Device for cutting a tail-end of a yarn package formed on a base portion of each spindle in a textile machine
SUMMARY OF THE INVENTION 
     The present invention relates to an improved device for automatically cutting a tail-end of a yarn package formed on a base portion of each spindle of a textile machine, when the yarn packages are doffed from the respective spindles. 
     It is well known that, when yarn packages of full size are doffed from the respective spindles of a textile machine, such as a ring spinning frame or twisting machine, the ring rail is firstly displaced to its lowermost position so as to form a tail-end winding on a base portion of each spindle of the textile machine. Next the yarn packages are doffed from the respective spindles in such a condition that a yarn portion connecting the yarn package and the tail-end winding is cut. 
     To carry out the above-mentioned cutting operation, several cutting devices have been introduced. However, it is our opinion that these conventional cutting devices are not acceptable because perfect cutting of the yarn is not always achieved. For example if a cutting device utilizing a cutting principle based on severing is used to carry out the cutting operation on a textile machine producing a yarn package of a synthetic filament, the filament yarn is elongated by the severing action and it is impossible to cut the filament yarn perfectly. Further, in the case of utilizing a cutting device provided with a knife edge cutter, if the yarn material of the yarn package is a synthetic filament, since the cutting operation is carried out by contacting the yarn against the knife edge in an angular contacting condition, perfect cutting of the filament yarn is frequently not accomplished. 
     The principal object of the present invention is to provide an improved device for cutting a connection between a yarn package and a tail-end winding package, formed on a base portion of each spindle of a textile machine, which eliminates the above-mentioned drawbacks of a conventional cutting device. 
     Another object of the present invention is to provide an improved device for cutting a connection between a yarn package and a tail-end winding formed on a base portion of each spindle, wherein a replaceable cutter is positioned. 
     To attain the purpose of the present invention, the cutting device according to the present invention is provided with a guide member having at least one recess for restricting the yarn passage between the yarn package and the tail-end winding, in such a condition that the yarn passage is at an inclined angle to a spindle shaft, and a cylindrical crip member, for forming a tail end yarn portion thereon is formed at a base portion of the spindle at a position below the above-mentioned guide member. The cylindrical crip member is provided with a knurled cylindrical surface and a ring shaped cutter is replaceably mounted on the above-mentioned guide member in stable condition. 
    
    
     BRIEF EXPLANATION OF THE DRAWINGS 
     FIG. 1 is a schematic front view of a cutting device mounted on a spindle according to the present invention; 
     FIG. 2 is an enlarged front view of the cutting device shown in FIG. 1; 
     FIG. 3 is a schematic front view of the cutting device, partly in section, shown in FIG. 1; 
     FIG. 4 is a schematic plan view of the cutting device mounted on the spindle according to the present invention; 
     FIG. 5 is a schematic plan view of a ring shaped cutter utilized for the cutting device shown in FIG. 1; 
     FIG. 6 is a schematic side view of the ring shaped cutter shown in FIG. 5; 
     FIGS. 7 and 8 are explanatory front views of the cutting device according to the present invention when the ring shaped cutter shown in FIGS. 5 and 6 is mounted thereon, and; 
     FIGS. 9 and 10 are explanatory front views of another type of cutting devices according to the present invention. 
    
    
     DETAILED EXPLANATION OF THE INVENTION 
     Referring to FIGS. 1, 2, 3, 4, 5, 6, 7 and 8, the cutting device according to the present invention comprises a round guide member 3 mounted on a base portion of a spindle 1, a cylindrical crip member 6 coaxially secured to the spindle 1 at a position right below the guide member 3 and a thin ring shaped cutter 7 coaxially mounted on the guide member 3. The cutter 7 is provided with a circular knife edge 7a as shown in FIGS. 4, 5 and 6. The point angle of this knife edge is represented by θ 1  in FIG. 6. The crip member 6 is provided with a knurled surface 5 and the diameter of the crip member 6 is smaller than the diameter of the guide member 3. The knurled surface 5 of the crip member 6 permits the winding of the tail end of a yarn thereon. The guide member 3 is provided with a round recess 10 which is capable of receiving the ring shaped cutter 7 therein. To hold the cutter 7 in the round recess 10 in a stable condition, an inside wall 11 of the recess 10 is inclined inward from the bottom of the recess 10 to the top edge of the recess 10. That is, the inside wall 11 is tapered toward the inside of the round recess 10 from the bottom of the recess 10 to the top edge of the recess 10 with a taper angle θ 2 . To hold the cutter 7 in the recess 10 of the guide member 3 in a secured condition, it is preferable to form the point angle θ 1  of knife edge of the cutter 7 in such a condition that the angle θ 1  is substantially identical to the taper angle θ 2 . 
     In this embodiment of the cutting device, a plurality of cut-out grooves 2 are formed at the circumferential wall of the guide member 3 so as to project the knife edge 7a of the cutter 7 from the recesses 2 as shown in FIG. 4. According to our experimental texts, it was found that the intervening distance between two adjacent cut-out grooves 2 must be defined so as to permit acceptance therein of a straight yarn portion of a connection between a yarn package c and a tail end winding 9, when the ring rail (not shown) is displaced to its lowermost position at the time of carrying out the doffing operation. 
     Further, the knurled surface 5 of the cylindrical crip member 6 effectively prevents slipping of a tail-end winding of a yarn, which forms thereon, along the cylindrical surface of the crip member 6 so that the tail end of the yarn is tightly wound on the cylindrical crip member 6. Consequently, the straight portion of the tail-end yarn can be urged to the sharp knife edge of the cutter 7 and cut thereby. 
