US3722260A

US3722260A - Method and apparatus for detecting weight variations of a sliver on spinning preparatory machines

Info

Publication number: US3722260A
Application number: US00121333A
Authority: US
Inventors: P Staheli
Original assignee: Maschinenfabrik Rieter AG
Current assignee: Maschinenfabrik Rieter AG
Priority date: 1970-03-11
Filing date: 1971-03-05
Publication date: 1973-03-27
Anticipated expiration: 1990-03-27
Also published as: DE2110901A1; GB1338441A; CH520794A; FR2084472A7

Abstract

A method and apparatus for detecting weight variations of a sliver on spinning preparatory machines, such as cards, draw frames and similar machines, at which the sliver passes through the channel or duct of a sliver funnel or trumpet. According to the invention, the sliver is initially condensed in the sliver funnel duct in order to expel entrained air. Immediately thereafter the sliver is again expanded and by virtue of such expansion there is produced at the expansion zone a pneumatic vacuum which is proportional to the weight variations of the throughpassing sliver. This generated vacuum is then advantageously employed to control an amplifier for performing a desired operation, namely a measuring or control.

Description

United States Patent 91 Staheli Mar. 27, 1973 [75] Inventor: Paul Staheli, Wilen bei Wil/I'haurgau, Switzerland [73] Assignee: Rieter Machine Works, Ltd., Winterthur, Switzerland [22] Filed: Mar. 5, 1971 [21] Appl.No.: 121,333

[58] Field of Search ..73/37.5-37.8, 160; 250/219 TL, 219 S; 19/239, 240

[ 56] References Cited UNITED STATES PATENTS 7/1958 Lewiset al. ..l9/240 l/l960 Brown ..l9/239 3,035,313 5/1962 Naegeli etal ..l9/l57 X 3,088,175 5/1963 Akira Aoki... ..l9/240 3,435,673 4/1969 Felix ....73/16O 3,283,564 11/1966 Biddison, Jr ..73/37.7 3,411,352 11/1968 Stoller ..73/160 Primary ExaminerL0uis R. Prince Assistant ExaminerFrederick Shoon Attorney-Wemer W. Kleeman ABSTRACT A method and apparatus for detecting weight variations of a sliver on spinning preparatory machines, such as cards, draw frames and similar machines, at which the sliver passes through the channel or duct of a sliver funnel or trumpet. According to the invention, the sliver is initially condensed in the sliver funnel duct in order to expel entrained air. Immediately thereafter the sliver is again expanded and by virtue of such expansion there is produced at the expansion zone a pneumatic vacuum which is proportional to the weight variations of the throughpassing sliver. This generated vacuum is then advantageously employed to control an amplifier for performing a desired operation, namely a measuring or control.

11 Claims, 2 Drawing Figures PATENTEUmznma INVENTOR.

PHUL 575,451.:

wan/6R u. mac/ml! 1-7 FOIPNE y METHOD AND APPARATUS FOR DETECTING WEIGHT VARIATIONS OF A SLIVER ON SPINNING PREPARATORY MACHINES BACKGROUND OF THE INVENTION The present invention relates to a new and improved method and apparatus for detecting weight variations of a sliver on spinning preparatory machines, such as and/or control operation.

cards, draw frames and similar machines, at which a sliver passes through the duct of a sliver funnel or trumpet.

In spinning preparatory machines of the general type mentioned above equipment has recently become known for controlling the draft ratio in drafting arrangements. With such equipment the static air pressure in a sliver duct possessing a funnel-like narrowing cross-section area is measured by means of a connection duct penetrating through the funnel wall in order to utilize the pressure variations caused by the weight or density variations of a sliver passing through the funnel. In such arrangements, however, it was found that, together with the air surges or impulses entering the connection duct dust particles also penetrate into the measuring duct where they are deposited, so that the duct eventually can be blocked. In order to eliminate or minimize this drawback it was already proposed to generate a slight overpressure and a corresponding slight air stream into the funnel. This air stream was just sufficient to avoid penetration of dust-loaded air into the measuring duct as the pressure in the funnel increases. Maintenance of such pressure in the measuring duct system at the precise level needed for ensuring reliable measuring results, however, can require increased susceptibility to disturbances of the measuring device as well as considerable cost of the measuring device, depending upon the measuring accuracy to be achieved. Another device also proposed in the art and provided with an air circulation system exhibits the same disadvantage.

SUMMARY OF THE INVENTION Therefore, there is still present a real need in the art for an improved method of, and'apparatus for, detecting weight variations of a sliver on spinning preparatory machines which is not associated with the aforementioned drawbacks of the prior art techniques and equipment. Hence, a primary object of the instant invention is to provide just such method and apparatus structure which effectively and reliably fulfills the existing need in the art.

