DE8710233U1 - Cartridge piston - Google Patents

Abstract

In order to press a viscous mass out of a cylindrical cartridge (10), a cartridge piston is used which has an integral piston body (14) with a sleeve (15) running parallel to the cartridge wall (11). If the plastic mass contained in the cartridge (10) inclines towards bonding the cartridge piston in place, there is the risk that the piston will be moved into an oblique position when being pressed forward. In order to stiffen the piston, a reinforcement ring (25) is inserted in a clamping fashion into the sleeve (15). The stiffness of the reinforcement ring (25) is greater than that of the piston body (14). The reinforcing body stiffens the piston against compression. Although the piston is, as a whole, rigid, the ability of the sleeve (15) to fit tightly against the cartridge wall (11) is preserved. <IMAGE>

Description

Cartridge piston

The invention relates to a cartridge piston according to the preamble of claim 1.

It is known to store viscous and sticky masses in cylindrical cartridges and to press these masses out of an opening at the front end of the cartridge using a pistol-like squeezing tool. In the rear area of the cartridge there is a piston _t which consists of a one-piece plastic part of medium hardness and has a jacket provided with wiper lips which sweep along the inner wall of the cartridge when the piston is pushed forward. The mass in the cartridge is pushed forward by the front wall of the piston to the outlet.

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The cartridges mentioned are suitable for storing and dispensing sealing compounds, adhesives and other hardenable materials. The piston is driven forward by inserting a drive disk of the squeezing tool into the piston, which drives the piston when the squeezing tool is operated. Another possibility is to drive the piston pneumatically by applying compressed air to the rear end of the cartridge, which drives the piston forward. The piston, which consists of a one-piece plastic body, must not be too hard so that it can nestle against the inside of the cartridge wall, with the wiper lips being pressed firmly against the cartridge wall.

If the cartridge contains a viscous and particularly sticky mass, there is a risk that the piston will stick locally to the cartridge wall. If the piston is then pushed forward to squeeze out the mass, it will stick to the cartridge wall at one point on its circumference and there is a risk of the piston tipping over. This deforms the piston so that it assumes an inclined position inside the cartridge chamber. On the one hand, this creates the risk that the cartridge contents will come into contact with air and crosslink, and on the other hand, the deformation of the piston makes it impossible to continue using the cartridge to squeeze out the mass. A cartridge with a tilted piston can practically no longer be used. The risk of the piston tipping over _is particularly high with pistons that are pushed forward with compressed air.

The invention is based on the task of creating a cartridge piston of the type specified in the preamble of claim δ which is protected against deformations in the cartridge chamber while retaining its sealing properties.

This object is achieved according to the invention with the features specified in the characterizing part of claim 1

Features*
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The cartridge piston according to the invention has a conventional piston body, as used for squeezing out viscous masses, such as sealing compounds. In cases where the cartridge contains a material that tends to stick the piston body to the cartridge wall, a reinforcing ring made of relatively rigid material is inserted into the cartridge body, which supports the casing of the cartridge body from the inside, so that the piston containing the reinforcing ring is stiffened and secured against compression. Although the piston is thus rigid overall, the ability of the casing to cling to the cartridge wall is retained. In particular, the elasticity of the

~* Wiper lips not reduced by the internal support of the piston body.

The cartridge piston according to the invention can be used in all types of cartridges, but it is preferably used in aluminum cartridges that contain viscoplastic or slightly adhesive masses.

A particular advantage is that the same piston body without reinforcement ring for cartridges

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Can be used for cartridges containing a mass where the risk of the piston sticking to the ^cartridge is low, while the piston body with reinforcement ring is used for cartridges where the risk of the piston sticking is particularly high due to their contents. For a wide variety of masses, only one type of piston body is therefore required, which can optionally be equipped with a reinforcement ring. The assembly of the reinforcement ring is very simple, because the reinforcement ring is simply pushed into the cavity of the piston body, where it is held in place by clamping or rubbing .

The reinforcement ring does not require any changes to

, the pressing tools, because it determines the external dimensions

of the piston is not changed. If the pressing tool

|i is equipped with a driving disc, this can

at the rear end of the reinforcement ring,

f 20 whereby the reinforcement ring transmits the propulsion force to the

piston body.

The reinforcement ring is conveniently attached to its

"' rear end provided with an inner flange.

This inner flange makes it easier to grip the driving disk of the extrusion tool and it increases the _dimensional stability of the reinforcement insert.

To prevent the reinforcement ring from shifting in the piston body before inserting the cartridge piston into the cartridge, the reinforcement ring can be

have an outwardly protruding winding hook profile at its front end. The supply of cartridge pistons to a filling machine is usually carried out via vibrating

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f Os. derer or other vibrating devices that subject the piston to acceleration forces. The barb profile prevents the reinforcement rings previously inserted into the piston bodies from migrating out of the piston bodies again.

