JPH04365746A - Web guide roll - Google Patents

Abstract

PURPOSE:To eliminate generation of a slip and a rubbing flaw relating to a web even in the case of conveying the web of Ra=0.005 to 0.03mum surface roughness further with 3 to 15mum thickness, in the case of a web guide roll in a web conveyer. CONSTITUTION:A groove is engraved by a 50% or more land rate in a surface of a web guide roll so that mean surface roughness of a land part is obtained in a range of Ra=1.0 to 3.0mum.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a web guide roll that guides the web in a web conveying device that conveys the web of the tape when manufacturing magnetic tapes used in audio, video, computers, etc. It is.

0002

2. Description of the Related Art When manufacturing a magnetic tape, a plastic web as a substrate and a magnetically coated web are transported from a web supply roll by a web conveying device.
For example, it is conveyed through a cleaning and preparation section, a coating section, a subsequent drying channel, a checking device and a calender to a winding roll.

[0003] Since conveying the web under high tension may cause damage to the web, and furthermore, in order to convey the web through all of the above-mentioned working sections, the above-mentioned web conveying apparatus generally has a A plurality of drive units are provided. As this drive unit, a suction roll that conveys the web by vacuum suction is known. Further, a suction roll that requires less power for vacuum use and can be driven at high speed is disclosed in Japanese Patent Publication No. 56-12938.

[0004] A web guide roll is provided between the plurality of drive units described above to change the direction of the web and guide its running. This web guide roll is in contact with the web at a predetermined wrap angle, and due to the frictional force between the web and the roll surface and the force of pulling the web by the drive unit, the web conveyance speed and the web guide roll circumferential speed are the same. It can be rotated so that In this case, if the guide roll and the web are not held together, the web will slip against the guide roll and the web will be damaged.

In general, the factors that determine the holding force with which the guide roll holds the web include web tension, wrap angle, web conveyance speed, web surface roughness, and roll surface roughness.

[0006] Among these, the tension of the web has the problem of damaging the web, so it is difficult to increase the tension in order to increase the holding force. Normally, this tension is 2 to 15 kg in the magnetic tape manufacturing process.
The value is . The wrap angle cannot be changed due to equipment constraints, and is generally set at a wrap angle of about 90° to 270°. The web conveyance speed is determined by economic reasons and productivity, and is not variable. Furthermore, the surface roughness of the web is determined by the quality of the magnetic tape, etc., and cannot be changed.

Therefore, in order to control the holding force of the web in the guide roll, it is very important to control the surface roughness of the guide roll, which is the only variable element.

[0008]

Problems to be Solved by the Invention The surface roughness of conventional webs was relatively rough, with Ra=0.05 μm or more. Therefore, even if the surface roughness of the guide roll changed due to wear or the like, problems such as slipping did not occur. However, in recent years, S-V
As exemplified by HS and Hi-8, the surface roughness of the web improves as the density of the magnetic medium coated on the web increases, resulting in extremely smooth ultra-high-quality materials with an Ra of 0.005 to 0.03 μm. Smoothened webs are increasingly being used.

[0009] For this reason, even the web guide rolls, which were conventionally capable of transporting the web without slipping, are unable to hold the web when transporting this ultra-smoothed web, and slippage occurs. It may occur.

In order to maintain the holding force of the web in the guide roll, the surface roughness of the guide roll is controlled as described above, and the sum of the surface roughness of the web and the surface roughness of the guide roll (however, this sum is It is important to keep the surface roughness Ra (which is not determined simply by the sum of the surface roughness Ra of the web and the surface roughness Ra of the guide roll) within a certain range of values. Further, when the surface roughness of the guide roll is increased in order to improve the holding force, if the roughness is too large, it will cause scratches on the web, causing a defect more serious than slippage. For this reason, it is not a good idea to simply increase the surface roughness of the guide roll.

[0011] In view of the above circumstances, the present invention has been developed for S-VHS and H
It is an object of the present invention to provide a web guide roll that does not cause slippage or scratches on the web even when conveying an ultra-smooth web such as i-8.

0012

[Means for Solving the Problems] The web guide roll according to the present invention has a surface roughness of Ra=0.005 to 0.03.
A web guide roll that travels and guides the web in a web conveying device that conveys a web with a thickness of 3 to 15 μm, wherein grooves are carved on the surface of the roll with a land ratio of 50% or more. ◆The average surface roughness of the land portion is in the range of Ra=1.0 to 3.0 μm.

[0013] The land portion here refers to the portion of the surface of the web guide roll that is in direct contact with the web, excluding the groove portion, and the land ratio is the ratio of the land portion to the effective surface area of the guide roll. It means something.

[0014] Furthermore, Ra represents the center line average roughness of the surface roughness defined by the JIS standard. This center line average roughness refers to the roughness curve by extracting a portion of measurement length L from the roughness curve in the direction of its center line, taking the center line of this sampled portion as the X axis, and the vertical magnification direction as the Y axis. When expressed as y=f(x), Ra given by the following formula
The value expressed in microns is called centerline average roughness.

[0015]

[Math 1]

[0016]

[Operation] The web guide roll according to the present invention has grooves formed on its surface with a land ratio of 50% or more, and the average surface roughness of the land portion is in the range of Ra=1.0 to 3.0 μm. Therefore, even when guiding an ultra-smooth web with a surface roughness of Ra = 0.005 to 0.03 μm and a thickness of 3 to 15 μm, the web may slip or scratches may occur on the web. This makes it possible to prevent

[0017]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic illustration of an example of a web conveying device using web guide rolls according to the present invention.

