JPS60227064A - Radial lip seal and production unit thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to radial type fluid seals and apparatus for making them.
Preferably, it is equipped with a dustproof lip and is made of polytetrafluoroethylene (hereinafter referred to as Mizuhiki 11113 I) T F
A resilient radial lip seal having a bonded wear insert made in combination with a bonded wear insert made by E and an apparatus for forming the same are described.

[Background Art] )) T r: [E is a dynamic sealing material that is innovative in many respects. It has a low coefficient of friction, so it slides easily, generates very little heat, especially when used in dry conditions, and is abrasion resistant, so it does not wear out easily. Furthermore, 1) T [
E is non-porous, stable in the sense that it does not react chemically or thermally, and is not permeable to liquids, solvents,
Almost unaffected by oil etc.

In addition to the aforementioned advantages, it is elastic over a very wide temperature range.

However, the negative side of P T F E is that it has two properties that make it an extremely difficult material to create fluid seals that can take advantage of the excellent properties mentioned above. First, P
T F E is that it cannot be molded into various shapes as is possible with common elastic materials and plastics, such as thermoplastics and heat-set plastics.

In practice, PTFE is consolidated and sintered from the powder state in which it is manufactured, much like making powder metal parts. Even more important is the fact that it does not have a liquid phase like most plastics, but sublimes directly from the solid state to the gaseous state above temperatures of >288°C (550F).

Second, PTFE does not easily soften and is not as elastic as the common materials from which seals are made, such as nitrile rubber, polyacrylic rubber, silicone rubber, etc. Easily elastic, so-called rubber' conforms to and makes intimate contact with whatever surface it is pressed against. As such, the rubber can provide a positive seal that prevents the passage of fluids at the contact surfaces. On the other hand, PTFE is stiff and tends to form bridges at elevated points on the suppressed surface. This will also create a small groove through which fluid will migrate in static conditions with no relative movement aJ between the seal and the sealing surface.

The conditions described above indicate that even if a seal can be made with materials that do not make intimate contact, some type of mechanism must be included to direct any migrating or leaking fluid back to the oil side of the seal. ing. This is facilitated by making the seal hydrodynamic, for example by providing a hydrodynamic flute in the sealing lip of the seal.

As mentioned above, what is important is the fact that P T F E has no appreciable liquid phase. Therefore, it does not flow into molds of various shapes as most elastic materials do. Instead, U.S. Pat. No. 3,857,156, U.S. Pat. No. 3,929,341, U.S. Pat.
J0 or (
or) must not be pressed. In the aforementioned patent, P T F E with a hydrodynamic flute
The manufactured sealing lip is formed by turning the entire part or by turning and pressing with a die before assembly into the seal. Of course, turning and heading operations are relatively complex and expensive. Another attempt in the prior art is to use a radial lip seal made of elastic material and PTFE in the sealing lip, as shown in German Offenlegungsschrift No. 2435675.
It is formed by combining a wear surface made of steel. However, the latter technique does not suggest forming a PTFE wear insert with a hydrodynamic wear surface.

As can be seen from the foregoing description, in the prior art, the wear insert can be economically and easily produced by forming a hydrodynamic surface on its F with a simple molding process.
It has not been possible to satisfactorily and economically produce fluid seals containing FE wear inserts.

Also, such prior art seals do not have anti-corrosion lips, and such seals will quickly wear out the shaft.

[Disclosure of the Invention] The present invention provides a fluid seal employing abrasion indentation of a seal lip using a solid, deformable, but non-moldable P'rFE material, and a process for forming the same. The present invention provides an apparatus which overcomes various disadvantages associated with previously known seals and processes. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fluid seal having a PTFE insert with a fluted hydrodynamic surface having good wear resistance, and an apparatus for forming the fluid seal.

Broadly speaking, in accordance with the spirit and scope of the present invention, a solid, deformable, non-mouldable material having a hydrodynamic surface located on the sealing lip and bonded thereto by heat and pressure forming. A new and improved apparatus for forming a resilient radial lip with a wear insert material made of PTFE and a seal made thereby is provided. In some embodiments, the device has a hydrodynamic flute shape in place and incorporates a preheated surface that forms a portion of the mold cavity of the device during the molding operation. The step of positioning the seal case member coated with an appropriate adhesive on the lower mold core, and so that the fluted surface is positioned close to the predetermined position where it is installed.
Suitable for use on the lower mold core. In this method, the device is placed adjacent to a closed and sintered PTFE ring, and the elastic, deformable, non-moldable ring and seal case member are heated and pressurized. The above-mentioned pressurization forces the sections of the deformable annular material into a recessed fluted surface on one side of the mold with a vinegar solution generated when the elastic material is cured. the deformable, non-moldable annular member is pressed into place sufficiently so that a protrusion corresponding generally to the recessed surface of the mold is formed on the deformable, non-moldable annular member. The method of using this device is to harden the elastic annular material and the adhesive, and the molded elastic annular material is tightly attached to the seal case member in a state of 1[- and deformable].
To ensure the formation of an integrated radial lip seal that adheres the flexible annular to the molded bullet f1 annular, the pressure and temperature are maintained for a predetermined period of time, and then the integrated radial The lip seal can be removed from the mold cavity.

