JPS638348B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous method for manufacturing hoses.
More particularly, the present invention relates to a continuous method for manufacturing a hose incorporating a layer of metal reinforcement. Although the hose of the present invention has a variety of uses, one of the applications in which it can be used extensively is for the conveyance of hydraulic oil used in the hydraulic systems of agricultural and construction machinery, for example. .

Recently, the use of fibrous materials, such as polyethylene terephthalate polyester fibers known as "Dacron" (trademark), as reinforcement layers has been implemented in the thermoplastic hose industry. More recently, aromatic polyamides such as Kevlar® have also been used as reinforcing layers in thermoplastic hoses. The reinforcement layer can provide strength and burst resistance to the hose in which it is used. What is now desired is to provide a reinforcement layer that imparts substantial kink resistance to the hose and exhibits the desired reinforcing action while still being sufficiently flexible.

A number of different types of hose structures have been developed over the years. Each of these hose structures has various desirable characteristics and uses a wide variety of materials. Additionally, a number of different techniques have been utilized to bond the reinforcement layer to the outer surface of the core tube.
As a recent example, for example, U.S. Patent No. 3944453
(the reinforcement layer and core tube are mechanically interlocked). However, for the technique taught in this U.S. patent,
It is necessary to use a special thermally formed and fused bonding layer.

Another example of a reinforced thermoplastic hose that is of the mechanically interlocking type and again requires the use of a special layer is the one described in U.S. Pat. No. 3,945,867. be.

In addition to thermoplastic hoses of the textile reinforcement type, rubber hoses with metal or steel wire reinforcements have also been proposed. For example, U.S. Pat.
It is number 3776794. Here, the core tube must first be supported by an internal mandrel and then the tube must be hardened.

In some examples, a metal reinforcement is provided above a core tube constructed of a material other than rubber, such as a thermoplastic material. However, in such cases the bonding layer is either absent or very poorly present.

It is an object of the present invention to overcome the above-mentioned disadvantages of hoses, namely, that the metal reinforcement is mechanically interlocked with the thermoplastic core tube and advantageously also interlocked with the cover. Our goal is to provide a manufacturing method for hoses that are as simple as possible.

According to the invention, a core tube of thermoplastic material is first formed. A metal reinforcement is then applied to the outer surface of the thermoplastic core tube to form an interstitial layer of metal reinforcement. As is clear from the description below, the term "space" here refers to a small opening, ie, a space, that is formed when a metal reinforcing material is applied to the outer surface of the core tube by braiding, spiral winding, or the like. Next, the metal reinforcing material layer is heated by induction heating to locally heat and soften a limited portion of the outer surface of the core tube that is in contact with the layer (i.e., the portion covered by the metal reinforcing material layer). . This softened portion of the outer surface of the core tube then migrates between the reinforcement layers. Thereafter, upon cooling of the transitioned portion of the core tube, a uniform, ie, solvent-free, mechanical interlock is produced between the core tube and the reinforcement. Such an improved interlock, which serves to maintain the integrity of the composite structure, has the advantage of providing torsion resistance and better performance under hydraulic shock conditions. Additionally, if the core tube is coated with a thermoplastic cover material that is compatible with the material, the heat from the extruded cover will soften the transition area, thus reducing the cover and the transition area. A fusion between them is caused.

Subsequently, the configuration, effects, etc. of the present invention will be described in detail below. From this detailed description, objects and advantages of the invention, other than those set forth above, will become apparent.

The invention will first be described with respect to representative embodiments illustrated in the accompanying drawings.

In the perspective view shown in FIG.
It generally refers to a hose consisting of three commonly used ingredients.

Advantageously, the reinforcement 12 is applied to the core tube by a braiding or spiral winding machine, generally designated 14 (see FIG. 3). In the attached schematic diagram (see Figure 2), between the number 1
The reinforcing material 12 is manufactured by means of a metal wire 15 on a braiding or winding machine according to the method used to form the reinforcing material 6. When using a braiding machine, one metal wire is crossed over the other, and when using a spiral winding machine, each set of metal wires is wrapped onto the same layer. In any case, among the majority = 16
There is no difference in the fact that it is created.

