CN106400217B

CN106400217B - Drafting device for spinning frame

Info

Publication number: CN106400217B
Application number: CN201610592045.1A
Authority: CN
Inventors: 槌田大辅; 佐藤江平
Original assignee: Toyota Industries Corp
Current assignee: Toyota Industries Corp
Priority date: 2015-07-29
Filing date: 2016-07-25
Publication date: 2020-10-16
Anticipated expiration: 2036-07-25
Also published as: EP3124658B1; JP6358187B2; EP3124658A1; CN106400217A; TR201906637T4; JP2017031512A; ES2718243T3

Abstract

The invention discloses a drafting device which comprises a pressing part, wherein the pressing part increases the contact pressure between a rear bottom band ring and a rear top band ring without changing the contact pressure between a middle bottom band ring and a middle top band ring. This does not hinder the feeding of the fibers of the first roving, which are held by the front bottom and top rollers. Further, the separation of the fibers from the second roving and the breakage of the second roving between the holding positions of the front bottom roller and the front top roller and the holding positions of the rear bottom roller and the rear top roller can be restricted.

Description

Drafting device for spinning frame

Technical Field

The invention relates to a drafting device for a spinning frame, which can spin yarn strands and change the combination ratio of a first roving and a second roving.

Background

A drafting device of this type is disclosed, for example, in international publication No. wo 2015/033811. As shown in fig. 16 and 17, the draft device 100 includes a front roller 101, a middle band pair 102, and a rear band pair 103. The middle band pair 102 and the rear band pair 103 are located behind the front roller 101. Each middle loop pair 102 feeds a first roving S11 to the front roller 101. Each rear pair of turns 103 feeds a second roving S12 to the front roller 101. The two band pairs are arranged in two rows behind the front roller 101.

The front rollers 101 include a front bottom roller 101a and a front top roller 101 b. Each mid-band loop pair 102 includes a mid-bottom band loop 104 and a mid-top band loop 105. The mid-bottom band 104 extends around a tensioner rod 106, a mid-bottom roller 107, and a tensioner 108. The mid-top belt loop 105 extends around a mid-top roller 109 and a tensioner 111 of a loop cradle 110.

Each rear band pair 103 includes a rear bottom band 112 and a rear top band 113. The rear bottom strap extends around the tensioner rod 106, the rear bottom roller 114, and the tensioner 108. A rear bottom band 112, which rear bottom band 112 shares tensioner rod 106 and tensioner 108 with mid-bottom band 104, extends around rear bottom roller 114 around the outer periphery of mid-bottom roller 107.

The rear top band 113 extends around the rear top roller 115 and the tensioner 111 of the band cradle 110. A rear top band 113, which rear top band 113 shares the tensioner 111 with the middle top band 105, extends around the rear top roller 115 around the outer circumference of the middle top roller 109.

The first roving S11 is fed to the middle belt loop pair 102 and then drafted into a fiber between the front roller 101 and the middle belt loop pair 102. The second roving S12 is fed to the rear pair of bands 103 and then drafted into a fibrous form between the front roller 101 and the rear pair of bands 103. The fibers are discharged from the nose roller 101 and then twisted into a yarn strand.

The second roving S12 fed to the rear pair of belt loops 103 is formed of fibers. Some of the fibers are not held by any rollers between the position where the fibers are held by the front bottom roller 101a and the front top roller 101b and the position where the fibers are held by the rear bottom roller 114 and the rear top roller 115. Some of these fibers are entangled with: the fibers are held by the front bottom roller 101a and the front top roller 101b and are pulled by the fibers held by the front bottom roller 101a and the front top roller 101 b. This may cause the fibers to separate from the second roving S12 between the holding positions of the front bottom roller 101a and the front top roller 101b and the holding positions of the rear bottom roller 114 and the rear top roller 115 and cause the second roving S12 to break between the holding positions of the front bottom roller 101a and the front top roller 101b and the holding positions of the rear bottom roller 114 and the rear top roller 115.

