JPH0516539B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a tension meter.

To measure the tension of long linear objects, tapes, sheets (hereinafter simply referred to as long objects),
It is common to use three rotatable rollers, attach a long object to each roller in turn, and measure the tension from the displacement of the sensing roller in the center due to the tension of the long object. Are known. However, in the past, tension has been measured only from the displacement of the sensing roller, so accurate tension measurement cannot be expected.

That is, in the measurement method using three rollers as described above, the attitude of the detection unit made up of the rollers becomes a problem. In other words, if the direction of displacement of the sensing roller due to the tension and the direction of gravity acting on the sensing roller are always perpendicular, there is no problem, but if the direction of displacement is not perpendicular but tilted, the sensing roller will not be elastically The original tension and the vertical component of the weight of the detection unit act on the supporting spring. This adds an error to the tension determined only from the displacement amount of the sensing roller. Conventionally, in this type of tension meter, there is no known example in which an attempt has been made to eliminate the influence of errors due to the orientation of the detection section.

This invention measures the tension of a long object to be measured from the amount of displacement of the sensing roller.
The purpose is to avoid errors caused by the weight of the detection unit.

Before explaining the embodiments of the present invention, the relationship between the displacement amount of the sensing roller and the tension will be explained. Figure 1 shows the detection section of this type of tension meter, where 1 is a sensing roller, 2, 3
4 is a guide roller, and 4 is a long object to be measured.
Each radius of rollers 1 to 3 is R, R ₁ , R ₂ , long object 4
The diameter or thickness (hereinafter simply referred to as the diameter) of D,
The horizontal axis distances between roller 1, roller 2, and roller 3 are A ₁ , A ₂ , and roller 1 and roller 2 when no tension is applied to roller 1 (indicated by the two-dot chain line in the figure). The vertical axis distance with 3 is
B ₁ , B ₂ , x is the vertical displacement of the axis of the roller 1 when tension is applied to the roller 1, and T is the tension applied to the elongated object 4.

Let θ 1 and θ 2 be the angle of each long object portion from the contact point with the long object 4 of the roller ₁ to each roller 2, ₃ with respect to a vertical line passing through the axis of the roller, and each of the long object portions The force acting on roller 1 due to the tension of
If F ₁ and F ₂ are used, the relationship between them is shown in a vector diagram as shown in FIG. 2. Furthermore, if the line passing through the center of the long object 4 is M as shown by the dashed-dotted line in the figure, then the straight part of the line M between the rollers 1 and 2 is extended left and right, and the axis of the roller 1 is O and its axis O
P ₁ is the distance between the intersection point N ₁ with the vertical line passing through the roller 2, P ₂ is the distance between the axis O ₁ of the roller 2 and the intersection N ₂ with the vertical line passing through the axis O ₁ , If the vertical distance between the intersection points N ₁ and N ₂ is Q, then the relationship between them can be expressed geometrically as shown in FIG.

From the spectral diagram in FIG. 2, Tcosθ ₁ +Tcosθ ₂ =Kx (1) where K is the constant of the spring acting on the roller 1 in the opposite direction to the tension. Also _{, from Figure 3 ,} P _{2 - ( B 1 + 1} = A ₁ (R + R ₁ + D) - (B ₁ - x)√A ²
/ ₁ + (B ₁ + x) ² - (R + R ₁ + D) ² / A ² / ₁ + (B ₁ + x
) ² Find cosθ ₂ using the same method, cosθ ₂ = A ₂ (R + R ₂ + D) − (B ₂ − x) √A ²
/ ₂ + (B ₂ + x) ² - (R + R ₂ + D) ² / A ² / ₂ + (B ₂ + x
) ² By substituting the above equation into equation (1), the tension T can be found. Here, for example, A ₁ =A ₂ , B ₁ =B ₂ , R=
If R ₁ = R ₂ In other words, when the long object 4 is attached to each roller, if the roller 1 is displaced by x, then
By substituting (2) into equation (2), the tension T of the long object 4 at that time can be found. The relationship between T and x cannot be expressed only by the above formula,
According to other methods, other relational expressions also hold true. Therefore, the above equation is expressed as a general equation T=F(x) (3).

However, this equation holds true for an ideal long object with no rigidity. If the error in tension measurement due to stiffness can be ignored, the above equation may be used as is, but if it is not, it may be corrected to a relational equation that takes stiffness into account. Rigidity is related to the diameter of a long object, so if the displacement _of the sensing roller is _{set to} Instead, it can be calculated by substituting it into equation (3). An example of the relational expression between X ₀ and X ₀₀ is as follows. However, K ₀₁ , K ₀₀ , K ₁₁ , and K ₁₀ are constants, and can be determined from the relationship between displacement and tension of a long object of known diameter for the same long object to be measured.