As shown in FIG. 3, after the reinforced core tube 11 exits the braiding machine 14, it passes through a conventional heating coil, indicated at 17. The heating coil 17 first heats the reinforcing material 12 (see FIG. 2) made of metal wire, and then the heated reinforcing material 12
locally heats a limited portion of the outer surface of the core tube 11 located below and softens it. This softenable core tube transitions between metal reinforcements 12 and 16, as explained below.

Referring to FIG. 4 (only one metal wire layer is shown for clarity and ease of understanding), a number of protrusions 18 protrude from the core tube 11 and these protrusions provide further reinforcement. It will be seen that there is interleaving between the various knits or ribbons of material layer 12. As can be seen in FIG. 5, the knitted fabric (represented generally by the number 15) is made up of a number of strands 19...the protrusions 18 are...
This is what was previously called the transition section... This fifth
If you study the diagram, you will notice that each reinforcement section is usually 2
It will be appreciated that there will be one metal wire layer, ie, strand 19, and that this is independent of using either a braid or a spiral winding. Here, "two metal wire layers" means that when a braid is used, one set of metal wires is overlapped with another set of metal wires, so that two metal wire layers are overlapped. This also means that when spiral winding is used, two sets of metal wires with different winding directions are overlapped to form two overlapping metal wire layers. That is, it means that the cross section of the metal wire reinforcing material has a two-layer structure.
Note that this cross-sectional structure is shown in the fifth section, which is a plan view of the hose.
This cannot be recognized in the diagram.

In Figure 6, the reinforced core tube 11
It is shown with a cover 13 over it. Typically, the cover is extruded over the reinforcing core tube at a location physically remote from where the braiding or spiral wrapping was performed. The heating (carried out in step 17) may be carried out immediately following the braiding or spiral winding, or may be carried out after a period of time but consistently, or else as the case may be. , may be performed at physically separate locations. Furthermore, the heating step may be performed after or simultaneously with the installation of the cover over the core tube. Furthermore, a plurality of reinforcing members may be used, as shown at 12 and 112 in FIG. In such a case, the core tube may be subjected to a first section and heated as described above, thus forming the protrusion 1.
8, then apply a film or sheet of thermoplastic material, designated 111, and add another braided or spiral wound section (second reinforcement section), designated 112, to the previous film or sheet. and further heating is performed to form protrusions 118. Note that in such cases, the thermoplastic film or sheet 111 must be compatible with the core tube material (i.e., the film or sheet 111 must be compatible with the core tube material).
1 must be able to fuse with the core tube material).

In FIG. 7, the top and bottom of the strand 19 are particularly selected and shown enlarged. The number 18 indicates what mechanical interlock exists in combination with the covering cover 13. As mentioned above, if the core tube material and the cover material are compatible, these two materials can be fused together. A variety of such materials may be used in practicing the present invention. For example, the thermoplastic material used for the core tube 11 may be a polyester elastomer, such as DuPont de Nemours & Company.
It may be “Hytrel” manufactured by Inc.). This same material may be used for the cover, or alternatively, polyurethane or polyamide materials may be used for either the core tube or the cover, or both, as the case may be.

Next, the present invention will be explained by the following examples.