Additionally, the present invention may include a fluid-mechanical (2) elastic radial lip seal in which the seal body is bonded to the resilient seal body at the seal lip, in which case the seal body is bonded to the resilient seal body. An auxiliary dust-proof lip spaced axially from 11 and made to engage with 1F is angularly formed and dimensioned as such.

[Example] FIG. 1 is a cross-sectional view showing the relative positions of the parts 4 of a seal according to the present invention, which are placed in a compression mold, which is the housing 4 of the present invention, before the molding operation. With the exceptions noted below, the compression molding used herein is performed in a standard manner on conventional components. Accordingly, the heat, pressure d3 and time required for the process will vary according to methods well known in the art. The first molding phase or lower mold member 10, which acts as a core, is pressed (
(not shown) is held in place on the lower platen. Similarly, the upper mold or ring 14 is held in place on the upper platen of the brace (not shown) by a centrally located bolt 16.

The first mold member 10 has a peripheral shoulder 18;
Its function is to position a sealing case 20 made of a suitable metallic material and coated with a suitable adhesive in a conventional manner. Seal case 20 has a cylindrical outer portion and an annular flange portion extending radially inwardly therefrom.

The mold core 10 according to this embodiment has a mold core 10 that forms most of the inner surface of the seal and a fluted surface 23 on the conical side surface of the first conical portion of the first molding member 10. It includes a circumferential outer protrusion 24 located at the end. A sintered molded, one-knee, one-knee wear insert ring 26 is expanded and fitted over the protrusion 24, which has an inner diameter J and an outer diameter. Like the case 20, it is pre-treated with a suitable adhesive by a tf method, such as by brushing, rolling, gluing, or spraying.The mold preferably seals the metal case 20 in place. The elastomer is preheated to the curing temperature of the elastomeric agent used.Also, the protrusions 24 enhance proper positioning of the wear insert 1-.Such protrusions are not found in conventional compression molded parts.

Further, a shoulder portion 25 for an insert is provided below the fluted surface 23. This insert shoulder portion 25 will be explained later in 1.
This prevents the wear insert 26 from sliding down from a predetermined position due to the fluidized elastic material during the molding process. To explain ``
1. Inserts 2.
6 must be spread out to be positioned in close proximity to the hydrodynamic fluted surface 23 and over the protrusion 24. The mold 10 is formed with a four-pronged protrusion 24 located at the outer end of the fluted surface 23 in the axial direction. The initial shape of the wear insert is a flat washer inside the cylinder. During positioning, without substantially changing the outer diameter, the wear insert 26 expands its inner diameter, thereby deflecting what was originally a flat washer and bringing it closer to the hydrodynamically shaped surface 23 of the mold core 10. Then, as shown in FIG. 1, the whole becomes conical. If the wear inlet 26 is further expanded, it will cover the fluted surface 23 of the mold core 10.

The hydrodynamic surface 23 is shown in FIG. 1 as a helical groove in the -h direction. For purposes of illustration, surfaces of this shape will be used throughout the description. The hydrodynamic shape pressed in the mold can be of any shape, whether left-handed, right-handed, unidirectional, or various shapes such as double-threaded flutes. However, the present invention is not limited to the specific shape shown here.If a mechanical flute has a discontinuity in the circumferential direction, as in the case of a one-ridge phenomenon, the shaft may become stationary. Sometimes leaks occur.

Continuing to refer to FIG. 1, an uncured elastic material 27 is positioned around the taper 28a of the second conical portion of the lower mold 10 and rests near the wear insert 26. The prepared elastic material is attached to the upper mold ring 1 of the second mold member.
4 is larger than the remaining volume of the cavity formed inside the mold when it is closed onto the lower core 10. As is well known in the art, this difference generates extremely high hydrostatic pressures as the elastic material 21 heats up inside the closed mold and becomes semi-liquid. This semi-liquid elastic material always flows to every corner of the mold cavity when the mold is in the closed position shown in FIG. It is squeezed between the male taper 28a and the female taper 28b of the ring 14. These tapers are very accurately machined to fit perfectly into each other. By being generally within 4 degrees of O as measured relative to the base of mold member 10 or 14, relative axial movement between the molds as the molds are closed is such that surface 28b is aligned with surface 28a. The radial closure J on approach is greater. This difference in closure speed creates extremely high pressures inside the mold as the passage between surfaces 28a and 28b is closed to essentially zero.In fact, This pressure is sufficient to permanently deform or force the P T F E wear insert 26 into tight engagement with the hydrodynamically shaped surface 23 of the mold core 10 in place by the insert shoulder 25 . This pressure was found to be of a significant magnitude and maintained throughout the curing cycle of the elastic material.

