JPH067468Y2 - Impedance Roller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement of an impedance roller used in a video tape recorder (VTR).

[Problems to be solved by conventional techniques and devices]

Usually, in a VTR, an impedance roller for removing the vertical, horizontal, and front-back swings of the magnetic tape is provided by applying a predetermined tension while pressing the magnetic tape while the magnetic tape is running, thereby allowing safe running. It is arranged. This impedance roller has a cylindrical shape,
It is configured to have a predetermined weight. Conventionally, as shown in FIG. 11, for example, this impedance roller is a so-called outsert type impedance roller which is composed of a cylindrical metal roller portion 12 and a bearing portion 13 formed by injection molding resin into this hollow portion. As shown in FIG. 11 or FIG. 12, there is a so-called insert type impedance roller 21 having a roller portion 23 formed by injection molding resin on the outside of the weight portion 22.

However, in such a conventional impedance roller, in the case of the outsert type, in the manufacturing thereof, i) the roller portion 12 needs to be preheated in order to form the shaft 13 into the roller portion 12 by injection molding, and ii). Since the work of mounting the roller portion 12 in the molding die is complicated, the time required for molding becomes long, and iii).
A molding die is manufactured in accordance with the shape of the roller portion 12, and the roller portion 12 is again formed after injection molding with the die.
Must be finished in order to secure the desired roundness and surface roughness, and iv) due to the characteristics of the synthetic resin, due to the contraction of the bearing 13, the boundary between the bearing 13 and the roller 12 is There are inconveniences such as the occurrence of gaps and uneven rotation.
In addition, in the case of the insert type, in addition to the above i) and ii), v) when the molding die and the weight 22 are not ensured at the same temperature, a sink mark is generated on the outer peripheral portion of the roller portion 23, so that a high true The circularity and the cylindricity cannot be ensured, and there are problems that iv) weld lines, cracks and the like are easily generated on the outer peripheral surface of the weight 22.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the above-described conventional impedance roller, improve the basic performance of the impedance roller, and provide an impedance roller that can be mass-produced.

[Means and Actions for Solving Problems]

In the impedance roller according to the present invention, a cylindrical roller portion for contacting the outer peripheral surface with the magnetic tape and a shaft supporting portion for supporting the internal through hole on the support shaft are integrally formed, and then the outer peripheral surface of the shaft supporting portion is The weight is press-fitted and fixed to the inner peripheral surface of the roller portion with a gap.

Therefore, the roller portion including the shaft supporting portion is separately injection-molded separately from the weight during manufacturing, so that an impedance roller having high roundness, cylindricity and good surface roughness can be obtained. Further, the weight is press-fitted and fixed to the outer peripheral surface of the shaft support portion with a gap between the outer peripheral surface of the shaft support portion and the inner peripheral surface of the roller portion. Roundness can be easily maintained. Further, the molding time of the roller portion itself including the shaft supporting portion can be shortened, and post-processing is unnecessary, so that the mass productivity thereof can be improved.

Instead of press-fitting and fixing the weight on the outer peripheral surface of the shaft support portion, an engaging portion such as a protrusion or a recess is provided at a connecting portion connecting the roller portion and the shaft support portion, and the weight is attached to the engaging portion. It is also possible to press-fit and fix.

〔Example〕

1 to 8 show a first embodiment of the impedance roller of the present invention. In FIG. 1, 1 is a roller portion having a cylindrical outer peripheral surface and injection-molded with a material such as polyacetal (POM), 2 is a cylinder formed integrally with the roller portion 1 through a connecting portion 3 and concentric with the roller portion 1. Through hole 5 which is a shaft-shaped support part and in which a shaft (not shown) is to be inserted.
The outer peripheral surface is tapered from the base portions 2a, 2a. Reference numeral 4 denotes a weight for applying a required moment of inertia to the impedance roller, the outer diameter of which is smaller than the inner diameter of the roller portion 1 and an insertion hole 4a formed in parallel therewith. Roller part 1
The insertion hole 4a is crimped and fixed to the base portion 2a of the shaft supporting portion 2 in a state of being separated from the inner diameter of the weight 4. The weight 4 is formed of a material having a relatively large specific gravity such as copper or brass. In this case, the cross-sectional shape of the insertion hole 4a is circular according to the shaft support 2.