In this regard, the contact pressure between the rear bottom band 112 and the rear top band 113 may be increased by reducing the clearance between the tensioner rod 106 and the tensioner 111 of the band cradle 110. This restricts the separation of the fibers from the second roving S12 between the holding positions of the front bottom roller 101a and the front top roller 101b and the holding positions of the rear bottom roller 114 and the rear top roller 115 and the breakage of the second roving S12 between the holding positions of the front bottom roller 101a and the front top roller 101b and the holding positions of the rear bottom roller 114 and the rear top roller 115.

However, when the gap between the tensioner rod 106 and the tensioner 111 of the looped cradle 110 is reduced, the contact pressure between the mid-bottom strap 104 and the mid-top strap 105 is also increased. This hinders the feeding of the fibers forming the first roving S11, which is fed to the middle band pair 102, and which are held by the front bottom roller 101a and the front top roller 101 b. Thus, the draft of the first roving S11 is hindered between the front roller 101 and the middle belt loop pair 102.

Disclosure of Invention

An object of the present invention is to provide a drafting device for a spinning frame which limits breakage of a second roving fed to a rear apron pair while facilitating drafting of a first roving fed to an intermediate apron pair.

In order to solve the above problems, a first aspect of the present invention provides a drafting device for a spinning frame, which spins a yarn strand while changing a combination ratio of a first roving and a second roving. The draft device comprises: a front roller comprising a front bottom roller and a front top roller; the middle roller comprises a middle bottom roller and a middle top roller; a back roller comprising a back bottom roller and a back top roller; a pair of mid-belt loops feeding the first roving to the front roller; and a pair of rear bands that feed the second roving to the front roller. The mid-band pair includes a mid-bottom band extending around the mid-bottom roller and a mid-top band extending around the mid-top roller. The middle top band is driven by the middle bottom roller while being pressed by the middle bottom band. The pair of back bands includes a back bottom band extending around the back bottom roller and a back top band extending around the back top roller. The rear top band is driven by the rear bottom roller while being pressed by the rear bottom band. The draft device includes a contact pressure adjusting portion that increases a contact pressure between the rear bottom band and the rear top band in at least a part of the rear band pair without changing a contact pressure between the middle bottom band and the middle top band.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

Drawings

The invention, together with its objects and advantages, may best be understood by making reference to the following description of the presently preferred embodiment taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic perspective view showing one embodiment of a drafting device according to the present invention;

FIG. 2 is a schematic cross-sectional view of a drawing device;

FIG. 3 is a schematic perspective view of an intermediate trumpet member;

FIG. 4 is a cross-sectional view of the intermediate trumpet member;

fig. 5A is an exploded perspective view showing a modified example of the intermediate trumpet member and the pressing member;

FIG. 5B is a schematic perspective view of the intermediate trumpet member;

FIG. 6 is a cross-sectional view of the intermediate trumpet member;

fig. 7 is a schematic perspective view showing a modified example of the tensioner lever;

FIG. 8 is a side view of the tensioner rod;

fig. 9 is a schematic perspective view showing a modified example of the tensioner lever;

fig. 10 is a schematic perspective view showing a modified example of the middle top roller;

fig. 11A is a schematic view showing a state when the pressing member is not coupled to the middle top roller;

fig. 11B is a schematic view showing a state when the pressing member is coupled to the middle top roller;

fig. 12 is a schematic perspective view showing a part of a modified example of the draft device;

fig. 13 is a sectional view showing a modified example of the intermediate trumpet member;

fig. 14 is a sectional view showing a modified example of the intermediate trumpet member;

fig. 15A and 15B are sectional views showing modified examples of the intermediate trumpet member;

fig. 16 is a schematic perspective view of a drafting device of the prior art; and

fig. 17 is a schematic cross-sectional view of a drafting device of the prior art.

Detailed Description

An embodiment of a drafting device for a spinning frame will now be described with reference to fig. 1 to 4.

