DK175987B1 - Former head with rotating drum - Google Patents

Description

DK 175987 B1 i

The present invention relates to a molding head of the type comprising at least one rotating drum mounted at each end in a bearing end and in which a needle roller is mounted and used for dry forming fibrous web, wherein a fiber material is mixed with air is supplied by blowing into said rotating drum.

5

Forming heads are known from the industry, where a mixture of fibers and air is injected into the ends of rotating perforated drums. Inside the drums is mounted a needle roller, which is also rotatable, which keeps the individual fibers floating so that no lumps occur. The forming head is positioned above an endless continuous forming wire 10 opposite a vacuum box, so that, by action from the vacuum, the fibers are sucked through the perforation in the drum and fixed to the underlying former wire.

In the known mold heads there are usually two drums, one rotating with the direction of the flow wire and the other against. Alternatively, there may be another 15 number of drums. The needle rollers provided with radially extending spikes are generally rotated against the direction of rotation of the respective drums.

So far, the drums have so far been mounted in bearing ends in a frame supporting the mold head as well as generally the vacuum box and mold wire. The needle rollers have been supported in bearing brackets located outside the ends of the drums.

Typically, mold heads have a width of approx. four meters. In such forming heads, it is normal for the needle rollers to be rotated at a speed of up to 1200-1400 rpm to achieve the desired capacity. The drums are usually rotated at a speed of approx. 200 rpm. Thus, requirements are set for the storage of both the drums and the needle rollers.

If a forming head is to have an active width of approx. four meters, the needle rollers cannot be rotated at the desired speed without the risk of intrinsic oscillations. This detracts from the quality of the dry product.

The perforation of the drums has a design which is determined from the fibers used in the preparation of the fibrous tissue. There is a need to change the drums so that perforations of appropriate shape are used to produce fibrous webs of various types of fibers and / or fiber blends. For example, paper products or diaper products are used primarily to produce cellulose fibers which may be blended with longer binder fibers.

5 When changing mold heads from one type of fiber / fiber blend to another type, it is necessary to replace the drums. So far, this replacement has been slow and laborious. To replace a drum, it has been necessary to remove the needle roller and pull it out of the end of the drum. Thus, there has been a need for a free space next to the mold head corresponding to the width of the mold head, the needle roll extending over the entire length of the drum and thus also the width of the mold head.

After removing the needle roller, the drum can be removed from its bearing brackets and removed, after which a new drum is mounted. The needle roller can then be reassembled in the new drum. The time course for such a replacement could take up to approx. 10 hours.

It is the object of the present invention to provide a forming head which is designed in a manner which allows for a simple replacement of the drums and where no substantial space is required next to the forming head in order to make the replacement and where at the same time it is possible to reduce the risk of intrinsic oscillations in the needle roller.

20

This is achieved according to the present invention with a molding head of the type mentioned in the introduction, which is characterized in that the drum is composed of at least two easily separable axial segments of cylindrical segments, each of which is mounted at each end on a bearing which is projecting from the bearing end and projecting into the drum, that the drum segments are bonded to the bearing ring of a corresponding segmented tension and that the needle roller is mounted at each end on a bearing bracket in the bearing end.

As the drum is made of segments, it is possible to leave the needle roller on its bearing brackets when replacing the drum. It is only necessary to open the tension ring and release the drum segments. These drum segments can be freely lifted in the space between the bearing ends. The additional drum segment (s) which is not lifted free and which is located on a downwardly facing side of the bearing ring is rotated upwards, after which these are also lifted free of the bearing ring. After removing the drum segments, it will be possible to place new drum segments as they are lifted into place on the bearing ring between the two bearing plates. When the drum segments are located on the bearing ring, the clamping ring is mounted again, after which the mold head is ready for operation.

5 Where it was possible to replace the drums with known forming heads, up to 10 hours, it is now possible to replace the drums of approx. 12 hours. Furthermore, there will be no need for free space next to the drum, as there is no need to pull the lateral levers laterally out of the drums before replacing the drum.

10 To release the drum, simply release the clamping ring. The clamping ring will typically be made of a number of segments corresponding to the number of drum segments and these segments will typically be provided with clamping faces or flanges where 1-2 screws are needed to clamp the clamping segments.

Thus, there will only be a need for loosening screws to release the clamping segments and thus the drum segments from the bearing ring which extends some distance at each end of the drum.

According to a particular embodiment, the molding head is characterized in that clamping segments, drum segments and bearing rings have means for releasably attaching the clamping segments and drum segments to the bearing rings. Such means may preferably be provided in the form of screws passing through holes in the tensioning and drum segments and which are screwed into the bearing rings.

