JPH08175727A - Web conveyor and web carrying roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a web carrying roller capable of carrying an extremely thin web at a great web speed with well tractive force. SOLUTION: A web carrying roller 18 has a peripheral face provided with a spirally extending groove 42 and a upheaved part 44, the upheaved part having protruded faces 46, 48. An extremely thin web 30 to be carried is moved rising on the upheaved part and falling in the groove across the width of the roller at the start end of winding angle α of the roller and is left apart from the protruded faces of the upheaved part, whereby air drawn between the web and the upheaved part can flow into the groove.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a device for carrying web material such as plastic sheets or paper of indefinite length. More specifically, the present invention includes a specially shaped roller for high speed transport of wide webs of extremely thin or very small thickness, such as less than 0.001 inch (0.0254 mm), It relates to such a device.

[0002]

2. Description of the Related Art FIG. 1 schematically shows an example of a large variety of manufacturing equipment for carrying and processing web materials. A supply 10, such as a storage roll, supplies a web 12 of indefinite length. In a known manner, the web is treated area 14
To the take-up roller 16 through a plurality of regular cylindrical drive and idler rollers 18, typically one having a width greater than the width of the web, only one of which is shown.
The rolls 10 and 16 are also driven. Some rollers 18 are driven by means such as a motor 20. These rollers and the other known web guide structure of the device (not shown) act as a means for guiding the web from 10 ° to 300 °.
Wrap on each roller over a wrap angle α that can be in the range of °. Various surface treatments, such as coating, printing, textured surface treatments, etc., are performed on the web in the treated area, but such surface treatments are often free of slippage between the web and the drive or idler rollers. Required. Sliding or pulling losses between the web and the rollers are undesirable as they cause problems for the web such as unrolling movements, electrostatic charging, scratch formation, wrinkle formation and the like. Sufficient frictional force is required between the web and each roller to eliminate such slippage, and this frictional force is commonly known as roller traction.

Roller traction is obtained at low web speeds by smooth surfaced rollers, but as the web speed increases to speeds of 100 feet per minute (30.5 meters per minute), it is shown by the arrows in FIG. As a result, air is typically drawn between the web and the rollers. This drawn air keeps at least a portion of the web out of contact with the rollers, causing slippage. In order to allow the entrained air to escape between the web and the roller, various types of surface modalities have been provided on the roller surface to allow adequate traction to be maintained at low and high web speeds.

FIG. 2 shows diagrammatically an axial cross-section of the web engaged with the above-described surface modality at the beginning of the wrap angle α. The outer surface of the roller 18 is provided with a plurality of circumferentially extending grooves 24 which may be individual annular grooves or one or more continuous spiral grooves. The grooves are separated by a ridge 26 which extends around the outer surface of which the outer surface is flat or straight when viewed axially. That is,
These ridges have a flat cross section when viewed in the direction of movement of the web through the device. For example, 6 to 60 grooves per inch (2.36 to 23.6 grooves per cm) are provided, the axial widths of these grooves are approximately the same, and each groove is 0.002 to 0.010. It has a depth in the range of inches (0.0508 to 0.254 mm).

0.002 to 0.0075 inches (0.
When a polyethylene terephthalate web having a thickness t in the range of 0508 to 0.191 mm) is carried using a 2.8 inch (71.1 mm) diameter roller of the type shown in FIG. 2 has sufficient rigidity, beam strength or bending resistance, and as shown in FIG.
At the beginning of the ridge 26 is sufficient to engage the flat cross-section surface of the ridge 26. Therefore, any air that moves with the web at the beginning of the wrap angle is forced into the groove 24 and good traction is maintained by the web-ridge engagement.

FIG. 3 shows that for relatively thick webs 0.
Coefficient of friction of 1,000 feet per minute between a 0025 inch (0.0635 mm) thick 54 inch (1372 mm) wide web and a grooved 2.8 inch (71.1 mm) roller It shows only a slight change over the range of web speeds (305 m / min). A slightly larger drop in the coefficient of friction results in 15 pounds or 0 per linear inch across the web compared to a tension of 25 pounds or 0.45 pounds per inch (11.34 kg per mm or 0.008 kg) in a straight line across the web. Observed for a web tension of .27 pounds (6.8 kg or 0.0048 kg per mm).