Example 1 The core tube has a nominal diameter of 1/2 inch and
It was a thermoplastic material (Hytrel) with a wall thickness of 0.050 inches. In this core tube, 1.385
12 mil brass coated steel wire (7 strands per braid) was braided using lead wires. The core tube thus braided (with a relatively fine gap) was passed through a Lepel 2.5kW induction heating machine operating at a frequency of approximately 300 to 400kHz, power setting of 95, and grid setting of 67. . The coil design was 10 1/2 turns (wound with a 1 1/4 inch inner diameter). The coil itself is a copper tube (3/16 inch in diameter) coated with "Teflon" (trademark of DuPont), with an internal diameter of 80
It was cooled in a closed circuit with deionized water at 〓 (approximately 26.7℃). The two-component hose was guided through the induction heater at a feed rate of 8 feet per minute and internally pressurized with air (approximately 30 psi pressure) with a slow release of air. Following removal of the reinforcing tube from the induction heater, the tube was air cooled and covered with a polyurethane cover having a wall thickness of 0.030 inches and a hardness of 80 Å. Cooling resulted in a well bonded composite hose structure. The structure had sufficient flexibility, did not twist when bent, and had good performance under hydraulic impact conditions, ie, SAEJ517. In addition to being lightweight, this hose was economical in terms of manufacturing costs, and had performance that far exceeded the performance required by SAE100R1. Furthermore, since interlocking has been achieved, there is a "flare formation", i.e., when the resulting hose is cut for connection, the cut steel wire radiates outward (this causes the installation of the fitting or connector). could be significantly advantageously prevented. Fittings are typically configured to attach to the outside diameter of the hose, so it is clear that any flare would preclude easy assembly of the hose.

Example 2 The procedure described in Example 1 above was repeated except that a Hytrel thermoplastic core tube was provided having a nominal 3/8 inch diameter and a wall thickness of 0.045 inch. The completed hose in this example is 0.385
It had an inner diameter of inch and an outer diameter of 0.580 inch. The same type of reinforcement as in Example 1 above was applied. Interlocking was achieved through the use of the same type of induction heater as in Example 1 above. however,
In this example, process conditions were applied such as a feed rate of 14 ft/min, an internal pressure of 50 psi (gently releasing air), a power setting of 100, and a grid setting of 64 to achieve this engagement. . Thereafter, the thickness is determined as described in Example 1 above.
Covered with 0.030 inch cover. The composite hose obtained in this example was equivalent to that of Example 1 and was fully satisfactory.

As previously discussed, a variety of materials of construction may be used in practicing the invention. More specifically, the present invention can be applied to all polymers that soften and melt when heated. Suitable core and cover materials include thermoplastic materials such as nylon 11, nylon 12, polyester (manufactured by DuPont)
Hytrel), polyurethane, and thermally crosslinkable polymers that melt upon heating and subsequently form crosslinks.

According to the invention, a core tube may be formed from one or more layers fused together. For example, the innermost layer of the core tube may be prepared from "Hytrel" (supra) to impart chemical resistance to it, and the outer layer (second
(layer) may be prepared from polyurethane to impart improved flexibility to the tube and to achieve material cost savings.

Types of reinforcement can include, for example, spiral wraps, braids and other suitable types, and materials of construction can include, for example, brass-coated steel wires as mentioned above or other suitable types. Mention may be made of metal wires which impart the desired strength to the hose and which can be heated by induction heating or other heating means, for example resistive heating with contact electrodes or the like. In any case, heating is limited to the area adjacent to the outer surface of the core tube (or otherwise the film or sheet if multiple reinforcements are used) in order to form protrusions in relation to the spaces between the reinforcements. It is advantageous to carry out If this heating is achieved by induction heating, the frequency can be advantageously increased to 60
Hz to about 1 MHz (in contrast, if dielectric heating is used, frequencies from 10 MHz to the microwave range must be used).

The degree of heating of the reinforcement layer can advantageously be adjusted depending on the coil design, the speed of the hose passing through the coil, the power level of the heater and the frequency of operation. The inventors have found that it is particularly advantageous to be able to adjust the amount of heat reaching the core tube from metal wires or other reinforcements by guiding a cooling fluid into the core tube. If you do this,
At the same time, another advantage is obtained that the core tube can be internally supported, thereby preventing the formation of dents in the tube. As mentioned earlier, this involves charging compressed air into the core tube and maintaining its pressure (by constricting the downstream end of the core tube so that only a limited amount of the compressed air is "released"). This can be achieved by: This results in a slight flow of compressed air to carry away excess heat. If this were not done, local distortion of the core tube would occur, thus resulting in a defective final product.