X ₀ = (X ₀₀ −K ₀₁・D ₀ −K ₀₀ )/K ₁₁・D ₀ +K ₁₀ ) (4) Actually, X ₀ obtained from the above equation is further substituted into the function equation of equation (3). If it is troublesome to calculate the function value for each variable X ₀ ,
It may be stored in ROM and read out using X ₀ as an address.

Next, the influence of the weight of the movable part in the detection unit on measurement will be explained. The purpose of the present invention is to avoid this influence. Assume that the arrangement of rollers 1 to 3 is inclined as shown in FIG. 4a. If the angle in the direction of displacement of roller 1 due to tension with respect to the horizontal line is α, then the mass of the movable part of the detection unit is W (gr), and the gravitational acceleration is g (CN/gr).
Then, from the analytical diagram in Figure 4b, the force f exerted on the spring that provides elasticity that opposes the displacement of roller 1 is f=g・W・sinα This force f will displace roller 1 due to its original tension. This will act on the spring in addition to the force F. Therefore, equation (1) can be expressed as Tcosθ ₁ +Tcosθ ₂ +f=Kx. From now on, T=Kx-f/cosθ ₁ +cosθ ₂ = (1-f/
Kx) (Kx/cosθ ₁ +cosθ ₂ ) In the above equation, Kx/cosθ ₁ + cosθ ₂ is the tension value when the displacement direction of roller 1 is ignored, and if this is f(x), then T = (1- f/Kx)・f(x) In addition, when the tension is 0 and the gravity acting on the roller 1 does not act in the direction of displacement of the roller 1, specifically, when the gravity and the displacement direction are perpendicular to each other ( In this case, the influence of gravity does not occur in the direction of displacement of roller 1.) Let the position of roller 1 be x ₁ . In addition, in the actual measurement state, regardless of whether the gravity acting on roller 1 and the direction of displacement of roller 1 are perpendicular or non-perpendicular, the position of roller 1 at the time of measurement is x ₂ (however, the tension is 0).
Suppose that ). And the amount of displacement at both positions (x ₂
−x ₁ ) as xt, f=Kx _t Therefore, the above equation is T=(1−x _t /x)・f(x) (5) From the meaning of the above equation, the displacement of roller 1 is If we calculate the tension f(x) from the quantity x, and also substitute x and x _t with f(x), we get
Tension T that avoids errors due to the detection part's own weight
You will be able to ask for

Embodiments of the present invention will be described below with reference to FIG. 5 and subsequent figures. 5 is a base frame, 6 is an arm that supports guide rollers 2 and 3 at regular intervals, and 7 is a vertically movable rod that supports arm 6, and a spring 8 is interposed between its lower end and base frame 5. The rod 7 is provided with a downward force due to its elasticity.
1A is a rod that can be raised and lowered to support the sensing roller 1, and this is an arm 10 connected to the tip of a plate-shaped spring 9 whose base end is supported by the base frame 5.
It is connected to. Therefore, when the roller 1 moves up and down, the rod 1A also moves up and down against the elasticity of the spring 9. Spring 9 is a spring with a spring constant K in equation (1).

11 is a position detection device that detects the position (displacement) of the roller 1. Here, the displacement of the rod 1A is detected using a CCD.
It is detected by a type image sensor. 12 is a light emitting element for detection, and 13 is a light receiving element arranged in the vertical direction. Since the light emitting element 13 is installed on the rod 8, the receiving point of light from the light emitting element 12 changes according to the displacement of the rod 1A. Rod 1 depending on which light receiving element receives the light.
The amount of displacement of A can be detected.

A correction device 15 corrects the position of the rollers 2 and 3 with respect to the roller 1, and corrects the position of the rollers 2 and 3 in accordance with the diameter of the elongated object 4. In other words, block 16 integrated with rod 7
The correction device 15 is constructed by installing a base frame 5 and an integrated arm 5A opposite to each other, and a block 16 and an arm 5A having the same diameter as the long object 4 to be measured are arranged between the block 16 and the arm 5A. Clamp the gauge 17. This allows the rod 7 to be adjusted by the diameter of the gauge 17.
is displaced upward. Due to this displacement, the roller 2,
3 will be displaced, so if the tension exerted by the long object 4 on the roller 1 is the same, regardless of the diameter of the long object 4, the long object 4 to which the roller 1 is attached will be displaced. The angles of object 4 (angles θ ₁ and θ ₂ in FIG. 2) are almost the same. In other words, even if the tension is the same, if the diameter is large, the angle should be small, but if the rollers 2 and 3 are raised by the diameter, the diameter will approximately become zero. The angle will be changed to that at . As described above, regardless of the size of the diameter, the angle will be almost the same for the same elasticity.

