JPS6034612Y2 - Sealing plunger for generally cylindrical cartridges - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The contents of certain cartridges used for sealing and gap filling purposes are susceptible to activation by moisture or to deterioration on contact with air or moisture, and therefore the plunger and cylinder of the cartridge It has been recognized in the art for many years that a good seal with the wall is important.

This sealing problem is further complicated by the thermal expansion and contraction of the contents, which requires a slightly movable plunger.

Although many proposals have been made for ways to create an improved seal between the plunger and the cartridge, all of them have problems with cost, assembly, and compatibility with existing equipment or problems with achieving a satisfactory seal. There is a problem that cannot be established.

The present invention achieves improved sealing at minimal cost and without the need for additional parts, additional assembly steps, or substantial modifications to current equipment for loading and dispensing cartridges. means recognition of how to create different seals for plungers.

The invention aims to obtain the best possible sealing with the least disruption of the status quo for the lowest possible cost.

The sealed plunger of the present invention has a generally cup-shaped body molded from a resin material sufficiently rigid to provide structural support for the plunger.

a sealing material is molded from a resinous material substantially softer and more resilient than the resinous material of the body, and is connected to the body; and the body is annular and spaced a short distance from the inner surface of the cartridge. a wall, and the sealing material extends around an outer surface of the annular wall, the annular wall compressing the sealing material into intimate contact with the inner surface of the cartridge when the plunger is within the cartridge. .

The sealing material preferably also has an annular ridge pressed against the inner surface of the cartridge, and the sealing material covers the trailing edge of the annular wall of the body of the plunger and is initially inserted into the cartridge. The cartridge may also extend over the trailing edge of the cartridge when inserted into the cartridge.

Alternatively, the annular wall of the plunger can be in close engagement directly with the inner surface of the cartridge, and the sealing material can be bonded to the annular wall, and the annular wall of the plunger can be first inserted into the cartridge. At times, it may extend to surround and engage both the inner and outer surfaces of the rear region of the cartridge.

The plunger 10 shown in FIG. 1 of the accompanying drawings has a cup-shaped portion 11 which is molded from a relatively rigid resin material and serves as a structural support for the plunger.

The body 11 includes a plunger 1 in a generally cylindrical cartridge.
0 has a generally cylindrical annular wall 12 sized to be a short distance from the inner surface of the cartridge when inserted.

The material of body 11 can be any of a few commonly known resinous materials that are relatively stiff or hard, such as high density polyethylene or polypropylene having a hardness of approximately 60-70 Shore D.

Surrounding the outer surface of the annular wall 12 is a sealing material 13, which is also a molded resin, but is preferably substantially softer and more resilient than the resin of the body 11.

Examples of resins suitable for the sealing material 13 include ethylene.
These include vinyl acetate copolymers, low density polyethylene, thermoplastic rubbers, plasticized polyvinyl chloride, and ethylene-ethyl acrylate copolymers.

Preferably, the sealing material 13 is formed with an annular ridge 14 extending along the outer circumference of the plunger 10 and the ridge 1
4 is compressed into intimate contact with the inner surface of the cartridge by the outward pressure exerted by wall 12.

The pressure on deforms and flattens the ridges 14 to provide an excellent seal □, and the compressibility and deformability of the sealing material 13 is achieved by forming the plunger 10 of a single resin material. Allows for a better seal than is possible.

Preferably, the sealing material 13 is attached to the body 11 in the form of a thickened ring 16 that helps attach the sealing material 13 to the body 11.
1 and extends around the trailing edge 15 of 1.

The rear edge 15 of the body 11 can also be formed with an inwardly facing bevel 17, as shown in FIG. In addition, a ring can surround the inner periphery of the edge 15 and extend up to an interlocking part 18 which engages the bevel 17.

The embodiment of FIG. 2 shows sealing material 1 pressed against cartridge wall 20 with sufficient pressure to flatten ridges 14.
3 is also shown.

The embodiment of FIG. 2 extends rearwardly from the ring 16;
Also shown is the addition of a peripheral edge 21 surrounding the trailing edge 22 of the wall 20 so as to terminate in a free edge 23 meeting the outer surface of the wall 20.

The peripheral edge 21 is shaped to press against both the inner and outer surfaces of the wall 2'0 at the rear end of the cartridge to provide an auxiliary seal.

The material 13 is sufficiently flexible to allow the peripheral edge 21 to move the plunger as the contents of the cartridge expand and contract, and to remain free when the plunger is advanced to deliver the contents of the cartridge. Edge 23 is flexible enough to go around trailing edge 22 and follow body 11 into the cartridge.

An alternative sealing arrangement is shown in FIG. 3, in which the annular wall 12 engages and is in direct pressure contact with the cartridge wall 20, and the sealing material 13 is in a rear region 24 of the wall 12. The free edge 2 is connected and as described above with respect to FIG.
3 and surrounding the trailing edge 22 of the wall 20.

Preferably, a plurality of annular ridges 25 are formed so that wall 20
It is designed to be pressed against the inner surface of the

Peripheral edge 21 provides an auxiliary seal to protect the contents of the cartridge before use, and peripheral edge 21 and free edge 23 extend around trailing edge 22 of wall 20 and along body 11 as the plunger is advanced. It is flexible enough to enter the cartridge.

Those skilled in the art will recognize the variety of materials and configurations possible in creating improved seals in accordance with the present invention by using two different resin materials with different hardnesses.

The sealing ridge, periphery, and form of anchorage that helps attach the two resin materials to each other can be varied considerably once the basic principles of the invention are understood.

[Brief explanation of drawings]

FIG. 1 is a half cross-sectional view and half an elevation view of a preferred embodiment of the plunger of the present invention, and FIGS. 2 and 3 are partial cross-sectional views of other preferred embodiments of the plunger of the present invention. be. 10..."On the sealed plunger 11..."
- "Generally cup-shaped body", 12... "annular wall", 13... "sealing material".

Claims (1)

[Claims for Utility Model Registration] 1. A sealed plunger for a generally cylindrical cartridge, having a generally cup-shaped body molded from a resin material sufficiently rigid to provide structural support for the plunger. b. the body has an annular wall having a generally cylindrical outer surface having a substantially shaped area evenly spaced from the inner surface of the cartridge when the plunger is in the cartridge; C. a sealing material molded from a resinous material substantially softer and more resilient than said resinous material and bonded to said body; d said sealing material surrounding said entire outer surface of said annular wall; e the sealing material is in a resin-to-resin bond with the annular wall; and f the annular wall extends the sealing material into the cartridge when the plunger is in the cartridge. A sealing plunger for a generally cylindrical cartridge, characterized in that the sealing material is compressed into intimate contact with the inner surface of the cartridge to conform to the inner surface of the ridge. 2. Utility Model Registration The plunger according to claim 1, wherein the sealing material extends radially inward from the outer surface of the annular wall to cover the rear end of the annular wall. Sealed plunger. 3. In the plunger according to claim 2, when the sealing material is initially inserted into the cartridge, the sealing material surrounds the rear end of the cartridge and extends axially rearward and radially. The sealed plunger is characterized in that it extends outwardly. 4 Utility Model Registration In the plunger according to claim 1, the sealing material is formed with an annular ridge that is pressed against the inner surface, and the sealing material extends to cover the rear edge of the annular wall. Said sealed plunger characterized by: 5 Utility Model Registration In the plunger according to claim 1, when the plunger is initially inserted into the cartridge, the sealing material surrounds the rear end of the cartridge and extends axially rearward and radially. The sealed plunger is characterized in that it extends outwardly.