Referring to fig. 1 and 2, the draft device 10 includes a front roller 11, a middle roller 12 located behind the front roller 11, and a rear roller 13 located behind the middle roller 12. The drawing device 10 has a three-roll configuration. The front rollers 11 include a front bottom roller 11a and a front top roller 11 b. Each of the middle rollers 12 includes a middle bottom roller 12a and a middle top roller 12 b. Each rear roller 13 includes a rear bottom roller 13a and a rear top roller 13 b. The drafting device 10 comprises a middle pair of turns 14 and a rear pair of turns 15, wherein the middle pair of turns 14 feeds the first roving S1 to the front roller 11 and the rear pair of turns 15 feeds the second roving S2 to the front roller 11. The drafting device 10 comprises pairs of turns in two rows, so that both types of roving are fed to a common front roller 11.

The front bottom roller 11a is supported by a roller support (not shown). The front top roller 11b is supported by a support arm 17 and a weight arm 16, and the weight arm 16 is located above the middle top roller 12b and the rear top roller 13 b. The drafting device 10 is of the double spindle integrated type and comprises top rollers such as front top rollers 11b located at opposite sides of a counterweight arm 16.

Each middle strap pair 14 includes a middle bottom strap 14a and a middle top strap 14 b. The mid-bottom strap 14a extends around the mid-bottom roller 12a, tensioner rod 20 and tensioner 21. The tensioner lever 20 and the tensioner 21 are located between the front roller 11 and the middle roller 12. The middle top band 14b extends around the middle top roller 12b and a band cradle 22, the band cradle 22 being located between the front roller 11 and the middle roller 12. The middle-top band 14b is driven by the middle-bottom roller 12a while being pressed by the middle-bottom band 14 a.

Each rear band pair 15 comprises a rear bottom band 15a and a rear top band 15 b. The rear bottom strap 15a extends around the rear bottom roller 13a, tensioner rod 20 and tensioner 21. Thus, both the mid-bottom band 14a and the rear bottom band 15a extend around the tensioner rod 20 and the tensioner 21. The rear bottom band 15a extends around the rear bottom roller 13a around the outer peripheral portion of the middle bottom roller 12 a.

The rear top band 15b extends around the rear top roller 13b and the band cradle 22. Thus, both the mid-top 14b and rear top 15b straps extend around the strap cradle 22. The back top band 15b extends around the back top roller 13b around the outer peripheral portion of the middle top roller 12 b. The rear top band 15b is driven by the rear bottom roller 13a while being pressed by the rear bottom band 15 a.

The first support bar 18 extends along the middle roller 12 and the rear roller 13 between the middle roller 12 and the rear roller 13. The intermediate trumpet member 30 is coupled to the first support rod 18. Thus, the intermediate trumpet member 30 is located between the middle roller 12 and the rear roller 13. Further, a second support bar 19 is positioned behind the rear roller 13. The rear horn 19a is coupled to the second support rod 19. Each rear horn 19a guides the second roving S2 to the corresponding rear pair of loops 15.

As shown in fig. 3, the intermediate horn member 30 includes a coupling portion 31 of a rectangular shape. The coupling portion 31 includes a rear surface 31a, and the rear surface 31a is in contact with the first support rod 18. When the longitudinal direction of the coupling portion 31 coincides with the longitudinal direction of the first support rod 18, the coupling portion 31 is coupled to the first support rod 18.

The coupling portion 31 includes an upper edge formed integrally with a square-tube-shaped intermediate flared portion 32. The middle horn 32 directs the first roving S1 to the corresponding mid-belt loop pair 14. The intermediate flared portion 32 is located on a first end of the coupling portion 31. The middle horn 32 includes a feed port 32a to which the first roving S1 is fed and a discharge port 32b that discharges the first roving S1. The feed port 32a and the discharge port 32b are opened in directions orthogonal to each other.

Further, the upper edge of the coupling portion 31 is formed integrally with a plate-like rear band pair guide 33, which plate-like rear band pair guide 33 guides the rear band pair 15. Thus, the intermediate horn member 30 includes an intermediate horn 32 and a rear band pair guide 33. The rear band pair guide 33 is located on the second end of the coupling portion 31. The rear band pair guide 33 includes a flat guide surface 33a opposite the intermediate flare 32. The rear pair of belt loops 15 are arranged between the intermediate flared portion 32 and the guide surface 33a of the rear pair of belt loops guide 33 while being guided by the guide surface 33 a.