The product produced according to the invention has a homogeneous core tube, which advantageously interlocks with a reinforcement layer. Here, the term "homogeneous" refers to the type of interlock traditionally achieved through the use of special layers, especially through the use of solvents (which in normal cases leave at least traces so that the core tube is not homogeneous). The mesh that has been
It is used to distinguish between the term and that of the present invention.

According to the method of the invention, a hose with a thermoplastic core tube can be produced that is economical to manufacture and highly reliable in use. Although this method uses a single layer core tube, it is unnecessary to use a tie or adhesive layer as in that of the prior art. This single-layer core tube not only minimizes equipment and handling problems that are unavoidable with hoses using bonded or bonded layers, but also allows the core tube to be reprocessed if necessary. It also makes it possible. In fact, if the core tube has an additional layer of different material,
Conventionally, its reprocessing was impossible. Furthermore, according to the method of the invention, it is unnecessary to complain about incomplete bonding between the bonding layer and the core tube, and thus a more reliable hose can be obtained. Incidentally, if there were any unbonded parts between the core tube and the additional layer, even if they were very small, this would inevitably lead to failure of the hose. This is because these unbonded areas have expanded during the flexing, shock and temperature cycling that the hose is exposed to during its use.

Furthermore, according to the method of the present invention, the core tube can be heated using an induction heater in a direction that only locally heats the surface portion of the tube that is in contact with the metal reinforcing material. Due to this heating method, it is possible to locally heat only the surface of the core tube without significantly heating the entire core tube, and therefore to obtain a good bond between the core tube and the metal reinforcement. can. At this time, there is of course no deterioration in the properties of the polymeric material constituting the tube or loss in dimensional stability, which could occur if the entire core tube was heated. Furthermore, because of this localized heating, the hose can be subjected to a wider range of operating temperatures (service temperature) compared to conventional hoses (here, we will focus on the factors that reduce the temperature rating of the hose). (because it does not use a bonding layer with a low melting temperature). Furthermore, according to the method of the present invention, since only the surface portion of the core tube is locally heated, a hose can be manufactured without using a mandrel.

Although the invention has been described in detail with particular reference to preferred embodiments thereof, it will be understood that various changes may be made in detail without departing from the spirit and scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a fragmentary perspective view of the hose of the present invention, FIG. 2 is a schematic diagram showing a part of a machine for coating the core tube with a reinforcing material layer, and FIG. 3 is a partial perspective view of the hose of the present invention. FIG. 4 is a cross-sectional view showing a part of a hose manufactured according to the method of the present invention, and FIG. 5 is a schematic diagram of the apparatus used in carrying out the invention. FIG. 6th plan view showing the state of the external surface of
The figure is a cross-sectional view of a hose with a cover on top, Figure 7 is an enlarged cross-sectional view of the hose shown in Figure 6, and Figure 8 is a cross-sectional view of a hose with double reinforcing material layers. It is a diagram. In the figure, 10 is a hose, 11 is a core tube, 1
2 is a reinforcing material, 13 is a cover, 14 is a braiding machine or spiral winding machine, 15 is a metal wire, 16 is a spacer,
17 is a heating coil, 18 is a protrusion (transition part), 1
9 is a strand, 111 is a film or sheet of thermoplastic material, 112 is a second reinforcement, and 11
8 is a protrusion.

Claims (1)

[Claims] 1. A method for continuously manufacturing a hose, comprising the following steps: forming a core tube made of a thermoplastic material; applying a metal reinforcing material to the outer surface of the core tube to form a metal wall with a gap; forming a reinforcing material layer; heating the metal reinforcing material layer by induction heating to locally heat and soften a limited portion of the outer surface of the core tube that is in contact with the layer; transferring between the layers of metal reinforcement; cooling a limited portion of the outer surface of the core tube to mechanically interlock the core tube and the metal reinforcement; 1. A continuous method for manufacturing a hose, comprising: extruding a cover made of material and fusing it thereto. 2. The manufacturing method according to claim 1, wherein the induction heating is performed at a frequency included in the range of 60 Hz to 1 MHz.