However, the web 12 is extremely thin, 0.0
For thickness less than 01 inch (0.025 mm),
Rollers of the type shown in FIG. 2 are unable to obtain adequate traction at web speeds above a few hundred feet per minute.
Traction is no longer held constant, but rather a function of web thickness and web speed. The inventor has discovered that such poor performance of grooved rollers results from a reduction in bending resistance of extremely thin webs. For thicker webs, the bending resistance allows the webs to straddle the grooves and engage the ridges of known grooved rollers in such a manner as to minimize radial deformation of the web as shown in FIG. Is enough for However, for very thin webs, the web is so thin that it bends into the groove at the beginning of the wrap angle and rises above the ridge as shown in FIG. A similar effect is observed in webs thicker than 0.001 inches (0.0254 mm) due to the web material and the ridge and groove geometry. The extremely thin web 30 is therefore laterally deformed into a series of relatively high ridges 32 and low valleys 34, which causes the web 30 to essentially rim or ridge 3 of each ridge.
Only 6 and 38 come into contact with the roller. As a result, the air volume 40 becomes somewhat trapped underneath the high ridge 32 because the contact between the web and the edges 36, 38 blocks or severely impedes air flow into the groove. . Due to the essentially linear contact between the webs at edges 36 and 38, the traction force is severely reduced, leading to the problems mentioned above.

FIG. 5 shows 0.00025 inch (0.006).
4 mm thick, 55 inch (1397 mm) wide, polyethylene terephthalate web running on 5.6 inch (142.2 mm) grooved rollers, the coefficient of friction between the web and the roller is 800 feet per minute. Minute 244
m) showing a rapid descent over the range of web velocities. A slightly larger drop in coefficient of friction is 10 pounds or 0.18 pounds per linear inch across the web (6.8 kg or 0.0048 kg per mm) tension or 25 pounds or 0.45 pounds per linear inch across the web. 10 lbs / 0.18 lbs / inch (4.5 kg / mm or 0.0032 k / mm) of straight line across the web compared to (11.34 kg / mm or 0.008 kg / mm) tension
Observed for web tension in g).

[0009]

Therefore, a roller capable of carrying very thin webs and other webs that deform into known grooved rollers with good traction under increased web speeds. Is required.

A primary object of the present invention is to provide an improved roller for transporting extremely thin webs at increased web speeds without substantial loss of traction or risk of damaging the webs.

[0011]

The above objectives are given by way of illustration only, and other desirable objectives and advantages inherently achieved by the disclosed invention will occur or become apparent to those skilled in the art. However, the scope of the invention is limited only by the claims.

The invention is defined by the claims. One embodiment of the device according to the invention is particularly suitable for transporting very thin webs having a width. A source of web to be transported, such as a storage roll, feeds the web over at least one cylindrical roller having an outer surface that is longer than the width of the web to be transported, a portion of the web. Is wound over an angle α. In particular, according to the invention, the roller comprises axially spaced grooves extending along a lengthwise direction on a plurality of circumferential surfaces formed on the outer surface,
Each groove has an axial width, and the roller comprises a plurality of ridges formed on the outer surface and extending between the grooves, each ridge having an axial width and a convexly curved central surface. However, this convex surface has a maximum radius from the center line of the roller. The ridges can be continuous. In order to best convey an extremely thin web, the curvature of the convex surface of the ridge and the axial width of the groove and the ridge are such that the web is above the ridge and in the groove at almost the beginning of the wrapping angle α during roller rotation. Selected to undulate along the width of the roller but away from the convex surface of the ridge, so that the air drawn between the web and the ridge can flow into the groove. To do. Some contact at the apex of the convex surface is preferred at this location.

Typically, the minimum gap between the web and the outer surface occurs at the maximum radius of the convex surface and the gap between the web and the convex surface increases with the axial distance from the minimum gap. The wrap angle α is in the range of 10 ° to 300 °. Means are provided for moving the web at speeds in the range of 300 to 1,000 feet per minute (91.4 to 305 meters per minute). The roller can be a floating roller or a driven roller. The convex surface has a radius of curvature in the range of 0.020 to 1.2 inches (0.508 to 30.5 mm) and the axial width of the groove is 0.020 to 0.105 inches (0.508 to 2.05 mm). 67 mm) and the ridge axial width is in the range of 0.020 to 0.105 inches (0.508 to 2.67 mm). This cylindrical roller is 1.5 to 10.0 inches (38.1 to 2 inches).
It may have a diameter in the range of 54 mm).

