MXPA97000458A - Apparatus for cutting refined fibrous material - Google Patents

Abstract

The present invention relates to an apparatus for cutting fibrous reinforcement material, in relation to an ejector nozzle, comprising at least two feeder rollers and a rotary cutter which is provided with a substantially cylindrical cover surface, with coupling for a number of means of knife and cooperating with a support roller with an elastic surface layer to form a wire narrowing, characterized in that, the cover surface of the cutter is provided with recesses in the form of groove for the fibrous thread, said recesses extend peripherally to along the deck surface between the knife means, allowing the yarn to feed forward by means of feeder rollers at a feed index that deviates from the cutting speed, for the adaptation of the cutting length of the fibro yarn

Description

APPARATUS FOR CUTTING FIBROUS REINFORCEMENT MATERIAL PREVIOUS TECHNIQUE The present invention relates to an apparatus for cutting reinforcing fibrous material in relation to an ejector nozzle, comprising at least two feed rollers and a rotating cutter which is provided with a substantially cylindrical cover surface with couplings for a number of knife means and cooperating with a support roller with an elastic surface layer to form a wire narrowing.

BACKGROUND OF THE INVENTION.

In production controlled by auto-mechanical means, there is usually a great demand for precision in the shipment of raw materials. For example, when fibrous strands are fed to a fiber feeder apparatus, controlled by auto-mechanical means, the feed rate may be approximately 10 meters per second. If a pull occurs at the time of feeding, the thread may break or be damaged, which will cause serious losses in production.

When a fibrous thread is cut, an apparatus of the above-mentioned type is used, each time the fibrous thread is struck by the knife edge of the knife means, the fiber is bent in a V-shape around said fiber. edge while pressing on the elastic layer of the support roller.This operation occurs at a high frequency for a period of time of a few fractions of a second.The mechanical deformation leads to the fracture of the single fibers of the thread. Known for this purpose, they are adapted to cut fibers of a certain length The distance between two cuts usually depends on the distance between the knife means of the cutter, thus, the feeding index of the feed rollers and the cutter is synchronized. It would be desirable to be able to vary the length of the pieces of fiber cut, in an infinitely variable way.In addition, the drawback of this method is that a sudden pull develops in the thread each time a knife means hits it, because the thread momentarily accelerates as it wraps around the edge of the knife. These quick jerks can cause the fibrous thread to cut into the wrong places. THE TECHNICAL PROBLEM Therefore, an object of the present invention is to provide a cutting apparatus which allows an infinitely variable length of the cut pieces of fiber, and which damps the jerks that develop when the edge of the knife means strikes the fibrous thread. THE SOLUTION. For this purpose, this invention is characterized in that the surface of the cover of the cutter is provided with recesses in the form of a groove for the fibrous thread, said recesses extending peripherally along the surface of the cover between the knife means, "- thus allowing the yarn to feed forward by means of feeder rollers at a feeding index that deviates from the speed of the cutter-, for adapting the cutting length of the fibrous yarn.

DESCRIPTION OF THE DRAWINGS Figure 1 schematically shows a fiber feeder device in a side view. Figure 2 shows a plan view, on a somewhat large scale, of the constriction between the cutter and the support roll, and Figure 3 is a section along the line lililí in Figure 2.

