened, wherein the spring latch SL lies inside the channel of the locking lever L, being withheld by the hanging side 4 of the locking lever L and, therefore, keeping the sliding base B withdrawn. A cut part C is provided in the hanging side 4 of the locking lever L, allowing the spring latch to pass therethrough. In the position shown in FIG. 3b, by shifting the locking lever L to the left side, the cut part C of the locking lever L is brought into alignment with the spring latch SL, and the sliding base B is permitted to assume the position shown in FIGS. 2a and 3a under the action of the pressing spring SP as discussed above. After the sliding base B protrudes from the base plate, the locking lever L is shifted to the right. As shown in FIG. 3a, by thrusting the sliding base B along the axis Y--Y&#39; against resilience of the pressing spring SP, the spring latch SL passes beneath the bottom end of the hanging side 4 and is withheld therein. 
     FIGS. 4a,4b,4c,4d,4e and 4f show changes in the positional relationship between the locking lever L and the spring latch SL. In the position shown in FIG. 4d, where the guiding means is functioning in a normal state, if the sliding base B is thrust upwardly against the pressing spring SP, the positional relationship between the sliding base B, spring latch SL and locking lever L is progressively changed as shown in FIGS. 4a,4b and 4c, where finally the locking lever L is immovably held from movement along the axis Y--Y&#39;. That is, in the position shown in FIG. 4c, the spring latch SL is held within the channel by the hanging side 4. 
     For releasing the latch, displacement of the locking lever L as shown in FIG. 3f is necessary. To this end, the locking lever L is shifted to the left as shown in FIG. 3b until the cut part C of the locking lever L is aligned with the spring latch SL, thus corresponding to the position illustrated in FIG. 4f. After the locking lever L is positioned as shown in FIG. 4f, the positional relationship between the sliding base B, spring latch and locking lever is progressively changed as shown in FIGS. 4d, 4e and 4f, wherein the sliding base B returns to its initial state where the guiding means functions normally. So long as the sliding base B remains positioned as shown in FIG. 4d, the sliding base B will tighten and guide the apron correctly, offering resistance to compressive force of any nature generated by various types of casual phenomena and exerted upon the pressing spring SP. 
     FIGS. 6a, 6b and 6c illustrate a guide means AT for tightening and guiding the endless apron fitted to the tip of the sliding base B. The guide means AT comprises the sliding base B serving as a foundation; a tension slider TS and the spring 8. The tension slider is U-shaped in section, positioned on and extending forwardly from the front end portion of said sliding base B. The spring 8 resiliently urges said tension slider TS from the front end portion of the sliding base B and at the same time supports the tension slider TS rotatably both leftward and rightward. A circular cut-away portion 9 is provided at the middle of the front end of the sliding base B as shown in FIG. 6a, and on both sides of the cut-out portion 9 are guiding protuberances 10, 10. The guiding protuberances 10,10 are provided for guiding and controlling sliding movement of the tension slider TS along the axis Y--Y&#39;. FIGS. 6b and 6c illustrate control holes 11,11 provided on the tension slider TS. The control holes 11,11 come into engagement with the guiding protuberances 10,10 when the slider is coupled with the sliding base B. The spring 8 has a circular portion 8&#39;  at a mid-portion thereof, serving as a center of turning in both directions, and expands both ends 8&#34;, 8&#34; in the left and right directions. Under action of the spring 8, the tension slider TS is kept resiliently extended from the front edge of the sliding base B for balancing, tightening and guiding the apron. 
     FIG. 7 illustrates a modified embodiment of the guide means AT of the present invention. A semi-circular protuberance 16 is formed at the middle of the cut-away portion 9 provided on the front edge of the sliding base B. A curved portion 8&#34;&#39; is provided between two other curved portions 8&#39; and 8&#39; of the spring 8. The curved portion 8&#34;&#39; is positioned in contact with the outer edge of a protuberance 16 so that the tension slider TS may turn in both directions around the contact part. 
     FIG. 8 illustrates a further embodiment of the guide means AT. Sliding movement of the tension slider TS along the axis Y--Y&#39; depends on the sliding function of the sliding base B itself. The tension plate TP is U-shaped in section and positioned on the tip of the sliding base B. The tension plate TP is adapted to be turnable around a rotatable axis 12 for balancing, tightening and guiding the apron. 
     FIG. 9 illustrates a device for guiding the endless apron in the form of a triangle, wherein one end of a bracket BKT is secured to a frame GR. The bracket BKT forms a base plate F which functions as a foundation to which the sliding base is secured. The tension slider TS is mounted onto the tip of the sliding base B, i.e., a point where the apron AP changes its running direction. The apron AP is guided in the form of a triangle and tensioned by a driving roller R that revolves around a center O 1  provided on the bracket BKT secured to the frame GR, the guide roller N revolving around O 2 , and the balancing and tightening means AT. Guiding portions 13 are provided on both sides of the tip of the sliding base B so as to move the apron sideways to be guided to a correct path that extends on both sides of a certain center line. The apron guide 14 is in slight contact with the reverse side of the apron AP and separates the apron from the plate F, thereby mitigating acuteness of angle with which the running direction of the apron is changed and preventing the apron from having a permanent curving tendency as well as from sticking of dust to the reverse side thereof. As shown in FIG. 9b, the balancing and tightening means AT at the tip of sliding base B is so constructed as to be received in the cut part of the base plate F when the sliding base B is drawn back into the base plate F and retained at the recessed portion. Therefore, each of a group of aprons that surrounds its respective base plate can freely be handled independent of the balancing means, which permits easy servicing and maintenance of the balancing means. 
     FIG. 10 illustrates the apron enclosing the driving roller R and the sliding base B including the balancing means AT mounted on the base plate F which is integrally secured to the frame GR. 
     FIG. 11 illustrates the tension slider TS to the end of which a guide roller M is secured. 
     FIG. 12 illustrates another embodiment of the spring latch on the spring plate S, wherein an additional spring latch SLP is positioned opposite to and symmetrical with respect to a spring latch SLM for limiting the distance of displacement of the device along the axis Y--Y&#39; during the period of normal operation thereof. In addition, the spring latch SLM serves the same function as that of the spring latch SL. According to this method, an experiment was performed in an attempt to remove the major cause of apron breakage and, as a result, a significant benefit has become apparent therefrom. 
     Further, as shown in FIG. 13, latching operation may be performed in a manner similar to the above by mounting a latch spring SL&#39; to the sliding base B and utilizing a hook portion 16 at the tip of the latch spring SL&#39;, instead of using the spring plate. 
     Preferred embodiments of this invention having some characteristics and other currently contemplated modifications have thus far been described as above, and it will be apparent to those skilled in the art that correction and/or modification thereof may be resorted to without departing from the spirit of this invention. 
     Accordingly, embodiments of this invention as described above are to be considered as describing and not limiting this invention, and therefore, it is to be understood that the scope of this invention is defined in the appended claims, and all modifications included within the spirit and scope equivalent to said claims are intended to be included within said claims.