As shown in fig. 4, the first support rod 18 is provided with an internally threaded hole 18 a. The coupling portion 31 is provided with a screw insertion hole 31 h. When the screw 35 is inserted through the screw insertion hole 31h and fitted into the internal threaded hole 18a, the coupling portion 31 is coupled to the first support rod 18.

The upper edge of the coupling portion 31 includes a portion between the intermediate flared portion 32 and the rear band pair guide 33 that defines the pressing portion 31 f. The pressing portion 31f presses the rear bottom band 15a to the rear top band 15 b. As indicated by an arrow X1 in fig. 4, the pressing portion 31f is inclined toward the following direction: the direction is a direction in which the pair of rear straps 15 travel with respect to the lateral direction of the coupling portion 31. The pressing portion 31f locally increases the contact pressure between the rear bottom band 15a and the rear top band 15b by pressing the rear bottom band 15a and the rear top band 15 b. However, the contact pressure between the mid-bottom band 14a and the mid-top band 14b does not change. Thus, the pressing portion 31f serves to increase the contact pressure between the rear bottom band 15a and the rear top band 15b in at least a part of the rear band pair 15 without changing the contact pressure between the middle bottom band 14a and the middle top band 14 b. A pressing part 31f, which pressing part 31f serves as a contact pressure adjusting part, is located between the middle roller 12 and the rear roller 13.

Referring to fig. 1, a first roving S1 is fed from a first roving winding, suspended from a creel (not shown), through the intermediate horn 32 and to the midband pair 14. Further, a second roving S2 is fed from a second roving winding, suspended from a creel (not shown), through the rear horn 19a and to the rear band pair 15.

The first roving S1 is fed to the middle belt loop pair 14 and drafted into a fiber (fleece) between the front roller 11 and the middle belt loop pair 14. Subsequently, the fiber formed of the first roving S1 is guided to a yarn guide (not shown) and a yarn guide (not shown) (tractor) and wound around a bobbin. The second roving S2 is fed to the rear pair of bands 15 and drafted into a fibrous form between the front roller 11 and the rear pair of bands 15. Subsequently, the fibrous object formed of the second roving S2 is guided to a guide hook (not shown) and wound around a bobbin.

When the first roving S1 and the second roving S2 are fed simultaneously, the three bottom rollers, i.e., the front bottom roller 11a, the middle bottom roller 12a, and the rear bottom roller 13a are all driven. The first roving S1 is fed from the intermediate horn 32 and drafted into a first fiber between the front roller 11 and the middle belt loop pair 14. The second roving S2 is fed from the rear horn 19a and drafted into a second fibrous material between the front roller 11 and the rear band pair 15. The first and second fibers are fed from the front roller 11 and then twisted into a yarn strand.

The spinning conditions may be changed from a state in which the first roving S1 and the second roving S2 are simultaneously fed to a state in which only one of the first roving S1 and the second roving S2 is fed. In such a case, when the feeding of the roving is stopped, the pair of bands corresponding to the roving is deactivated. For example, when the feed of the first roving S1 is stopped, the bottom roller 12a is deactivated. Deactivation of the mid-bottom roller 12a deactivates the mid-bottom band 14 a. At the same time, the middle top band 14b is also deactivated. This deactivates the mid-band pair 14. When the middle band pair 14 is deactivated, the first roving S1 is broken between the middle band pair 14 and the front roller 11 during spinning. When the feeding of the first roving S1 is started again, the bottom roller 12a is activated. This causes the center band pair 14 to actuate. Thus, the first roving S1 is smoothly drafted between the front roller 11 and the middle belt loop pair 14.