Since the clamping segments and drum segments are retained on the bearing ring, all 25 clamping segments will be able to be separated from each other without the risk of downward friending drum segments and clamping segments. Thus, during disassembly and assembly, there will be no risk of damage to the drum segments during assembly and disassembly. According to a further embodiment, the molding head according to the invention is characterized in that the bearing ring has an outer diameter corresponding to the inner diameter of the drum, that on the outside of the bearing there is a protruding back and that the end parts of the drum segments are profiled to form a groove for receiving the back of the bearing. Alternatively, it is possible to profile the end portions of the drum segments so that they have an inner back and shape the bearing ring with a groove to accommodate such profiling. In this embodiment, it will be possible to avoid the risk of axial displacement of the drum relative to the bearing. At the same time, the interaction between the protruding back and the groove will serve to ensure a safe and correct positioning of the drum segment during assembly.

If the clamping segments are made with an internal groove arranged to receive the profiled end portions of the drum segments, an additional advantage is obtained by a fixed clamping with the end parts of the drum securely clamped between the inner ring located on the drum and the outside of the drum.

It is preferred to use a number of clamping segments corresponding to the number of drum segments. However, it will also be possible to use different numbers of clamping segments and drum segments.

If very large width molding heads are used, additional segment dividing tension rings may be located in one or more center positions between the ends of the drum. It is noted that such additional clamping rings will be located in mutually displaced positions over the length of the drum on subsequent drums. This makes it possible to achieve uniform deposition of fibers, although such additional tension rings are used. The need for additional clamping rings will depend on the width of the mold head / drum length as well as the dimensioning of the drum segments themselves.

By manufacturing the mold head with the bearing brackets for the needle rollers located within the bearing ends, it is possible to get a shorter length 'for the free part of the needle roller.

25

This is an advantage, since it makes it possible to rotate the needle rollers at a higher speed without the risk of being caused by intrinsic oscillation which can affect the distribution quality of the fibers. Self-oscillations in needle rollers occur when the rotational speed of the needle roll becomes too high or the length of the needle rolls becomes too large. An earlier solution 30 to this problem has been to manufacture the larger diameter needle rollers and drums, thereby making it possible to change the critical oscillation rpm. However, this known solution was unnecessarily space consuming and expensive. By placing the needle bracket bearing brackets as close to each other as possible, it becomes possible to rotate the needle rollers at higher rpm and thereby achieve a higher production capacity while providing a better quality of the distribution of the fibers in a forming head which has a large effective width of application.

It is possible that the needle bracket bearing brackets support the needle rollers at a distance from the S ends thereof. Hereby, a portion of the needle rollers may be in the bearing end or outside of these bearing ends in the connecting tubes connecting subsequent drums to each other to obtain a circulating flow of fibers through the drums.

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By using drums made of drum segments, it is possible to assemble a drum of segments having different perforations, thereby affecting the product characteristics. Thus, a variation in hole shape and size can be made. However, it will also be possible to assemble a drum of drum segments having the same perforation.

The invention will now be explained in more detail with reference to the accompanying drawing, in which fig. 1 is a side view of a mold head according to the invention; FIG. Figure 2 is a perspective exploded view of drums and needle rollers for a molding head according to the invention; 3 is an enlarged partial view illustrating a detail of FIG. 2, and FIG. 4 is a partial sectional view similar to FIG. Third

In the various figures, identical or similar elements will be designated by the same reference numeral and will therefore not be explained in detail in connection with each figure.

In FIG. 1 shows a molding head 1 according to the invention. The former head 1 is arranged over an endless former wire 2 which is advanced according to arrow 3, so that a fibrous web is formed on the upper side of the former wire 4. Below the former wire 2 in a position opposite the former head 1 a vacuum box 5 is arranged. which is connected via a line 6 to a vacuum source (not shown). The forming wire is passed around guide rollers 7. The formed fibrous web 4 is removed from the forming wire by means of transfer units well known in the art.

6 DK 175987 B1

Fiber material mixed with air is supplied to the mold head 1 via a pipe 8 for blow-in at the end of one of two drums 9, 10 provided in the mold head. The feed tube 8 is connected to tearing means in the form of hammer mills or other equipment which lists the fiber material to form individual fibers or individual fibers containing few agglomerates. The forming head comprises two rotating drums 9, 10, each containing a needle roller indicated at 11, 12. The fibers introduced into the drum 8 are circulated through the two drums 9,10, both of which are connected to transfer tubes 13 well known in this type of mold head.