The diameter described above is detected by the wire diameter detection device 18. This is so that the wire diameter is detected from the displacement of the rod 7. This is also an example of CCD
It is composed of a type image sensor. 19 is a light emitting element for detection, and an arm 20 integrated with the rod 7
21 are light receiving elements arranged in the vertical direction. Also in this case, the amount of displacement of the rod 7 is detected from a light receiving element that receives light from the light emitting element 19 based on the displacement of the rod 7, and the wire diameter is determined from this. Note that one light receiving element 13, 21 may be used in common.

According to the above explanation, from the configuration shown in FIG.
It will be understood that the displacement amount of the roller 1 and the wire diameter of the elongated object 4 can be detected by each of the detection devices 11 and 18. Note that since the rod 7 is urged by the spring 8 with a force greater than the reaction force of the roller 1 (the elasticity of the spring 9), the rollers 2 and 3 will not be displaced in the vertical direction during the measurement.

The detection values from each detection device 11, 18 are given to an arithmetic and control device 24 of a microcomputer 22 shown in FIG. Separate read-only memory (ROM)
25 are available. As mentioned above, the function value of equation (3) is stored for the variable X ₀ obtained by calculation, with X ₀ as the address. This is convenient because execution of the calculation in equation (3) can be omitted.
Needless to say, the stored data in this case will be a value that takes into account corrections for variations in the individual parts of the mechanical system constituting this measuring mechanism and during assembly.

In the measurement, a long object 4 is sequentially attached to each of the rollers 1 to 3 as shown in FIG. At this time, the tension of the elongated object 4 causes the roller 1 to be displaced downward. This amount of displacement is detected by the position detecting device 11, and the detected value is given to the arithmetic and control device 24 of the microcomputer 23 in FIG. 6 together with the detected value by the wire diameter detecting device 18. The arithmetic and control device 24 calculates X ₀ using the detection values of both the detection devices 11 and 18 according to equation (4). Then, using this X ₀ as an address, the tension T shown in equation (3) is read out from the read-only memory 25.
Note that when ignoring the influence of the rigidity of a long object, the displacement position of the sensing roller can be used instead of X ₀ determined by equation (4).
X ₀₀ may be used as is. The tension T read from the memory 25 is used by the arithmetic and control unit 24 as f(x) in equation (5) to perform the calculation in equation (5).

Specifically, the reference position of the roller 1 when the tension applied to the roller 1 of the long object 4 is zero (the angle α in FIG. 4 is 0 degrees, that is, the gravity acting on the roller 1 and the direction of displacement of the roller 1) The amount of displacement _xt from the vertical position) is stored in the RAM of the storage device 23 of the microcomputer 22 based on a command from the storage command device 21. Then, in the above calculation, this stored value is read out, and the calculation control unit 24 executes the calculation of equation (5) using the detection value of the detection device 11 and the previous tension T. The calculated value is a true tension value that avoids the influence of the detection unit's own weight, and is displayed on the display device 26.

As described in detail above, according to the present invention, it is possible to perform extremely accurate tension measurement while avoiding the influence of the sensing roller's own weight due to its inclination.

[Brief explanation of the drawing]

Fig. 1 is an enlarged front view of the detection part to explain the principle of tension measurement, Fig. 2 is a vector diagram of Fig. 1, Fig. 3 is an analysis diagram of the same, Fig. 4a is a front view of the detection part, FIG. 4b is an analysis diagram of the same, FIG. 5 is a perspective view showing an embodiment of the present invention, and FIG. 6 is a block diagram showing the calculation configuration. 1...Sensing roller, 2, 3...Guide roller, 11...Position detection device, 18...Wire diameter detection device, 21...Storage command device, 23...Storage device, 26...Display device.

Claims (1)

[Scope of Claims] 1. Two guide rollers, a sensing roller disposed between the two guide rollers and displaced by the tension of the object to be measured, and the object to be measured of the sensing roller. a first detection means for detecting a displacement amount x based on the tension of the sensing roller; a first calculation means for calculating the tension f(x) based on a detected value by the first detection means; The position x ₁ of the sensing roller when the direction of displacement due to the gravitational force is perpendicular to the direction of gravity acting on the sensing roller and the tension is zero, and the sensing roller at the time of actual measurement when the tension is zero. a second detection means for detecting the amount of displacement (x ₂ −x ₁ =xt) with respect to the position x ₂ of (x), and a second calculation means that calculates (1-xt/x)·f(x) and uses the calculated value as the desired tension.