Rather than the circumferentially extending grooves and ridges as described above, the roller of the present invention comprises at least one helical groove formed in the outer surface along its length and having an axial width; At least one continuous helical ridge formed on the outer surface extending between the swirl portions of said spiral groove and having an axial width and a central surface with a convex surface having a maximum radius from the centerline of the roller; Contains. As in the example above, the curvature of the convex surface of the spiral ridge and the width of the spiral groove and spiral ridge and the axial direction are such that the web rises along the width of the roller at the beginning of the winding angle α during rotation of the roller. Of the spiral groove is selected so that it undulates above the swirl section of the section and into the swirl section of the groove, but away from the convex surface of the spiral ridge, whereby air drawn between the web and the spiral ridge is trapped in the spiral groove Allow it to flow in. The spiral groove and the spiral ridge are formed by at least one wire wound on the roller.

The device according to the invention and the conveying roller offer various advantages. Very thin webs are transported with good traction at increased web speeds. Web weaving and scratches are minimized by maintaining proper traction. The coefficient of friction between a very thin web and the roller of the present invention varies only modestly over a wide range of web speeds. It has the high quality surface finish of the rolled wire embodiment of the roller of the present invention and is also simple and economical to manufacture and maintain. By replacing existing rollers with the rollers of the present invention, existing equipment can be easily retrofitted to easily transport extremely thin webs.

[0016]

The above and other objects, features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiments of the present invention as shown in the accompanying drawings. Ah

The following is a detailed description of the preferred embodiment of the present invention, with reference being made to the drawings in which the same numerals represent the same elements in each figure.

FIG. 6 is a broken cross-sectional view of the web as seen in the direction of motion, which is very thin in one embodiment of the roller constructed in accordance with the present invention as the web enters at a wrap angle α on the roller 18. The engagement of the web 30 is shown. In accordance with the present invention, the flat-shaped grooves and ridges of the prior art roller are slightly geometrical with the shape taken by the extremely thin web when used with a prior art grooved roller as shown in FIG. It is replaced by a morphologically similar contoured surface. The shaped surface of the present invention can be provided on a regular cylindrical or concave roller, but the inventor has found that a concave roller is preferred for thinner webs. The inventor's recognition of the advantages of such a shaped surface was, in experience, contrary to the expectations of those skilled in web transport technology.
Prior to the present invention, the typical expectation of those skilled in the art was that surfaces shaped as used in the present invention would result in weak traction due to the expected line contact. The inventor has surprisingly found that such shaped surfaces are very effective when used with extremely thin webs.

According to the invention, the outer surface of the roller 18 is provided with a plurality of circumferentially extending grooves 42, which can be individual annular grooves or one or more continuous spiral grooves. . These grooves are ridges 4 that extend to the peripheral surface.
Separated by four. At least the central portion of the outer surface of the raised portion 44 has a convex surface when viewed in the axial cross section shown. That is, the ridge 44 has a shape that is rounded outward when viewed in the direction of movement of the web passing through the device. In the illustrated embodiment formed by, for example, diamond turning, the groove 42 has a substantially concave surface having an axial width W ₁ in the range of 0.020 to 0.105 inches (0.508 to 2.67 mm). Can have. The ridge 44 has an axial width W _{2 in} the range of 0.020 to 0.105 inches (0.508 to 2.67 mm).
Can have a substantially convex central portion on the surface 46 of the. The surface 46 can have a circular, elliptical, parabolic or similar convex shape with a central portion or apex 48 of maximum radius. When the surface 46 is circular as shown, the radius of curvature is 0.020 to 1.2 inches (0.50
8 to 30.5 mm). Groove 42
When the ridges 44 and the ridges 44 are formed and spaced in this way during the rotation of the roller 18 at the beginning of the wrap angle α, the web 30 undulates over the ridges and into the grooves along the width of the roller. As a result, the ridge and the groove are slightly separated from the surface. Since the web 30 exhibits this undulating shape at almost the beginning of the wrapping angle, the air drawn between the web and the ridge easily flows into the groove and the web engages the rollers and further along the wrapping angle. To be able to match.