When the feeding of the second roving S2 is stopped, the rear bottom roller 13a is deactivated. Deactivation of the rear bottom roller 13a deactivates the rear bottom band 15 a. At the same time, the rear top band 15b is deactivated. This deactivates the rear pair of straps 15. When the rear band pair 15 is deactivated, the second roving S2 is broken between the rear band pair 15 and the front roller 11 during spinning. When the feeding of the second roving S2 is started again, the rear bottom roller 13a is started. This activates the rear band pair 15. Thus, the second roving S2 is smoothly drafted between the front roller 11 and the rear band pair 15.

During spinning, the combination ratio of the first roving S1 and the second roving S2 is changed by controlling activation and deactivation of the center band pair 14 and the rear band pair 15, wherein the first roving S1 and the second roving S2 form two types of rovings. This continuously spins the target yarn strand.

In one example, when spinning a slub yarn, the activation and deactivation of the middle band pair 14 and the rear band pair 15 is controlled such that one of the first roving S1 and the second roving S2 is continuously fed while the other roving is intermittently fed. In one example, when the first roving S1 and the second roving S2 have different colors, the activation and deactivation of the middle band pair 14 and the rear band pair 15 is controlled such that the first roving S1 and the second roving S2 are alternately fed. This spun the following yarns: in this yarn, portions having different colors are successively alternated. Slub yarns can be set to have any thickness, any length, any spacing, and any color combination ratio. When the middle bottom roller 12a and the rear bottom roller 13a are activated according to the above setting, a desired yarn can be spun.

The operation of the present embodiment will now be described.

Some of the fibers forming the second roving S2, which is fed to the rear band pair 15, are not held by any roller between the holding positions of the front bottom roller 11a and the front top roller 11b and the holding positions of the rear bottom roller 13a and the rear top roller 13 b. Some of such fibers are entangled with: the fibers are held by the front bottom roller 11a and the front top roller 11b and are pulled by the fibers held by the front bottom roller 11a and the front top roller 11 b. This may cause the fibers to separate from the second rovings S2 between the holding positions of the front bottom roller 11a and the front top roller 11b and the holding positions of the rear bottom roller 13a and the rear top roller 13b and cause the second rovings S2 to break between the holding positions of the front bottom roller 11a and the front top roller 11b and the holding positions of the rear bottom roller 13a and the rear top roller 13 b.

In this regard, in the present embodiment, the pressing portion 31f increases the contact pressure between the rear bottom band 15a and the rear top band 15b in at least a part of the rear band pair 15 by pressing the rear bottom band 15a to the rear top band 15 b. This restricts the separation of the fibers from the second roving S2 between the holding positions of the front bottom roller 11a and the front top roller 11b and the holding positions of the rear bottom roller 13a and the rear top roller 13b and the breakage of the second roving S2 between the holding positions of the front bottom roller 11a and the front top roller 11b and the holding positions of the rear bottom roller 13a and the rear top roller 13 b.

This embodiment mode has advantages described below.

(1) The draft device 10 includes a pressing portion 31 f. Each pressing portion 31f functions as a contact pressure regulating portion that increases the contact pressure between the rear bottom band 15a and the rear top band 15b in at least a part of the rear band pair 15 without changing the contact pressure between the middle bottom band 14a and the middle top band 14 b. In this configuration, the contact pressure between the mid-sole band 14a and the mid-top band 14b will not increase in accordance with the contact pressure between the rear-sole band 15a and the rear-top band 15 b. Thus, the contact pressure between the mid-bottom band 14a and the mid-top band 14b does not increase. This does not hinder the feeding of the fibers of the first roving S1 held by the front bottom roller 11a and the front top roller 11 b. Further, as compared with the configuration not including the pressing part 31f, the separation of the fibers from the second rovings S2 and the breakage of the second rovings S2 between the holding positions of the front bottom roller 11a and the front top roller 11b and the holding positions of the rear bottom roller 13a and the rear top roller 13b are restricted. Accordingly, breakage of the second roving S2, which is fed to the rear band pair 15, is controlled while facilitating drafting of the first roving S1, which is fed to the middle band pair 14, S1.