Another and more specific objective of the present invention is directed towards eliminating the aforementioned prior art disadvantages discussed above, in order to achieve as maintenance free as possible detection of sliver weight variations, and to achieve a most uniform sliver weight and quality, while at the same time increasing the productivity of the machines.

Now, in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the new and improved method of the present invention is manifested by the features that the sliver is first con-' densed in a sliver funnel duct in order to expel or squeeze-off the entrained air, and directly thereafter the condensed sliver is again permitted to expand, so that in the expansion zone there is generated a pneu- The apparatus for implementing the aforesaid inventive method comprises a sliver funnel possessing a sliver duct, the cross-section of this sliver duct, as viewed in the direction of throughput of the sliver, decreases from the entry of the sliver intothe inlet side of the sliver funnel to a minimum cross-section which is intermediate the inlet side and the outlet'side of the sliver funnel. Thereafter, the cross-section of the sliver duct then increases towards the outlet side of the sliver funnel where the sliver exits, and at the region of increasing cross-section there is provided a connection duct or channel for an amplifying device which penetrates through the wall of the sliver funnel.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawing wherein FIG. 1 is a longitudinal sectional view of a first embodiment of inventive sliver funnel for the performance of the method aspects of this invention; and

FIG. 2 is a longitudinal sectional view of a second embodiment of sliver funnel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the exemplary embodiment according to FIG. 1 a sliver funnel 1 will be seen to contain a throughpassage channel or duct 2 through which passes the sliver 3 to be processed. The cross-section of duct 2 initially decreases, as viewed in the direction of the sliver throughput indicated by

arrows

5 and 5 respectively from the sliver entry or inlet side 4 substantially like a funnel or trumpet, to a minimum cross-section. This minimum cross-section constitutes the narrowest point of the sliver duct 2, the cross-section of which immediately thereafter uniformly increases towards the sliver outlet or exit side 7. This enlargement is formed by the wall section 8 of the funnel wall 20 which widens or diverges in the direction of the sliver throughput. At a suitable location at the region of this diverging wall section 8 of the funnel wall there is provided a connection channel or duct 9 which penetrates the funnel wall- 20, this duct 9 is equipped with a connecting nozzle 10 or with another suitable connecting element at the outside of the funnel 1, so that such funnel can be connected to a suitable vacuum-amplifying device 1 l.

The alternative embodiment depicted in FIG. 2 differs from the one described above merely in that at the merging or entry point of the connection or measuring duct 9 into the exit or outlet end region of the sliver channel or duct 2 formed by the wall section 8 there is provided a slight recess 12 extending partially along, or along the full circumference, and which can be formed as a groove 13 in order to increase the pressure equalization at this location and to improve the response sensitivity of the measuring or controlling devices.

The sliver generally indicated at 3, passing through the sliver duct 2 from the sliver inlet 4 is first condensed in a known manner, and at the same time most of the entrained air is expelled. From the narrowest cross-section 6 to the sliver outlet 7 the sliver is again expanded, under the influence of the fiber elasticity, at the region of the widening wall section 8. Thus, in this region there is generated a vacuum or negative pressure which is proportional to the weight variation of the throughpassing sliver 3. For the purpose of amplifying the vacuum variations generated in this expansion zone, there may be provided an amplifier 11 of the type commonly referred to as a fluid amplifier" and which has become known in the past few years and has proven to be particularly advantageous. In both of the embodiments considered above the enlargement of the sliver duct 2 formed by the funnel wall section 8 from the narrowest location or point 6 to the sliver outlet end 7 should not exceed the natural enlargement of the sliver cross-sectional area caused by the fiber elasticity.

In order to ensure for an effective negative pressure or vacuum with appropriate suction force or action, the diverging funnel wall section 8 forming the enlargement of the sliver duct 2 should form an opening angle a not exceeding approximately 25. The optimum angle or, however, not only depends upon the elasticity or, more generally, on the type of fibers processed, but also e.g. on the degree of condensing as the sliver passes through the funnel duct, on the sliver throughput speed, on the type and distance of calander rolls possibly used for taking-off the sliver, and on similar influences. Thus, during experiments using different arrangements, particularly suitable opening angles a were found in the range of 6 to 16.