The profile 30 of the part yJ ring 4 forms the outer shape of the sealing member. The annular bottom surface or closing surface 32 is a tapered surface 28
Provision is made to clamp the sealing metal case member 20 at its radial annular flange against the mold cavity 10 shortly before a and 28b are brought together. In that way, excess semi-liquid elastomeric material is prevented from escaping in the seal metal section before final pressure is applied. To finally close the tapered surfaces 28a and 28b, the unhardened seals 1 to 20 must be slightly depressed or pushed by the closing surface 32 of the mold ring 14. .

FIG. 2 shows the mold ring 14 fully closed against the mold core 10 and clamping the sheet metal 20 at position 40. At this stage the elastic material 27 (seen in Figure 1)
becomes semi-liquid and completely fills the mold cavity to create the new shape, as shown at 42.

Internal pressure is built up inside the mold, and the P'I-F E wear inlet 26 is pressed against the hydrodynamic flutes 1 to 1 23 of the mold core 10 at position 44. The so-called "hat" 4G of the seal is non-functional in that it is not part of the final seal shape, as shown in Figures 3-5). Regarding the molding of the elastic material forming the shell 1-, it simply fills the part between the mold members that do not contact each other, and the narrowing part which is the interface between the male taper 28a and the female taper 28b shown in FIG. This ensures complete mold closure between position 40 and J-Pa 28.

The cavity 48 of the ring is closed as shown in FIG. 2 to accommodate the extra elastic 'JA27' that does not fit the mold.
It was established in Redundant items are those that jump out and are known as 50. There should be enough elastic material 27 to fill the mold cavity, but with some protrusion to ensure that the necessary pressure is generated to press the wear inserts 1-26. is important.

Type 1, shown in FIG. 2, is held open and closed maintaining heat and pressure against the elastic material 27. Heat and pressure create chemical cross-bonds within the elastic lubricant. The adhesive is supplied to the metal case 20 and the P T FE wear in one notebook 26 . This cross-bonding allows the elastic material and adhesive to harden, ensuring that all parts adhere to each other and remain integral during removal from the mold.

FIG. 3 is a sectional view showing details of the seal after it has been removed from the mold. The elastic body portion of the seal is bonded to the sheet metal case 20 at 60 and to a stamped PTFE wear insert having a fluted surface 44 at 62. The excess -Im is removed from the seal body portion 42.

This resection line is I) T F E in J ＼ It does not remove much of the reet, or it can be used as a resection line (a small amount and is substantially relatively expensive r') T 1
1'E In order to avoid waste of materials, the shape of the in-4)-1- is made to be sufficient even if it is only needed once.

The spring groove 64 is optional and depends on the ultimate application for which the seal is to be used. If the position of the spring groove 64 is 1 tithe
The use of the garter spring 70 in a sealed seal increases the radial pressure of the seal lip on the shaft 720 as shown in FIG. Increased radial hydraulic pressure increases radial friction and wear, which may be undesirable for the application. On the other hand, the wear-in hydrodynamic shape 44 tends to wall the shaft 12 and increase the hydrodynamic efficiency of the seal.

FIG. 5 is a cross-sectional view of another embodiment similar to that shown in FIG. lip 74
is formed. In certain applications where the working environment is particularly dusty, this supplemental dust lip 14 can greatly extend the useful life of the seal. To be more precise,
This greatly extends the life of the other half of the seal, the shaft.

If you pull this auxiliary dustproof lip 74, the dust will be removed by PTF.
Try to enter the area between the wear insert 26 and the rotating shaft 11. The resulting mechanical wear process is called PT.
Since the FE wear insert 26 is softer than the metal shaft 72 and dust particles, such dust particles are bitten into it. Therefore, dirt particles are buried in the PTFEFJ wear inserts 1 to 26 and are removed. When debris is removed in this way, it forms the surface of the sealing lip.

Most trash contains sand particles, which are composed of a significant number of quartz crystals. Of course, since quartz is harder than steel, the wear insert 26 turns into a piece of sandpepper and rapidly erodes the steel shaft 72.