(2) The presser part 31f is located between the middle roller 12 and the rear roller 13. Thus, the pressing portion 31f increases the position of the contact pressure between the rear bottom band 15a and the rear top band 15b as compared to when the pressing portion 31f is located between the front roller 11 and the middle roller 12, and separates from the front roller 11. This prevents the following situations: in this case, the feeding of the second roving S2 held by the front bottom roller 11a and the front top roller 11b is hindered due to the contact pressure between the rear bottom band 15a and the rear top band 15b increased by the pressing part 31 f.

(3) The pressing portion 31f is disposed on the intermediate horn member 30. The intermediate horn member 30 is located between the middle roller 12 and the rear roller 13. Thus, the supporting member for arranging the pressing portion 31f on the intermediate horn member 30 does not need to be separately arranged between the middle roller 12 and the rear roller 13. This simplifies the overall structure of the device.

(4) When the pressing portion 31f and the intermediate horn member 30 are separate members, a task for coupling the pressing portion 31f to the intermediate horn member 30 is necessary. In this regard, in the present embodiment, the pressing portion 31f is formed integrally with the intermediate horn member 30. This configuration eliminates the need for the task of coupling the pressing portion 31f to the intermediate horn member 30. Thus, coupling efficiency is improved. Furthermore, the number of components is reduced.

(5) The pressing portion 31f is inclined toward the traveling direction of the rear band pair 15 with respect to the lateral direction of the coupling portion 31. This allows the rear band pair 15 to travel smoothly, compared to when the pressing portion 31f is inclined toward the side opposite to the traveling direction of the rear band pair 15 with respect to the lateral direction of the coupling portion 31.

It will be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the scope of the invention. In particular, it should be understood that the present invention may be embodied in the following forms.

As shown in fig. 5A and 5B, the pressing member 41 including the pressing portion 41f can be separated from the intermediate horn member 30. The pressing member 41 is a rectangular plate. When the longitudinal direction of the pressing member 41 coincides with the lateral direction of the coupling portion 31, the pressing member 41 is positioned between the intermediate flared portion 32 and the rear band pair guide 33. The pressing member 41 is provided with an elliptical hole defining a screw insertion hole 41 h. The screw insertion hole 41h extends in the longitudinal direction of the pressing member 41. When the screw 35 is inserted through the screw insertion hole 41h and the screw insertion hole 31h and fitted into the internal threaded hole 18a, the pressing member 41 and the coupling portion 31 are coupled to the first support bar 18.

As shown in fig. 6, the pressing member 41 includes an upper end that protrudes upward beyond a portion of the upper edge of the coupling portion 31 between the intermediate horn 32 and the rear band pair guide 33. Further, the upper end of the pressing member 41 defines a pressing portion 41f that presses the rear bottom band 15a to the rear top band 15 b. When the pressing portion 41f presses the rear bottom band 15a to the rear top band 15b, the contact pressure between the rear bottom band 15a and the rear top band 15b is increased in at least a part of the rear band pair 15 without changing the contact pressure between the middle bottom band 14a and the middle top band 14 b.

In the above configuration, the pressing member 41 is removably attached to the intermediate horn member 30. Thus, the contact pressure between the rear bottom band 15a and the rear top band 15b can be adjusted. This further restricts breakage of the second roving S2, which is fed to the rear pair of belt loops 15, S2. Further, the screw insertion hole 41h is an elliptical hole. Thus, the amount of projection of the pressing member from the upper edge of the coupling portion 31 can be adjusted by adjusting the position of the screw 35 relative to the screw insertion hole 41 h. Therefore, the contact pressure between the rear bottom band 15a and the rear top band 15B can be easily adjusted.

As shown in fig. 7 and 8, tensioner rod 20, about which tensioner rod 20 both mid-bottom band 14a and rear bottom band 15a extend, may include a pressing portion 51 f. The press 51f is located on the surface of the bottom strap 15a of the tensioner rod 20 after deployment. The surface of the bottom band 15a after the tensioner rod 20 is deployed, i.e., the pressing portion 51f, is located above the surface of the bottom band 14a during the deployment of the tensioner rod 20. In this case, the rear bottom band 15a is laid at a position close to the rear top band 15b, compared to when the pressing part 51f and the surface of the bottom band 14a are at the same height in the laying of the tensioner lever 20. Thus, the rear bottom band 15a is pressed to the rear top band 15b by the pressing portion 51 f. In this configuration, the tensioner lever 20, which tensioner lever 20 is a conventional member located between the front roller 11 and the middle roller 12, includes the pressing portion 51 f. Thus, a member supporting the pressing part 51f need not be separately arranged between the front roller 11 and the middle roller 12. This simplifies the overall structure of the device.