FIG. 2 shows an exploded view of certain parts of the mold head 1. It is seen that the drums 9, 10 are made of two semi-cylindrical segments 9A, 9B, 10A, 10B. The drums 9, 10 are mounted on bearing rings 14 (only one is visible) projecting from bearing end 15, 16 at each end of the drums 9, 10. The needle rolls 11, 12 are mounted at each end on a bearing bracket 17 (only one is visible) located in or immediately on the bed end 15, 16. The drum segments 9A, 9B, 10A, 10B are held on the bearing rings 14 using tensioning segments 18 which are also provided as semi-circular tensioning segments. Each of the clamping segments has a hole 19 that can be aligned with a hole 20 in the associated drum segment for receiving a screw used to hold the drum segments and clamping segments 20 on the bearing ring 14.

FIG. 3 is an enlarged view illustrating the clamping of the drum segment 9B and clamping segments 18 on the bearing ring 14.

It will be seen that the bearing ring 14 has a protruding back 21 and that the end portion of the drum segment is profiled to form a groove 22 for receiving the back 21. It is further seen that the clamping segment 18 is profiled with a groove 23 which serves to receive the protruding back 21 with the drum segment 9B's profiling 22 located therebetween. The tensioning segments are provided with holes 24 for receiving screws for tightening the tensioning rings.

In FIG. 3, two holes 24 are shown in a clamping surface, which are threaded holes for receiving screws which are placed in through holes (not shown) in the cooperating clamping segment. With this design, screws 7 DK 175987 B1 can be used so that no protruding parts appear on the cylindrical clamping ring. Alternatively, it is possible to provide flanges with screw holes for clamping the clamping segments 18.

It is seen that the tension rings formed will clamp the drum about the bearing ring 14 for rotation with the latter. The bearing ring 14 will, in a manner known per se, be mounted in the bearing end 14 to be driven in rotation at the desired speed of rotation.

FIG. 2 shows that the needle rollers have a groove 25 in which they rest on the bearing bracket 17. The bearing-10 bracket 17 is mounted on the side plate of the bearing end 16. A bearing bracket is also provided for the other end of the needle roller and drive means for these, operated at a desired speed.

FIG. 4 shows a sectional view through the bearing ring at a position next to the joint of the tensioning segments and the drum segments, as illustrated in FIG. 3. It can be seen that the bearing ring 14 places into the bearing end 15 where it is mounted.

The above figures illustrate an embodiment of the invention, but other embodiments are possible if they only apply the basic idea of the invention with segment splitting 20 of the drums 9,10.

Thus, additional tension rings may be located at one or more locations over the length of the drums. It is also noted that the drums may be made with a different perforation than the circular apertures shown. Thus, any shape and size may be possible for drum perforation. ;

Furthermore, it will be possible to produce the bearing end members as an integral part of a machine frame and / or as an integral part of the vacuum box 5. Furthermore, it is possible to make the bearing end members pressure-proof and connect them to a pressure source via a stud 26, 30 so that an overpressure is maintained in the bearing ends.

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Claims (9)

A molding head of the kind comprising at least one rotating drum mounted at each end in a bearing end and in which a needle roller is mounted, which is used for dry forming fibrous web, where a fiber material mixed with air is supplied by blowing into said rotating drum, characterized in that the drum is composed of at least two easily separable axially-segmented segments, each of which at each end thereof is mounted on a bearing projecting from the bearing end and projecting into the the drum, that the drum segments are held together on the bearing ring by a corresponding segmental clamp and that the needle roller is mounted at each end on a bearing bracket in the bearing end. Forming head according to claim 1, characterized in that clamping segments, drum segments and bearings have means for releasably attaching the clamping segments and drum segments to the bearing rings. Molding head according to claim 2, characterized in that the means for releasable retaining comprises a screw which passes through holes in the tensioning segments and the drum segments and which is screwed into the bearing ring. 20 Molding head according to claim 1, characterized in that the bearing ring has an outer diameter corresponding to the inner diameter of the drum, that there is a protruding back on the outside of the bearing and that the end parts of the drum segments are profiled to form a groove for receiving the back of the bearing. 25 Molding head according to claim 4, characterized in that the tensioning segments have an inner groove for receiving the profiled end parts of the drum segments. An auger head according to any one of the preceding claims, characterized in that at one or more center positions between the ends of the drum additional tensioning rings are placed and such additional tensioning rings are mutually displaced on any subsequent drums. DK 175987 B1 9 Molding head according to any one of the preceding claims, characterized in that the bearing brackets for the needle roller are located within the bearing ends. Forming head according to claim 8, characterized in that the bearing brackets * 5 of the needle rollers support the needle rollers at a distance from the ends thereof. « 8 DK 175987 B1 Molding head according to any one of the preceding claims, characterized in that the drum segments composed to form a drum have the same or different perforation.