JPS5913279Y2 - steel cord - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a steel cord used for vehicle tire cords, belt cords, and the like.

Recently, there has been a strong demand for this type of steel cord to be cheaper and of better quality than ever before.

For this reason, recently, in order to make steel cords cheaper, a double-twist puncher stranding machine is used, and in order to improve fatigue resistance, the strands are twisted in the same direction and at the same pitch, but this is still not the case. A product that meets the requirements has not been obtained.

In other words, the conventional steel cord is made by twisting a plurality of strands 1 using a cylindrical twisting machine or the like to form a strand 2 as shown in Fig.
was making.

This method requires a large number of steps and is very expensive because it is difficult to use a double-twisting machine, and it also has the drawback of poor quality such as fatigue resistance.

On the other hand, it has recently become widely known that twice-twisting wire twisting machines are much more efficient than once-twisting wire twisting machines such as cylindrical twisting machines. In addition, steel cords with multiple strands twisted into a multi-layer structure as shown in Figures 3 and 4 using triple-twisting machines began to be adopted. It is said that

However, it still has the disadvantage that the twist is not uniform and neat, and the cross-sectional shape and longitudinal straightness are not good.

In other words, in a double-twisting wire twisting machine, the wires or wire groups to be twisted are twisted due to its structure, so when twisting a steel cord with a multilayer structure as shown in Figures 3 and 4, the twisting direction is different between processes. When the twist is reversed, the twist from the previous process returns and the strands, etc. are exposed to the surface, and when the twist direction is the same, the outer strands are not tied together (there are more gaps), etc. It has the disadvantage that phenomena can occur.

In addition, when twisting steel cord with a double-twisting feeding machine, a false twisting device is used that twists the wire to a twist pitch smaller than the finished twist pitch during the twisting process in order to remove the internal stress of the wire and shape it into a twisted shape. As is well known, in the case of multi-strand twisting, the twisting occurs before and after the false twisting roller, and the effect remains even after finishing, making the twisted shape unstable and physically unstable.

The present invention aims to eliminate the drawbacks of the double-stranded steel cord made by the double-stranded wire twisting machine as described above, and to provide a high-quality, inexpensive multi-layered steel cord.

As a result of repeated numerous experiments, we found that the pitch of strand twisting in the strand process, the pitch of core twisting in the core twisting process, the pitch of sheath twisting in the sheath twisting process, and the pitch of sheath twisting in the cord twisting process in the cylindrical wire twisting machine. Since the pitch length of cord twisting is determined respectively, these pitches do not change between each process.

In other words, the base wire group does not expand or contract in the next process, but in a double-twist wire twisting machine, the twist pitch changes throughout the entire process (core process, sheath process, cord process, etc.).

That is, the twisting in the sheathing process also affects the core, the twisting in the cording process affects both the core and the sheath, and the twisting pitch of the core and the sheath change during the cording process.

Moreover, during these steps, the twist rate (length reduction rate based on twist) changes between each layer, and this is the cause of the above-mentioned adverse effects.

In order to eliminate these drawbacks of the twice-twisted wire twisting machine and obtain beautifully twisted steel cord, it is necessary to minimize the variation in the twisting rate, and furthermore, to reduce the difference in the twisting rate between each layer. was found to be suitable.

In other words, by making the twist rate between each layer almost the same in the state of the finished (product) twist pitch, even if twisting is performed during the twisting process and false twisting of each layer, the shortening rate between each layer will be reduced. As a result, the results are very similar to each other, and therefore, the twist disorder is eliminated, and a steel cord with a clean twisted state is finally obtained.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in Figures 3, 4, and 5, two or three layers of strands with approximately the same diameter are twisted in the same direction, and the pitch ratio of each layer is set to Del, the effective diameter of the innermost layer, and the strands are twisted in the same direction. If the diameter is d, when twisted into n layers, approximately (Del+2(n -1)
) d) : (De l+2(n +2) d) :
(De l+2(n −3) d ) (However, in the case of two layers, n=2, and in the case of three layers, n=3).

In other words, in the case of two layers, approximately (De l+2
d): In the case of De 1.3 layers, from the outer layer approximately (Del+4 d): (Del+2 d):
Configure the steel coat as Del.

With this structure of steel cord, even if each layer is twisted using a double-twisting wire twisting machine, a stranded wire can be produced which does not have the drawbacks of the conventional method, such as poor twisted shape and instability in the longitudinal direction.

In other words, in the case of three layers, the twist rate, twist pitch, and effective diameter of each layer are λ□, λ2. λ3. P.I.

P2. P3. Deo, De2. If De3 is used, then the twist ratio of each layer is the same.

Naturally, the case of two layers can also be considered in the same way.

In addition, there are many other possible structures for this steel cord, such as 4+10+16 as shown in Figure 6, 5+11+17 as shown in Figure 7, and 1+6+12 as shown in Figure 8, but it should be determined appropriately depending on strength, flexibility, and other qualities. .

As an example, the pitch ratios in these cases are shown in the table below.

In addition, the steel cord of the present invention tends to have a perfectly circular cross section compared to when twisted in the same direction and at the same pitch, and when twisted in the opposite direction, it becomes a point contact, but it becomes a line contact. Fatigue resistance was also improved as shown in FIG.

Note that one or more wrapping wires may be wound spirally around the outer periphery of these steel cords.

As described above, the steel cord of the present invention can be freely selected between strength and flexibility, has a neat twisted state, is excellent in fatigue resistance, and is inexpensive, and its effects are remarkable.

[Brief explanation of the drawing]

Fig. 1 shows a conventional steel cord, A is a side view, the opening is a sectional view, Fig. 2 A is a sectional view of a single-layer steel cord, and Figs. FIG. 5 is a side view of FIG. 4, and FIGS. 6, 7, and 8 are sectional views of a steel cord showing other embodiments of the present invention. FIG. 9 is a curve diagram showing the results of a fatigue test of the present invention and a conventional steel cord. 1...Element wire, 2...Strand, 3.
·····code.

Claims (1)

[Scope of utility model registration request] In a steel cord made by twisting strands of approximately the same diameter into two or three layers using a double-twisting machine, the direction of twist is the same, and the ratio of the finished twist pitch of each layer is the same as that of the inner layer. When the diameter is Del and the wire diameter is d, when twisted into n layers, approximately (Del + 2 (n = 1) d): (Del +
2(n-2)d): (Del+2(n-3)d) (However, in the case of two layers, n=2, and in the case of three layers, n=3). code.