As shown in fig. 9, a pressing member 61 including a pressing portion 61f may be coupled to the tensioner rod 20. More specifically, the pressing portion 61f and the tensioner lever 20 may be separate members.

As shown in fig. 10, the pressing member 71 may be located on a circumferential surface of each of the middle top rollers 12b at a position overlapping with the back top band 15 b. A pressing member 71 having a tubular shape is coupled to a circumferential surface of the middle top roller 12b and is rotatably supported by the middle top roller 12 b. The pressing member 71 increases the contact pressure between the rear bottom band 15a and the rear top band 15b without allowing the rear bottom band 15a to contact the middle bottom roller 12 a. The portion of the middle top roller 12b overlapping the rear top band 15b has a smaller outer diameter than the portion of the middle top roller 12b overlapping the middle top band 14 b. The pressing member 71 has a smaller outer diameter than the portion of the middle top roller 12b that overlaps the middle top band 14 b.

As shown in fig. 11A, when the pressing member 71 is not coupled to the middle top roller 12b, the rear top band 15b is not in contact with the middle top roller 12 b. Further, the rear bottom band 15a does not contact the middle bottom roller 12 a. As shown in fig. 11B, when the pressing member 71 is coupled to the middle top roller 12B, the pressing member 71 is in contact with the rear top band 15B and the pressing member 71 presses the rear top band 15B to the rear bottom band 15 a. This increases the contact pressure between the rear bottom band 15a and the rear top band 15b in at least a part of the rear band pair 15. Even in this state, the rear bottom band 15a is not in contact with the middle bottom roller 12 a. Further, the pressing member 71 rotates relative to the middle top roller 12 b. This reduces friction between the pressing member 71 and the rear top band 15 b. The pressing member 71, which pressing member 71 serves as a contact pressure adjusting portion, may be disposed on the middle top roller 12b, which middle top roller 12b is a conventional member. The pressing member 71 may be arranged on the middle top roller 12b such that the pressing member 71 rotates integrally with the middle top roller 12b instead of rotating with respect to the middle top roller 12 b.

As shown in fig. 12, the pressing member 81 may be located between each of the middle top rollers 12b and the corresponding rear top roller 13 b. The pressing member 81 includes a pressing portion 81f that presses the rear top band 15b to the rear bottom band 15 a. The pressing member 81 includes a pressing portion 81f and a supporting portion 81a, the supporting portion 81a being formed continuously with the pressing portion 81f and supported by the middle-top roller 12 b. The pressing portion 81f and the supporting portion 81a are rod-shaped. The bearing portion 81a can pivot about the rotational axis of the middle top roller 12 b. When the bearing portion 81a pivots toward the rear bottom band 15a about the rotational axis of the middle top roller 12b, the pressing portion 81f presses the rear top band 15b to the rear bottom band 15 a. This increases the contact pressure between the rear bottom band 15a and the rear top band 15b in at least a part of the rear band pair 15.

As shown in fig. 13, the upper end of the pressing member 41 may include a rotating member 41 a. The rotating member 41a may rotate while contacting the rear bottom band 15 a. The rotating member 41a presses the rear bottom band 15a to the rear top band 15 b. Thus, the rotating member 41a functions as a contact pressure adjusting portion that increases the contact pressure between the back bottom band 15a and the back top band 15b in at least a part of the back band pair 15. In this case, the rotating member 41a rotates while contacting the rear bottom band 15 a. This allows the rear bottom band pair 15a to travel smoothly.