Particles eroded from the shaft also become embedded in the P, TFE wear insert, accelerating shaft wear.
That will happen. Garbage is P'r l:' E 11! All of the above occurs during operation, as the wear insert is stationary and its sharp corners slide on the rotating shaft. Unprotected PTF without lip 74
EJ! ! The wear insert 26 also does not wear, but the exposed shirt 1- wears to the point where the seal can no longer function on the damaged shaft surface. Therefore, the dust lip device 74 is an important part of the seal, especially in relation to the sealing lip of the wear-in-four note 26, since it covers up the associated drawbacks caused by the absence of this dust lip.

From the foregoing description, it is clear that the present invention can be used to manufacture seals and seals having desirable wear resistance.

Although the invention has been described in connection with preferred embodiments, it is not intended to be limited to the specific forms described, but on the contrary, within the spirit and scope of the invention as defined by the appended claims. Other alternatives, modifications, and equivalents may also be available online.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the compression mold of the apparatus of the invention in an open position with the individual members of the radial lip seal according to the invention in the position before the molding operation; FIG. 2 shows the compression mold of the apparatus in the closed position during the molding operation; 3 is a partial sectional view of the seal according to the invention as it has been removed from the mold, showing the trim line; FIG. 4 is a section of the seal according to the invention mounted on a shaft. Cross-Sectional View FIG. 5 is a cross-sectional view of another embodiment of the present invention in which the body of sealing elastic material is extended to form an auxiliary dust lip. In the drawings, 10...First mold member 14...Second mold member 20...Seal case member 23...Fluted surface 24...Protrusion 25... Insert 1 - Skin part 26... (PTFE) Wear insert 27... Elastic material (uncured) 28a... Second conical portion 28b... Conical concave surface 30... Second molding Ring part of mold member (?I-U phase

Claims (1)

[Scope of Claims] (1) A rigid case member, an elastic seal body part extending from the case member and fixed to the member, and a main body adhered to the seal body part at the free end of the elastic seal body part. a wear insert forming a sealing lip, the wear insert being a relatively thin annular member of deformable but cold PTFE, the main sealing lip being a a top portion configured to fit in interference relationship with the wear insert, and comprising two radially converging surfaces of the wear insert, said wear insert having a hydrodynamic characterized by having a stamped flute of design to make circumferentially discontinuous contact with the mating shaft surfaces, and to force fluid to move from one side of the apex to the other by rotation of the shaft; Elastic radial lip seal for fluids. (2) A fluid elastic radial lip seal according to claim 1, wherein the hydrodynamic design is unidirectional, consisting of a helical groove. (3) In the seal according to claim 1, the elastic seal body portion includes a portion that extends axially inwardly and angularly away from the main seal lip and forms an auxiliary dust-proof lip. An elastic radial lip seal for fluids comprising: (4) A wear-resistant insert made of a non-moldable annular PTFE material is provided at the part that contacts the shaft, and around it, an annular part of an elastic material and a cylindrical side for surrounding and supporting the insert and the annular part of the elastic material. A device for forming a radial lip seal having a hydrodynamic flute on the shaft-contacting side of the insert and the insert, said device acting as a tang forming a through-bore portion for the shaft of the seal. a first mold member; a second mold member for cooperating with said first mold member to form said seal; 40. Example: said first mold member forms a cylindrical N portion of said case member; a generally disc-shaped portion for receiving the annular flange portion and seating the annular flange portion; a first conical portion having a generally truncated conical shape protruding malely from the upper portion of the disc at approximately the center of the disc-shaped portion; a second conical portion having a diameter generally smaller than that of the conical portion and further extending in the axial direction from the first conical portion; and a conical side surface of the first conical portion close to the second conical portion. a circumferentially continuous groove portion corresponding to the shape of the hydrodynamic flute; and a conical shape of the first conical portion between the groove portion and the disc-shaped portion; The second mold member has an insert shoulder portion having a larger diameter than the groove portion provided on the side surface, and the second mold member has an annular ring portion for tightening the annular flange portion of the case member against the disc-shaped portion. , a conical concave portion corresponding to the second conical portion that finally comes into close contact with each other when the first and second mold members are combined; (5) In the device according to item 4, the annular flange portion of the case member is fastened by the first and second mold members; After application, the second conical portion and the conical concave portion are brought into close contact with each other. (6) In the device according to item 5, a disc-shaped protrusion protrudes radially outward from the first conical end at the boundary between the first and second conical parts. A device having parts. (1) The device according to any one of Items 4, 5, and 6 above, wherein the continuous groove portion is unidirectionally threaded.