This web conveying device includes a driving means for conveying the web, that is, a suction roll 1 for controlling the web conveyance speed and the traction force of the web, and for accelerating and decelerating as necessary; direction changing rolls 2a, 2b which are mutually movable to adjust the wrap angle thereof, web guiding rolls 3a to 3d according to the invention for changing the direction and guiding the web, and a two-armed lever 4a; adjustable weight 4b
It is composed of a dance roll 4 loaded by a roller. As shown in FIG. 2, diamond-shaped V grooves are carved on the surfaces of the web guide rolls 3a to 3d so that the land ratio is 50% or more. In addition, the web guide roll 3a~
The average surface roughness of the land portion of 3d is Ra=1.0 to 3.
It is processed to be within the range of 0 μm.

[0020] Surface roughness Ra=0.005 to 0.03
An ultra-smooth web 5 having a thickness of 3 to 15 μm is driven by a suction roll 1, direction-changed and guided by web guide rolls 3a to 3d, and conveyed in the direction of the arrow shown in FIG. At this time, the dancing roll 4 corrects conveyance speed fluctuations and web tension fluctuations. That is, the dancing roll 4 controls a drive device (not shown) of the suction roll 1 by performing an up-and-down motion. For example, if Zo is the required web traction force on the web outflow side of the suction roll 1, and Z is the tension that can be measured at any point in front of the suction roll 1, then when Zo>Z, the traction force of the transported web decreases, i.e. Braking occurs, and when Zo<Z, an increase in traction force or acceleration occurs.

[0021] Surface roughness Ra=0.005 to 0.03
A web guide roll having a surface roughness that does not cause slippage or scratches when guiding an ultra-smooth web having a thickness of 3 to 15 μm has been investigated and will be described here.

FIG. 3 is a characteristic curve diagram of the web conveyance speed V and the slip amount S for web guide rolls having three types of surface roughness investigated. Curves A, B and point C in FIG. 3 correspond to web guide rolls A, B and C, respectively, having the following surface roughness:

A) Ra=0.5 μmB) Ra
= 1.5 μm C) Ra = 5.0 μm The specifications of the roll used at this time are shown below.

[0024]Outer diameter 300mm, V-shaped groove (see Figure 4(a)), depth 0.25 x width 0
．． 25mm, pitch between grooves 1.5mm Perforation hole diameter 1.5mm, perforation hole pitch 48mm x 20° Wrap angle 90° Also, the surface roughness of the web used is Ra
=0.007 μm.

As is clear from FIG. 3, the surface roughness of roll A is too small, and the web conveyance speed V is 200 m/mi.
Slip occurs from point n. In addition, the surface roughness of roll C is too large, and the web conveyance speed V is 100 m/
Scratches occur on the web at the point of min. Roll B has a surface roughness Ra of 1.5 μm, and Ra is within the range of 1.0 to 3.0 μm. Therefore, the web was guided without slipping at a web conveyance speed V of 500 m/min, and no scratches were generated. Here, the web conveyance speed V is 6
Although slippage occurs at a speed exceeding 00 m/min, since the amount of slippage S in this case is small relative to the web conveyance speed V, it does not pose much of a problem.

Therefore, the surface roughness Ra=1.0 to 3
．． By using guide rolls in the range of 0 μm, it is possible to avoid slippage and avoid scratches on the web.

In the above-mentioned embodiment, the cross-sectional shape of the groove was V-shaped as shown in FIG. 4(a).
b) It goes without saying that the groove may have any shape, such as a U-shape as shown in (b).

Furthermore, in the above-described embodiment, the grooves are carved on the surface of the web guide roll so as to form a diamond-shaped model, but these grooves must be carved so that the web land ratio is 50% or more. For example, as shown in FIG. 5, it may be carved parallel to the roll axis, or it may be carved in a ring shape or a spiral shape in the circumferential direction.

[0029]

Effects of the Invention As explained above in detail, the web guide roll according to the present invention has a surface roughness of Ra=0.005.
~0.03 μm and a thickness of 3 to 15 μm
- It does not slip or scratch even on ultra-smooth webs such as magnetic tapes typified by VHS and Hi-8. Therefore, the web can be transported efficiently, and productivity of magnetic tapes and the like can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a web conveying device using a web guide roll according to the present invention.

FIG. 2 is a diagram showing an example of a state in which grooves are carved on the surface of the web guide roll according to the present invention.

[Figure 3] Characteristic curve diagram showing the relationship between web conveyance speed and slip amount

[Figure 4] Enlarged cross-sectional view showing the shape of the grooves carved in the web guide roll

FIG. 5 is a diagram showing another example of a state in which grooves are carved on the surface of the web guide roll according to the present invention.

[Explanation of symbols]

1 Suction roll 2a, 2b Direction change roll 3a-3d Web guide roll 4 Dance roll 5. Ultra-smooth web

Claims (1)

[Claims] Claim 1: Surface roughness Ra=0.005 to 0.
A web guide roll for guiding the web in a web conveying device that conveys a web having a thickness of 0.03 μm and a thickness of 3 to 15 μm, the roll having grooves carved on its surface with a land ratio of 50% or more. , a web guide roll characterized in that the average surface roughness of the land portion is in the range of Ra=1.0 to 3.0 μm.