Since the impedance roller according to the present embodiment is configured as described above, the roller portion 1 can be separately injection-molded separately from the weight 4 in the manufacturing thereof, and the roller portion and the weight 4 can be integrally fixed after the molding. You can Therefore, there are drawbacks in that distortion, cracks and the like are likely to occur on the outer peripheral surface of the roller portion 1 that occurs during insert molding or outsert molding, which has been a problem in the past, and that it is difficult to mold circularity and the like with high accuracy. Can be resolved. Further, the weight 4 is manufactured in a separate process, and is fixed to the shaft supporting portion 2 only by being press-fitted into the shaft supporting portion 2, so that the post processing as in the conventional case is unnecessary. Further, after such integral fixing, an appropriate gap is secured between the outer peripheral surface of the weight 4 and the inner wall 1a of the roller portion 1, and the inner wall 1a is not pressed, so that the outer peripheral surface of the roller portion 1 is prevented. The roundness of is maintained. Incidentally, FIGS. 2 to 6
As shown in the figure, the cross-sectional shape of the insertion hole 4a may be various shapes so that the insertion hole 4a is not in full contact with the outer peripheral surface of the shaft support portion 2 but is in partial or plural line contact. Also in this case, the weight 4 is surely fixed to the shaft supporting portion 2 as in the above. Furthermore, the relationship between the shape of the insertion hole 4a and the cross-sectional shape of the shaft support portion 2 is opposite to that in the above embodiment, that is, the insertion hole 4a.
Not only may a be circular and the outer peripheral surface of the shaft support portion 2 may be uneven, but the same effect can be obtained if the cross-sectional shape is rectangular as shown in FIG.

The weight 4 is press-fitted and fixed by the shaft support 2 as shown in FIG.
The protrusions 2b, 2b formed in the above and the key-shaped recesses 4b, 4b formed in the insertion hole 4a are made to engage with each other to make the structure stronger.

FIG. 9 shows a second embodiment, in which reference numeral 7 is a projection projecting from the connecting portion 3 in the axial direction of the shaft supporting portion 2, and a plurality of rod-shaped bodies are integrally formed with the connecting portion 3. . A plurality of holes 4c corresponding to the protrusions 7 are press-fitted and fitted in the weight 4 with respect to the protrusions 7. In this case, the hole 4c and the protrusion 7
The fitting is performed at a plurality of places, and the weight 4 is securely fixed to the roller portion 1.

The number, shape, and arrangement of the protrusions 7 are selected as needed.

FIG. 10 shows a third embodiment, in which 4d is a ring-shaped projection formed at one end of the weight 4 so that it can be fitted into the ring-shaped recess 3a formed in the connecting portion 3. Has been formed. Reference numeral 6 denotes a stopper for fixing the other end of the weight 4 by welding to a part of the outer peripheral surface of the shaft support 2 by welding. Also in this case, since an appropriate gap is formed between the outer peripheral surface of the weight 4 and the inner wall 1a of the roller portion 1, and the weight 4 is assembled through the connecting portion 3, the outer periphery of the roller portion 1 is No distortion occurs on the surface, the roundness of the roller portion 1 can be maintained, and the same effects as those of the above-described respective embodiments can be obtained.

Since the weight 4 in the first to third embodiments is made of a material having a large specific gravity, the impedance roller has a predetermined moment of inertia and smoothly rotates with respect to the magnetic tape and absorbs the vibration of the magnetic tape. And bring the correct run. The weight 4 is not fixed to the impedance roller in the above-described embodiment, but can be locked and fixed by an adhesive or the like instead of press fitting.

[Effect of the Invention] The impedance roller according to the present invention has advantages such as high dimensional accuracy and simplification of the manufacturing process, and mass production.

[Brief description of drawings]

1 to 8 show a first embodiment of an impedance roller according to the present invention. FIG. 1 is a longitudinal sectional view showing the entire impedance roller, and FIGS. 2 to 6 are weights press-fitted into an insertion hole. 7 and 8 are perspective views showing another locking structure of the shaft support portion and the weight, FIG. 9 is a longitudinal sectional view showing the entire structure of the second embodiment, and FIG. FIGS. 11 and 12 are vertical sectional views showing the entire structure of the third embodiment, and FIG. 11 and FIG. 12 are vertical sectional views of a conventional impedance roller. 1 ... Roller part, 1a ... Inner wall, 2 ... Shaft support part, 3 ...
Connection part, 4 ... Weight, 5 ... Through hole, 6 ... Stopper, 7
...... Protrusion.

Claims (1)

[Scope of utility model registration request] 1. A weight is integrally fixed to provide a required moment of inertia, and while the weight is supported rotatably on a support shaft, it comes into contact with a running magnetic tape to absorb the swing of the magnetic tape. In the impedance roller, a cylindrical roller portion for contacting the outer peripheral surface with the magnetic tape and a shaft supporting portion for supporting the support shaft through an internal through hole are integrally formed, and an inner peripheral surface of the roller portion is formed. The weight is press-fitted or adhesively fixed to an outer peripheral surface of the shaft support portion or an engaging portion provided at a connecting portion connecting the roller portion and the shaft support portion in a state in which a gap is provided between the weights. Characteristic impedance roller.