JPH0322199Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a constant tension adjustment device for a tape head that can stably apply a constant tension to a tape pulled out from a tape pad. [Prior Art] For example, in a conventional tension adjustment device used to apply tension to a tape pulled out from a tape pad in a production line for electric wires and cables that require taping, there are devices shown in FIGS. 4 and 5. There is something like this. This device includes a tape head shaft 1, a receiving plate 2,
Set the tape pad A, the flat plate 3, the coil spring 4, and the clamping fitting 5 in this order, and press the flat plate 3, which has received the repulsive force of the spring 4, against one side of the pad A, so that the tape A is pulled out by the frictional force between the flat plate and the pad. It has a structure that applies the necessary tension t. [Problems to be Solved by the Invention] However, the above-mentioned device in which the entire flat plate 3 is brought into pressure contact with the tape pad has the disadvantage that the tape tension changes as the winding diameter of the tape pad A changes, causing frequent tape breakage. It was hot. That is, as the outer diameter of the tape pad decreases, the tape tension increases proportionally. This is proved by the formula below. In other words, if we consider that the pressing force F is acting on the entire flat plate 3 under the dimensional conditions shown in Figure 3, the force f applied to the minute thickness Δr part r away from the center of the pad is f=F. Δr/(r _p −r _s ) From the above formula, the rotational braking force Μ at a point r away is M=μf・r=μ・F・r・Δr/(r _p −r _s ) Also, the rotational braking force M of the entire pad A is If the braking moment is M _p , then M _p =∫ ^ro _rs μFr/(r _p − r _s )dr=μF/(r _p − r _s )=rd
r=μF/2(r _p −r _s )・(r _p ² −r _s ² )=μF/2(r _p −r
_s ) Calculating the tape tension t from the balance of the rotational moment, tr _p = M _p = μF/2 (r _p + r _s ) t = μF/2 (1 + r _s / r _p ) In this equation, r _p is a variable. Therefore, the tape tension t changes in proportion to the pad diameter. Therefore, in order to prevent the tape from breaking, conventionally,
While the tape pad is in use, the load on the coil spring is frequently adjusted using the tightening fitting 6, but this does not improve productivity. The purpose of the present invention is to eliminate such drawbacks. [Means for Solving the Problems] In order to eliminate the above-mentioned drawbacks, the present invention has a plate material that presses against the side surface of the tape pad under the repulsion force of an elastic body such as a coil spring, and the outer end of the plate material approaches the tape pad. Attach the bending angle θ, and the θ
is set to a size that satisfies the condition 0<tanθ<0.1, and is characterized in that the plate material is brought into contact only with the outer periphery of the tape pad at at least two centrally symmetrical positions until at least the amount of tape remaining is low. In the tension adjustment device with such a structure, as the diameter of the tape pad decreases, the plate material, which was previously kept in a fixed position, moves to the pad, and the pressing force of the elastic body gradually softens, so that the winding diameter of the tape pad decreases. The tape tension can be kept almost constant regardless of the situation. The details of its action will be clarified in the following section. [Embodiment] The device shown in FIGS. 1 and 2 is the same as the device shown in FIG. 3 except for the plate material that transmits the repulsive force of the elastic body to the tape pad. That is, in addition to the plate material 13 that replaces the conventional flat plate, the tape head shaft 1 includes a receiving plate 2 that supports one side of the tape pad A;
Coil spring 4 that presses plate material 13 against pad A
Then, the fastening fitting 5 using a screw or the like as a propulsion means is set. The plate material 13 has two pressing parts 13b arranged symmetrically on both sides of the spring receiving part 13a, the outer ends of which extend to the outside of the outer periphery of the pad A at its maximum diameter. , tape pad core b
The outer end side is inclined at an angle of θ in a direction toward the pad from a bending point 13c formed nearby. In addition, 2
The bending points 13c are located at equal distances from the center, and the plate material 13 has enough rigidity that the pressing force of the coil spring 4 does not allow the pressing part 13b to fully extend in a straight line (θ does not become zero). There is. In the exemplary apparatus constructed as above, _tanθ =x/(r _{p −rs} ) x=( r _p −r _s )tanθ On the other hand, if the amount of compressive strain from the natural length of the coil spring 4 is (a + λ) and the spring constant is k, then the pressing force F
is, F=k(a+λ) (where a: constant) =k{a+(r _p −r _s )tanθ} From the balance of rotational moment, μF・r _p =t・r _p t=μ・k{a+ (r _p −r _s )tanθ} Here, tanθ in the above equation is sufficiently small (r _p −r _s )
If tanθ is close to zero, the tape tension t is approximately t
=μka can be constant. As can be seen from this, although the bending angle θ of the plate material 13 is exaggerated in the drawing, it is actually a small angle in order to keep the tape tension t constant. If the value of θ is large, depending on the diameter difference between the maximum and minimum tape pads, the width of tape a, the dimensions of plate material 13, etc., when the remaining amount of tape becomes low, the outside of the plate material that moves toward the pad side A situation occurs in which the end hits the backing plate 2 and the tape pad separates from the plate and no tape tension is applied. Therefore, in order to prevent this, θ is made a very small angle. tanθ=0 or more ~ 1.1
If the amount is below, contact of the plate material to the receiving plate can be prevented and the value of t can be stabilized. A more preferable numerical value determined empirically is tanθ=0.05 to about 1.07. More detailed examples are given below. Using an aluminum plate 13 with dimensions of each part shown in Figures 1 and 2 as shown in the table below,
A polyethylene tereftate (PET) tape of 0.012 mm and width w = 7 mm is placed on the core of radius d = 36 mm r _p =
Spring pressure was applied to tape pad A wrapped to 110.5 mm.