     The function of the cutting device according to the present invention is hereinafter explained in detail, with reference to the above-mentioned drawings. 
     When a full size yarn package c is formed on each spindle 1 of a textile machine such as a ring spinning frame or ring twisting frame, firstly, a ring rail 13 is displaced to its lowermost position while each spindle 1 is rotating by its inertia. According to the above-mentioned displacement of the ring rail 13, a spiral winding of yarn is formed on the yarn package c and the tail-end winding 9 is formed on the crip member 6 of the cutting device so that a straight yarn portion 8a is formed along a passage between the bottom end of the spiral winding of yarn on the yarn package c and the tail-end winding 9 in such a way that the straight yarn portion 8a passes through one of the above-mentioned cut-out grooves 2. When the straight portion 8a of the tail end yarn is introduced into the cut-out groove 2, the straight portion 8a is urged to the knife edge of the cutter 7 in an inclined condition to the cutting edge. Further, since the outside diameter of the cylindrical portion of the crip member 6 is smaller than the yarn guide member 3, the above-mentioned yarn portion 8a of the tail-end yarn between the yarn package c and crip member 6 is maintained in a straight condition and the yarn is forced to knife edge of the cutter 7. 
     When the full size yarn package c is taken from the respective spindles 1, since the yarn package c is displaced upward, the yarn portion 8a, which extends between the spiral winding of the yarn package c and the tail-end yarn winding 9 wound on the crip portion 6, is laterally displaced toward the x direction shown in FIG. 2. During the above-mentioned lateral displacement of the straight yarn portion 8a, since a yarn portion adjacent to the tail-end winding 9 engages the bottom edge 3a of the cut-out groove 2, the yarn portion 8a is turned around the bottom edge 3a and, consequently, the yarn portion 8a is displaced toward the x direction while being urged against the knife edge of the cutter 7. In this condition, the yarn portion 8a is by the knife edge 7a bent as shown in FIG. 3, while, the free lateral displacement of the yarn portion 8a is restricted by the bottom edge 3a of the cut-out groove 2. Accordingly, a very effective shearing force is applied to the yarn portion 8a so that the cutting of the straight yarn portion 8a can be carried out perfectly. To create the above-mentioned very effective shearing force, the relative position and size of the guide member 3 to the crip member 6 is an important factor. That is, it is necessary that the guide member 3, having a laterally larger size than the crip member 6, be mounted at a position right above the crip member 6. Further it is necessary to stably hold the cutter 7 on the guide member 3 in a replaceable condition. This is because, if the knife edge 7a of the cutter 7 is worn during a long period of utilization thereof, the used cutter 7 should be replaced by a fresh cutter 7. 
     Referring to FIGS. 4, 5, 6, 7 and 8, the cutter 7 is a ring shaped one provided with a cut-out portion 7b and, therefore, the cutter 7 is capable of contracting radially. According to the above-mentioned construction of the cutter 7, when the cutter 7 is mounted on the guide member 3, the cutter 7 is radially contracted and inserted into the recess 10 of the guide member 3 in such a way that the cutter 7 contacts the inside wall 11 of the recess 10. When the above-mentioned insertion is completed, the cutter 7 is expanded radially so that the cutter 7 is stably held by the inside wall 11 of the recess 10. To attain very effective holding of the cutter 7 by the guide-member 3, the inside wall 11 of the recess 10 is formed in such a condition that the radial space defined by the inside wall 11 decreases toward the upward direction, in other words, the recess 10 is formed in a conical shape having a smaller top portion and a larger bottom portion. In this condition, a ring shaped groove is formed between the inside wall 11 and the bottom plane of the recess 10. This ring shaped groove is provided with a tapered side wall which is the above-mentioned inside wall 11. If the taper angle of the above-mentioned tapered side wall is identical to the point angle θ 1  of the knife edge 7a of the cutter 7, the cutter 7 can be held by the above-mentioned ring shaped groove in a very stable conditon. 
     When it is required to take-out the cutter 7 from the recess 10 of the guide member 3, the ring shaped cutter 7 is firstly radially contracted and then taken from the recess 10 of the guide member 3. To carry out the above-mentioned taking-out operation very easily, a pair of small apertures 12 are formed in the cutter 7 as shown in FIG. 5. In this embodiment, an auxiliary device for contracting the cutter 7 is utilized. This auxiliary device is a tool similar to a pinchers, provided with a pair of projections which can be inserted into the above-mentioned small apertures 12, respectively. When the cutter 7 is taken-out of the recess 10 of the guide member 3, the above-mentioned projections of the auxiliary device are inserted into the small apertures 12 of the cutter 7, respectively, the distance between the projections is forced to decrease by operating the auxiliary device and, then, the cutter 7 is taken from the recess 10 of the guide member 3. 
     The above-mentioned conical recess 10 of the guide member 3 can be easily made by the conventional molding operation, if a plastic material is utilized for making the guide member 3. If a metallic material is used for the guide member 3, the following step for forming the recess 10 of the guide member 3 may be applied. Referring to FIGS. 9 and 10, the cylindrical recess 10 is firstly formed in the guide member 3 in such a condition that a plurality of thin upwardly projected edge portions 3b are formed (FIG. 9). After mounting the cutter 7 into the recess 10, these edge portions 3b are bent inward so as to hold the cutter 7 by the edge portions 3b as shown in FIG. 10. If the cutter 7 is made from an elastic material, a perfectly round ring cutter may be utilized, because, such cutter can be mounted on or taken from the guide member 3 without difficulty due to its elasticity.