There are cartridge pistons that have a conical ring collar inside their cavity, which protrudes inwards from the corner between the casing and the front wall and causes the front end of the piston to expand when the drive disk of the squeezing tool presses against it. In the cartridge piston according to the invention, the reinforcing ring, which the drive disk can engage, presses against this ring collar. In this way, the expansion function of the ring collar is retained.

In the following, an embodiment of the invention is explained in more detail with reference to the drawings.
20

Show it:

Fig. 1 a longitudinal section through a cartridge with

Cartridge piston and
25

Fig. 2 is an exploded view of the cartridge piston, which consists of the piston body and the reinforcing ring.

According to Fig. 1, a cylindrical cartridge 10 is provided, which can be made of metal or plastic, for example. The one-piece cartridge 10 has a cylindrical casing 11, which is closed at one end by an end wall 12, in which a

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nozzle 13 is provided. The piston 14 is movable in the cartridge 10.

The piston 14 has a cylindrical casing 15, the outer diameter of which is slightly smaller than the inner diameter of the casing 11 of the cartridge. At the front end of the casing 15 there is a radially protruding bead 16, behind which a first sealing lip 17 is arranged, which also protrudes outwards.

Additional sealing lips 18 and 19 are located near the rear end of the casing 15.

The front end of the casing 15 is closed by the front wall 20 which is curved forwards. " In the centre of the front wall 20 there is a conical projection 21, while on the inside of the front wall 20 there is an annular rib 22. The tip 21 and the rib 22 serve to stiffen

the front wall 20.
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A truncated cone-shaped ring collar 23 protrudes from the annular edge where the jacket 15 and the end wall 20 meet into the cavity 24 inside the piston body 14. When a propulsion disk is pushed forward from the rear open end of the piston body into the cavity 24, this propulsion disk strikes the tapered end of the ring collar 23. The front end of the jacket 15 is slightly widened by the ring collar 23, so that the bead 16

&bull;&Oacgr; is pressed firmly against the cartridge casing 11 when the piston body 14 is driven against the force of the plastic mass in the cartridge 10.

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The piston body 14 described consists of a one-piece plastic part made of medium-hard plastic. Although the piston body is relatively rigid in the area of its front wall 20, it is easily deformable in the area of the rear end.

In order to increase the rigidity of the piston, the reinforcement ring 25 is provided, which can be inserted into the cavity 24. This reinforcement ring 25 is made of relatively hard plastic. It has a cylindrical shape and its outer diameter is slightly larger than the inner diameter of the casing 15, so that the reinforcement ring can be inserted into the piston body 14 in a clamping or frictional manner. At the front end of the reinforcement ring 25, an external U-shaped barb profile 26 is provided, which allows the reinforcement ring 25 to be pushed into the piston body 14, but makes it difficult to pull it out. At the rear end of the reinforcement ring 25 there is an inward-facing flange 27, which gives the reinforcement ring even greater dimensional stability and also serves to make it easier to attach a propulsion disk.

The length of the reinforcing ring 25 is such that the reinforcing ring, when its front end abuts against the annular collar 23, does not protrude from the rear end of the piston body 14. As can be seen from Fig. 1, the reinforcing ring 25 presses against the annular collar 23 so that its effect of spreading the piston body 14 apart when a mechanical propulsive force is exerted on the piston body is maintained even when the reinforcing ring 25 is inserted.

The piston body 14 can be used either with or without a reinforcing ring 25, depending on the type of application or the plastic mass that is to be propelled by the piston.

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Claims (1)

EXPECTATIONS 1. Cartridge piston for squeezing a viscous mass out of a cylindrical cartridge, comprising a one-piece piston body (14) made of medium-hard plastic, with a jacket (15) running parallel to the cartridge wall (10) and having molded-on scraper lips (17, 18, 19), and an end wall (16) closing one end of the jacket (15) _which , together with the jacket (15), delimits a cavity (24) open at the rear end, characterized in that a reinforcing ring (25) is provided which can be inserted into the casing (15) in a clamping manner, the rigidity of which is greater than that of the piston body (14) and which stiffens the casing (15) of the piston body against deformation. 2* Cartridge piston according to claim 1, characterized in that the reinforcing ring (25) has an inner flange (27) at its rear end. 3. Cartridge piston according to claim 1 or 2, characterized in that the reinforcing ring (25) has an outwardly projecting barb profile (26) at its front end. -&Igr;&Ogr;&Iacgr;. Cartridge piston according to one of claims 1 to 4, characterized in that the reinforcing ring (25) is designed to counteract a force which is inclined inwards into the cavity (24) projecting conical ring collar (23) of the piston body (14). 5. Cartridge piston according to one of claims 1 to 4, characterized in that the reinforcing ring (25) has such a length that its rear end does not protrude beyond that of the jacket (15) of the piston body (14).