DESCRIPTION OF THE MODALITIES The feeder apparatus shown schematically in Figure 1 is used mounted on a self-metering arm, not shown, to feed the fibrous yarn (10) and a binder in the form of powder not shown either, for example, for molds of plastic products. Preferably, the arm of self-mechanical means moves freely in the room and is governed by means of a microprocessor that can be programmable. lf ~. The fibrous thread (10) is placed in the feeder by means of two feeder rollers (11) and (12), which forms a narrowing in the fibrous thread and comprises a first motor driving roller (11) and a second co-rotating roller (12). The roller (12) has a displaceable bearing that is pressed in the direction towards the roller (11) by means of a compression spring (13). The roller (11) is driven in an adjustable speed manner by means of a driving motor not shown. The rollers (11) and (12) feed the fibrous yarn (10) forward in the direction of a compressed air ejector and a tube (15), which bends at approximately 90 ° and emerges in the constriction between a knife roller (16) and a support roller (17). The pieces of fibrous thread (18), cut by the knife roller (16), can be expelled through an ejector tube (19) which is provided with a connection (20) for r * iré compressed. Also, the ejector tube (19) is provided with a connection (21) to a conduit for supplying an agent with a powder binder. The cutter (16) is provided with three knife blades (22) that are distributed with equal space around the periphery of the roller. The cutter (16) can be driven in an adjustable speed manner by means of a driving motor not shown. The support roller (17) is provided with an elastic surface layer (17a) and is maneuverable by means of a tire piston (23). The cutting of the fibrous thread (10) is started by driving the support roller (17) by means of the piston (23) towards the cutter (16). The uncut yarn (10) can be fed through a nozzle (19) when the support roller (17) is removed from the cutter (16). Figures 2 and 3 show the surface of the cover of the cutter (16) which is provided with recesses in the form of a slot (24) for the fibrous thread (10), said recesses extending peripherally along the surface of the cover from a point (25) adjacent to the rear side of the respective knife (22) of the knife (2, as seen in the direction of rotation, towards a point (26) somewhat in front of the next blade (22) of the knife. The recesses make it possible to feed the yarn (10) through the cutting device, without moving the support roller (17) of the roller (16) This allows the variation of the fiber pieces without limits comparatively For example, the feeder rollers (11) and (12) can be driven slower than the cutting device, so that very small pieces of fiber are produced.Alternatively, the feeder rollers (11) and (12) can be driven at a higher speed than the cutting device, so that very long pieces of fiber are produced. Each time the fibrous yarn (10) is cut, a short length is sent forward intermittently at a higher speed than the normal yarn feeding speed. The recesses in the form of a groove allow the formation of a small loosening in the yarn adjacent to its end, at the moment of cutting and until the next cutting knife strikes the yarn at a distance from the free end of the yarn, said loosening it is sufficient to prevent the development of yarn pulls that can lead to breakage without thread control or increased wear of the feeder rollers (11) and (12). The length of this loosening is controlled by the depth of the recesses and is sufficient to compensate for the variations in the pushing force, when the knife strikes the yarn and rolls it while being pressed into the elastic surface layer (17a) of the supporting roll (17) Because the point (25) is located at a certain • "list before the next knife (22), the free end of the thread is caught by the constriction between the cutter (16) and the support roller (17) before the knife of the knife hits the thread 10. The piston (23) is preferably connected to a microprocessor which allows the compensation of the wear in the elastic surface layer (17a) of the support roller (17). is limited to the above-described embodiments, but different variants can be conceived within the scope of the following claims For example, the cutter (16) can be provided with parallel slots (24) for two or more fiber strands (10), in where the cutter can have a corresponding number of support rollers (17), which can be handled individually.

Claims (4)

Claims

1. An apparatus for cutting fibrous reinforcing material, 5 in relation to an ejector nozzle, comprising at least two feeder rollers and a rotary cutter which is provided with a substantially cylindrical cover surface, with couplings for a number of knife means and cooperating with a support roller with a , ** • * elastic surface layer to form a wire narrowing, characterized in that, the cover surface of the cutter is provided with recesses in the form of groove for the fibrous thread, said recesses extend peripherally along the 15 cover surface between the knife means, allowing the yarn to feed forward by means of feeder rollers at a feeding index that deviates from the cutting speed, for the adaptation of the cutting length of the fibrous yarn.

2. An apparatus according to claim 1, characterized in that the recesses extend from a point adjacent to the rear side of the respective knife means, as seen in the direction of rotation, towards a point somewhat opposite the next half of knife.

3. An apparatus according to claim 2, characterized in that the support roller is driven by a control means in the direction towards or from the bearing on the surface of the cutter cover. An apparatus according to claim 3, characterized in that the control means comprises means for compensation of the wear of the elastic surface layer of the support roller.