FIG. 7 shows another embodiment of a roller constructed according to the present invention. In this example, the roller body 18 is wrapped with a wire 50 of circular cross section, and the spiral groove 42 and the ridge 4 are
4 and so on. The wire 50 is, for example, about 0.
It has a radius of 020 inches (0.508 mm) and is wound tightly on a roller so that a continuous swivel of the wire abuts as shown. Roller body 1
8 is 1.5 to 10.0 inches (38.1 to 254 m)
It can be cylindrical with a diameter in the range m).
A concave axial profile is advantageous when the rollers are used to carry thinner webs. A suitable concave shape is one whose diameter decreases from both ends to the center by about 0.2%.

FIG. 8 shows the radial displacement of a very thin web near the beginning of the wrap angle calculated as a function of axial position along a convex ridge on a roller shaped as in the embodiment of FIG. ing. A web 30 having a thickness of about 0.00025 inches (0.0064 mm) is about 2.
It was assumed to be wound on a roller having a diameter of 75 inches (69.85 mm). As shown, the gap between the web and the convex ridge was calculated to be a minimum at the maximum radius of the ridge corresponding to apex 48 in FIGS. On either side of the maximum radius, the gap between the web and the ridge is calculated to increase, thus indicating that air can escape into the adjacent groove.

FIG. 9 is calculated as a function of the axial position along the ridge around the beginning of the wrap angle between the web 30 and the convex ridge 44 on the roller in the shape of the embodiment of FIG. The air pressure of the contact surface which was made is shown. FIG.
Similarly, the chart shows that the calculated pressure between the web and the convex ridge decreases from a maximum at the apex 48 to a minimum at the center of the adjacent groove. The convexly shaped curved surface indicates that relatively high pressure air in the central portion of the ridge can easily flow into the lower pressure region in the groove.

FIG. 10 shows yet another embodiment of a roller constructed in accordance with the present invention. In this example,
The roller body 18 is wound with a wire 52 of essentially rectangular cross section so that the spiral groove 42 and the ridge 44 are obtained. The wire 52 may have, for example, a convex surface 54 with a radius of curvature in the range of 0.020 to 1.2 inches (0.508 to 30.48 mm) and 0.035 to 0.045 inches (0.8
Sidewalls 56 with radial dimensions ranging from 89 to 1.143 mm and 0.040 to 0.210 inches (1.016 mm).
To 5.334 mm) in the axial dimension. The wire 52 is wound tightly on the roller so that a continuous swirl of the wire is shown on the side wall 56.
It comes to abut along. Roller body 18 may be a cylinder having a diameter in the range of 1.5 to 10.0 inches (38.1 to 254 mm). A concave shape can also be used.

FIG. 11 shows the radial displacement of a very thin web near the beginning of the wrap angle calculated as a function of axial position along the convex ridge shaped for the embodiment of FIG. ing. It was assumed that a web 30 having a thickness of about 0.00025 inches (0.0064 mm) was wound on a roller having a diameter of about 2.75 inches (69.85 mm). As shown in the figure, the gap between the web and the convex ridge is calculated to be rather uniform across the ridge, showing that air can escape into the adjacent groove. I was made to do it.

FIG. 12 shows the wrap angle between the web 30 and the convex ridge 44 on the roller 30 shaped as the embodiment of FIG. 10 calculated as a function of axial position along the ridge. The air pressure on the contact surface near the start end is shown. The chart shows that the calculated pressure between the web and the convex ridge is relatively constant but decreases to a minimum at the edges of adjacent grooves.