Furthermore, in order to prevent any deposit of dust particles at or in the entry or opening of the measuring duct 9 into the expansion zone of the sliver duct 2 formed by the funnel wall section 8, the entry angle B formed by the measuring duct 9 and the sliver throughput output direction indicated by the arrows and 5' respectively should preferably not exceed 90, a range of 30 to 85 being particularly preferred. During experiments with various entry angles [3, optimum results were found in the range of 30 to 85. The crosssection of the sliver duct 2 of the funnel 1 can be chosen circular or non-circular. Furthermore, the sliver throughput direction through the funnel 1, or the input and output directions indicated by the

arrows

5 and 5, can deviate from a straight line.

While 7 there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

What is claimed is:

1. A method of detecting weight variations of a sliver on spinning preparatory machines, such as cards, draw frames and similar machines, at which the sliver passes through the duct of a sliver funnel, comprising the steps of: initially condensing the sliver in the duct of the sliver funnel in order to expel air entrained by the sliver, immediately thereafter expanding the condensed sliver in an expansion zone, generating in the expansion zone a pneumatic vacuum which is proportional to the weight variations of the throughpassing sliver, and utilizing the generated pneumatic vacuum for controlling an amplifier. v

2. An apparatus for detecting weight variations of a sliver, comprising a sliver funnel provided with a sliver throughpassage duct extending between a sliver inlet side and a sliver outlet side of said sliver funnel, said duct decreasing in cross-section in the direction of throughput of the sliver to a location of minimum cross-section disposed intermediate said inlet side and said outlet side, said duct increasing in cross-section from said location of minimum cross-section toward said outlet side to define therebetween a region of increasing cross-section of the duct, and a connection duct for an amplifying device provided at said region of increasing cross-section, said connection duct penetrating through the wall of said sliver funnel.

3. The apparatus as defined in claim 2, wherein said region of increasing cross-section of said duct defines a sliver exit duct portion, said sliver exit duct portion being provided with a recess at the wall of said sliver funnel at the location of entry of the connection duct into said region of increasing cross-section.

4. The apparatus as defined in claim 2, wherein said region of increasing cross-section defines a sliver exit duct portion, said sliver exit duct portion being pro vided with a groove at the wall of said sliver funnel at the location of entry of said measuring duct into said region of increasing cross-section.

5. The apparatus as defined in claim 4, wherein said region of increasing cross-section is defined by tapered walls which enclose an angle a in the range of 6 to 16.

6. The apparatus as defined in claim 5, wherein the entry of said connection duct into said region of increasing cross-section forms an angle B with the sliver output direction which is in the range of30 to 7. The apparatus as defined in claim 2, wherein said region of increasing cross-section is defined by tapering walls which enclose an angle which does not exceed 25.

8. The apparatus as defined in claim 2, wherein entry of said duct into said region of increasing cross-section forms an angle B with the sliver throughput direction which does not exceed 9. The apparatus as defined in claim 2, wherein the entry of said connection duct into said region of increasing cross-section forms an angle fl -with the sliver output direction which does not exceed 90.

10. The apparatus as defined in claim 2, further including amplifier means operatively connected withsaid connection duct.

11. The apparatus as defined in claim 10, wherein said amplifier means is a fluid amplifier.

Claims

1. A method of detecting weight variations of a sliver on spinning preparatory machines, such as cards, draw frames and similar machines, at which the sliver passes through the duct of a sliver funnel, comprising the steps of: initially condensing the sliver in the duct of the sliver funnel in order to expel air entrained by the sliver, immediately thereafter expanding the condensed sliver in an expansion zone, generating in the expansion zone a pneumatic vacuum which is proportional to the weight variations of the throughpassing sliver, and utilizing the generated pneumatic vacuum for controlling an amplifier.

4. The apparatus as defined in claim 2, wherein said region of increasing cross-section defines a sliver exit duct portion, said sliver exit duct portion being provided with a groove at the wall of said sliver funnel at the location of entry of said measuring duct into said region of increasing cross-section.

5. The apparatus as defined in claim 4, wherein said region of increasing cross-section is defined by tapered walls which enclose an angle Alpha in the range of 6* to 16*.

6. The apparatus as defined in claim 5, wherein the entry of said connection duct into said region of increasing cross-section forms an angle Beta with the sliver output direction which is in the range of 30* to 85*.

7. The apparatus as defined in claim 2, wherein said region of increasing cross-section is defined by tapering walls which enclose an angle which does not exceed 25*.

8. The apparatus as defined in claim 2, wherein entry of said duct into said region of increasing cross-section forms an angle Beta with the sliver throughput direction which does not exceed 90*.

9. The apparatus as defined in claim 2, wherein the entry of said connection duct into said region of increasing cross-section forms an angle Beta with the sliver output direction which does not exceed 90*.

10. The apparatus as defined in claim 2, further including amplifier means operatively connected with said connection duct.