As shown in fig. 14, in the embodiment shown in fig. 13, the rotating member 41b may be positioned opposite to the rotating member 41 a. The rotating member 41b is supported by the weight arm 16 so that the rotating member 41b can rotate while contacting the rear top band 15 b. The rotating member 41b presses the rear top band 15b to the rear bottom band 15 a. Thus, the rear band pair 15 is held between the two

rotary members

41a, 41 b. This increases the contact pressure between the rear bottom band 15a and the rear top band 15 b. The two

rotating members

41a, 41b function as contact pressure adjusting portions that increase the contact pressure between the rear bottom band 15a and the rear top band 15b in at least a part of the rear band pair 15. This restricts the bending of the travel path of the rear band pair 15 and allows the rear band pair 15 to travel smoothly.

As shown in fig. 15A, the pressing portion 31f may extend in the lateral direction of the coupling portion 31. Further, as shown in fig. 15B, the pressing portion 31f may be inclined toward the side opposite to the traveling direction of the rear band pair 15 with respect to the lateral direction of the coupling portion 31.

The intermediate horn member 30 does not necessarily have to include the intermediate horn 32 and the rear band pair guide 33. The intermediate horn member 30 need only include the intermediate horn 32. Thus, the intermediate trumpet member 30 only needs to guide at least the first roving S1 to the center loop pair 14.

The drafting device is not limited to a three-roll configuration and may have a four-roll configuration. For example, a second rear roller may be arranged behind the rear pair of belt loops 15. Then, the first roving S1 and the second roving S2 may be drafted between the middle band pair 14 and the second rear roller and between the rear band pair 15 and the second rear roller. In a four roll configuration, instead of roving, a sliver (sliver) may be fed to the drafting device 10 to spin the yarn.

The spinning frame may be a roving frame.

The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

1. A draft device for a spinning frame, which spins a yarn strand while changing a combination ratio of a first roving and a second roving, wherein the draft device comprises: a front roller comprising a front bottom roller and a front top roller; the middle roller comprises a middle bottom roller and a middle top roller; a back roller comprising a back bottom roller and a back top roller; a pair of mid-belt loops feeding the first roving to the front roller; and a pair of rear bands feeding the second roving to the front roller, wherein the pair of mid bands includes a mid-bottom band extending around the mid-bottom roller and a mid-top band extending around the mid-top roller, the mid-top band being driven by the mid-bottom roller while being pressed by the mid-bottom band, the pair of rear bands includes a rear bottom band extending around the rear-bottom roller and a rear top band extending around the rear-top roller, the rear top band being driven by the rear-bottom roller while being pressed by the rear bottom band, the draft device being characterized by further comprising:

a contact pressure adjustment portion that bends a travel path of the rear band pair in at least a portion of the rear band pair to increase a contact pressure between the rear bottom band and the rear top band without increasing a contact pressure between the middle bottom band and the middle top band, thereby causing no change in the contact pressure between the middle bottom band and the middle top band.

2. The draft device for spinning frame according to claim 1, wherein the contact pressure adjusting portion is located between the middle roller and the rear roller.

3. The drafting device for spinning frame as claimed in claim 2, further comprising an intermediate trumpet member located between the middle roller and the rear roller to guide the first roving to the middle band pair,

wherein the intermediate trumpet member includes the contact pressure adjusting portion.

4. The drafting device for spinning frame as claimed in claim 3, wherein the contact pressure regulating part is formed integrally with the intermediate trumpet member.

5. The drafting device for spinning frame as claimed in claim 3, wherein the contact pressure regulating portion and the intermediate trumpet member are separate members.

6. The drafting device for spinning frame as claimed in claim 1, further comprising a tensioner lever between said front roller and said middle roller, wherein,

the mid-bottom strap and the rear bottom strap both extend around the tensioner rod, and

the contact pressure adjusting part is positioned on the surface of the tensioner rod, which is provided with the rear bottom belt ring.

7. The drafting device for spinning frame as claimed in claim 1, wherein:

the back top band extends around the back top roller around the outer circumference of the middle top roller; and is

The contact pressure regulating portion is located on a circumferential surface of the middle top roller at a position overlapping with the back top band.