FIG. 13 shows a 0.00025 inch (0.0064 mm) thick, 55 inch (1397 mm) roller running on a 5.2 inch (132.08 mm) diameter roller configured according to the embodiment of FIG. For polyethylene terephthalate webs of different widths, the coefficient of friction between the web and the roller drops very slightly over a range of web speeds of 1,000 feet per minute (305 meters per minute). A concave shape was used. Somewhat large drop in coefficient of friction is 15 pounds or 0.27 pounds per linear inch across the web (6.8 kg or 0.00 mm per mm).
48 kg) of tension or 25 per linear inch across the web
10 pounds or 0.18 pounds per linear inch (4.5 mm per mm) across the web as compared to a tension of 11 pounds or 0.45 pounds (11.34 kg or 0.008 kg per mm)
kg or 0.0032 kg) of web tension is observed. As shown, the roller of the present invention provides a reasonably constant coefficient of friction for very thin webs over a wide range of web speeds, similar to prior art rollers for very thick webs.

FIG. 14 is similar to FIG. 3 and is relatively thick 0.0025 inch (0.0) running on a 3.7 inch (93.98 mm) diameter roller in the shape of the mold shown in FIG.
For polyethylene terephthalate webs (635 mm) thick and 54 inches (1372 mm) wide, the coefficient of friction between the web and the roller is very small over a range of web speeds of 1,000 feet per minute (305 meters per minute). It shows a changing state. 15 pounds or 0.27 pounds per linear inch across the web (6.8 kg per mm)
Or 0.0048 kg) tension, 25 pounds per linear inch across the web or 0.45 pounds (11.3 per mm)
4 kg or 0.008 kg) tension, or 35 pounds per linear inch across the web or 0.68 pounds (1 per mm)
A slightly different change in the coefficient of friction compared to a tension of 5.88 kg or 0.012 kg) for a web tension of 10 pounds or 0.18 pounds per linear inch across the web (4.5 kg or 0.0032 kg per mm). To be observed. This clearly shows that the rollers of the invention also carry very thick webs with essentially the same performance as the rollers of the prior art.

[0028]

The present invention provides an improved roller for transporting extremely thin webs at increased web speeds without the substantial loss of traction or the risk of web damage.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a manufacturing apparatus for transporting and processing web material, of a general type suitable for use with the rollers of the present invention.

2 is a broken cross-sectional view in the direction of web motion showing engagement of a relatively thick web with a prior art grooved roller as the web enters the wrap angle α in the apparatus of FIG. 1;

FIG. 3 illustrates how the measured coefficient of friction varies with web speed for a web and roller pair of the type shown in FIG.

FIG. 4 is a broken cross-sectional view in the direction of web motion showing engagement of a very thin web with a grooved roller of the prior art as the web enters at a wrap angle on the roller.

5 illustrates how the coefficient of friction varies with web speed for a web and roller pair of the type shown in FIG.

FIG. 6 is a broken cross-sectional view in the direction of web motion showing engagement of a very thin web with an embodiment of a roller shaped as the present invention as the web enters at a wrap angle on the roller.

FIG. 7 is a schematic cross-sectional view in the direction of web movement showing engagement of a very thin web with another embodiment of a roller in the shape of the present invention as the web enters at a wrap angle on the roller.

FIG. 8 illustrates radial displacement of a very thin web calculated as a function of axial position along a convex ridge on a roller shaped according to one embodiment of the present invention.

FIG. 9: Air pressure between the contact surfaces between a very thin web and a convex ridge on a roller shaped in accordance with an embodiment of the present invention calculated as a function of axial position along the ridge. FIG.

FIG. 10 is a schematic cross-sectional view in the direction of web movement showing engagement of a very thin web with another embodiment of a roller shaped as the invention as the web enters at a wrap angle on the roller.

FIG. 11 illustrates radial displacement of a very thin web calculated as a function of axial position along a convex ridge on a roller shaped according to another embodiment of the present invention.

FIG. 12: Air pressure between the contact surfaces between a very thin web and a convex ridge on a roller shaped as the embodiment of the invention of FIG. 11 calculated as axial position along the ridge. FIG.

FIG. 13 shows how the measured coefficient of friction varies with web speed for a very thin web and a 5.2 inch (132.1 mm) diameter roller of the type shown in FIG. It is a figure.