[Table] The bending angle θ of the plate material was varied as shown in the table below, and the number of times the tape broke under each condition was investigated, and the results shown in the table were obtained.

[Table] In addition, when we investigated the change in tape tension when tanθ=0 and when tanθ=0.7, we obtained the results shown in FIG. 3, and when tanθ=0, it was necessary to adjust the lateral pressure midway. In addition, in the illustrated device, the plate 13 is brought into contact with the tape pad at two points at 180° different positions, but the number of pressing parts of the plate may be increased to make contact at three or more points within a range that does not interfere with tape withdrawal. Alternatively, the outer end may be in line contact with the outer periphery of the tape pad except for the tape pull-out portion. Furthermore, since the spring pressure on the pad whose diameter has become smaller decreases as the remaining amount of tape decreases, there is no need to worry about the tape breaking even if the plate material hits the side surface flatly.Therefore, the bending point 13C is It may be located slightly outside the outer diameter of the core. [Effects] As described above, according to the present invention, the plate material that applies the repulsive force of the elastic body to the tape pad is given a slight angle, and the plate material contacts only the outer periphery of the tape pad at least until near the final point of tape feeding. Since the pressing force of the elastic body decreases as the remaining amount of tape decreases, the tape pulling force can be kept almost constant at all times, and therefore the tension adjustment during tape feeding is easy. This eliminates the need for tape breakage.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view showing an example of the constant tension adjustment device of the present invention, Fig. 2 is a front view thereof, Fig. 3 is a comparison graph of changes in tape tension, Figs.
The figures are a side view and a front view of a conventional device. 1... Tape head shaft, 2... Receiving plate, 13...
... Plate material, 13a ... Spring receiving part, 13b ... Pressing part, 13c ... Bending point, 4 ... Coil spring, 5 ...
...Tightening metal fittings, A...Tape pad.

Claims (1)

[Scope of utility model registration request] In a device that applies the repulsive force of an elastic body to a tape pad through a plate material along the side of the tape pad, and adjusts the tape pull-out tension by the frictional force between the plate material supported by the tape pad shaft and the tape pad that passes through the tape pad shaft as the center. , a slight bending angle θ is attached near the tape pad core portion of the plate material so that the outer end approaches the tape pad, and the θ is 0<
A constant tension adjustment device for a tape head, which has a size that satisfies the condition of tanθ<0.1, and is characterized in that a plate material is brought into contact only with the outer periphery of the tape pad at at least two centrally symmetrical positions until at least the amount of tape remaining is low.