FIG. 14 shows how the measured coefficient of friction varies with web speed for a relatively thick web and a 3.7 inch (94 mm) diameter roller of the type shown in FIG. Is.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Web supply source (storage roll) 12 ... Web of indefinite length 14 ... Processing area (coating machine) 16 ... Winding roll 18 ... Regular cylinder roller 20 ... Motor α ... Web winding angle 24 ... Circumferential groove (valley) 26 ... Peripheral surface ridge t ... Web thickness 30 ... Extremely thin web 32 ... High ridge 34 ... Low valley 36, 38 ... Ridge edge 40 ... Trapped air volume 42 ... Peripheral groove (valley) ) W ₁ ... convex surface 48 ... maximum radius central portion of the axial width 46 ... ridge of the axial width 44 ... peripheral surface elevations W ₂ ... ridges of the grooves 50 ... wire 52 ... rectangular cross section wire 54 ... convex surface of the wire 56 … Wire side wall 58… Wire bottom wall

Claims (4)

[Claims] 1. A device for transporting a web having a width, the source of the web being transported and at least one cylindrical roller having an outer surface with a length, said length being a transport. At least one cylindrical roller that is longer than the width of the web to be wound and has a portion of the web wrapped around the roller over an angle α, and has an axial width formed on the outer surface along each length. A plurality of circumferentially extending grooves spaced axially and a plurality of ridges formed on the outer surface and extending between the grooves, each ridge having an axial width and a convex surface. And a plurality of ridges having a maximum radius from the center line of the roller, the convex surface of the ridge and the axial width of the groove and the ridge being , The web is low at the beginning of the winding angle α while the roller is rotating. Selected to undulate above the ridge and into the groove along the width of the la, but away from the convex surface of the ridge, allowing the air drawn between the web and the ridge to enter the groove. A web carrier that allows you to escape. 2. A device for transporting a web having a width, the source of the web being transported and at least one cylindrical roller having an outer surface with a length, said length being a transport. At least one cylindrical roller longer than the width of the web to be wound and having a portion of the web wound on the roller over an angle α, and at least one spiral groove formed on the outer surface along the length thereof. At least one spiral groove having an axial width and at least one continuous spiral ridge extending between the swirl portions of the spiral groove formed on the outer surface, the axial width and the convex surface A convex surface of the spiral ridge and a spiral groove and a spiral ridge, the convex surface of the spiral ridge having a maximum radius from the centerline of the roller. And the axial width of, at the beginning of the angular wraps during rotation of the roller alpha,
The web is chosen to undulate along the width of the roller above the ridge swirl and into the groove swirl, but away from the convex surface of the spiral ridge, and retracted between the web and the spiral ridge. A web carrier that allows trapped air to flow into the spiral groove. 3. A roller for carrying a web having a width, the roller being a cylindrical roller having an outer surface with a length,
A cylindrical roller, the length of which is longer than the width of the conveyed web, such that during use of the roller a portion of the web is wound over the roller over an angle α; and an outer surface along the length. A plurality of grooves formed on the peripheral surface and spaced in the axial direction, each groove having an axial width, and a plurality of grooves formed on the outer surface and extending between the grooves. Ridges, each ridge having an axial width and a convex central surface,
The convex surface has a maximum radius from the center line of the roller, and a plurality of ridges, wherein the convex surface of the ridge and the axial width of the groove and the ridge have a wrapping angle during roller rotation. At the beginning of α, the web is chosen to undulate along the width of the roller above the ridge and into the groove, but away from the convex surface of the ridge, so that the air drawn between the web and the ridge is A web transport roller that allows it to flow into the groove. 4. A roller for carrying a web having a width, the roller being a cylindrical roller having an outer surface with a length,
A cylindrical roller, the length of which is longer than the width of the conveyed web, a portion of the web being wound over the roller at an angle α, and at least one helix formed along the length of the outer surface A groove having at least one axial width and at least one continuous spiral ridge formed in the outer surface and extending between swirl portions of the spiral groove,
At least 1 having an axial width and a convex central surface, the convex surface having a maximum radius from a centerline of the roller;
And the width of the spiral ridge in the axial direction of the spiral groove and the spiral ridge is such that the web has the width of the roller at the beginning of the winding angle α during rotation of the roller. The air drawn between the web and the spiral ridge is chosen so that it undulates above the swirl of the ridge and into the spiral of the groove, but away from the convex surface of the spiral groove. A web-carrying roller that allows it to flow in.