DE20115432U1 - Cartridge with piston lock - Google Patents

Description

Cartridge with piston lock

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

Joint sealants, adhesives, pastes and the like are often stored in plastic cartridges that have one or more material receiving chambers with an outlet opening and associated feed pistons for discharging the cartridge contents. Such cartridges are usually hermetically sealed on both sides before they are actually used. The cartridges are sealed at the lower end by the axially movable feed pistons and at the upper end by a plug or screw cap that can be removed for use. However, many of the materials contained in cartridges tend to outgas at higher temperatures. This creates internal pressure in the material receiving chambers, which can lead to the feed piston being pushed out of the material receiving chambers during storage or transport of the cartridges.

In order to prevent the delivery piston from being pushed out in an unwanted way, plastic rings are usually used to prevent the piston from escaping. These are either placed on the end of the cartridges using a snap lock or attached to the cartridges using friction welding. However, these solutions are complex and expensive to manufacture. Attachment using friction welding is particularly time-consuming and relatively expensive. In addition, the known snap-on connections cannot be used for all cartridges. In particular, in the case of coaxial cartridges manufactured as a one-piece injection-molded part, in which, for example, a first component that is prone to outgassing is arranged in an inner tube within an outer tube that accommodates the second component, the hook-shaped undercut required for snapping on cannot be attached to the inner tube for manufacturing reasons.

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The object of the invention is to provide a cartridge of the type mentioned at the outset, which has a cost-effective and quickly mountable piston safety device to prevent the piston from accidentally escaping from the cartridge.

This object is achieved by a cartridge having the features of claim 1. Expedient embodiments and advantageous further developments of the invention are specified in the subclaims.

A significant advantage of the cartridge according to the invention is that the piston is secured by simply clamping or cutting a securing element and no additional welding, gluing or snap closures are required. This makes the manufacture of cartridges with such securing devices considerably easier. The effort and costs for manufacturing the securing elements can also be reduced. Instead of an expensive injection molding tool for a plastic ring, the securing element in the securing device according to the invention can be manufactured using a comparatively inexpensive cutting tool.

Another advantage of the invention is the simplified assembly. The locking element can be inserted into the cartridge tube relatively easily and quickly. No complex connection processes are required.

In a particularly useful embodiment of the invention, the securing element is a ring disk made of spring steel, which rests under tension against the inner wall of a corresponding receiving chamber in the manner of a disc spring. The ring disk can be used, for example, at the rear end of a central receiving tube of a coaxial cartridge. If required, such a securing disk could also be used to secure the ring piston arranged around the central receiving tube in a corresponding manner. The piston can also be secured in this way in other single and multi-component cartridges.

The ring disk is conveniently mounted so that it is curved or angled towards the piston. When the piston then presses on the ring disk,

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the radial force on the outside of the ring disk so that it wedges further into the inner wall of the material receiving chamber.

Further features and advantages of the invention will become apparent from the following description of a preferred embodiment with reference to the drawing. It shows.

Figure 1 a rear end of a cartridge with a piston and a locking ring

in storage condition;

Figure 2 a rear end of a cartridge with a piston and a locking ring

in function and

Figure 3 shows a partially illustrated push-in plunger for mounting the in Figures 1

and 2 shown retaining ring.

Figures 1 and 2 show the rear end of a cartridge 1, which usually has a mouthpiece (not shown) at the upper end. The cartridge 1, which is made of plastic, contains a cylindrical material receiving chamber 2 in which a piston 3 designed as an ejection piston is arranged so as to be axially displaceable. A spring-loaded metal locking ring 5 is inserted at the rear end 4 of the cartridge and rests under tension against the inner wall 6 of the material receiving chamber 2.

The locking ring 5 consists in a practical design of a ring disk made of spring steel, a few tenths of a millimeter thick, which can be inserted into the material receiving chamber 2 in a particularly simple and energy-saving manner via a pressing ram 7 shown schematically in Figure 3. The pressing ram 7 contains a front receiving pin 8 and a conical contact surface 9, through which the locking ring 5 can be pushed into the material receiving chamber 2 in the manner of an inwardly curved disc spring. Due to the resulting pre-tension of the locking ring 5 and due to its low material thickness, the locking ring 5 can be pressed into the inner wall 6 of the material receiving chamber 2 with its radial outer side during storage, so that in addition to the frictional holding, a positive fixing of the locking ring 5 to the inner wall of the material receiving chamber 2 is also achieved. If there is now

an overpressure is formed, the piston 3 is pressed against the locking ring 5 which is inclined inwards, as shown schematically in Figure 2. The locking ring 5 is thereby pressed further radially outwards and thus wedged more firmly against the inner wall 6 of the material receiving chamber 2.

The invention was explained above using a simple cartridge with only one cylindrical material receiving chamber. However, it can of course also be used for two- and multi-component cartridges with several material receiving chambers and several pistons.

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Claims (8)

1. Cartridge ( 1 ) with at least one material receiving chamber ( 2 ), a piston ( 3 ) axially displaceable in the material receiving chamber ( 2 ) and a piston safety device for preventing an undesired exit of the or at least one piston ( 3 ) from the associated material receiving chamber ( 3 ), characterized in that the piston safety device is a safety element ( 5 ) held in a form-fitting and/or friction-fitting manner on the inner wall ( 6 ) of the at least one material receiving chamber ( 2 ). 2. Device according to claim 1, characterized in that the securing element ( 5 ) is a resilient locking washer. 3. Device according to claim 1 or 2, characterized in that the securing element ( 5 ) is an annular locking disk arranged in the manner of a disc spring. 4. Device according to one of claims 1 to 3, characterized in that the securing element ( 5 ) consists of metal. 5. Device according to one of claims 1 to 4, characterized in that the securing element ( 5 ) consists of spring steel. 6. Device according to one of claims 1 to 5, characterized in that the securing element ( 5 ) has a thickness of a few tenths of a millimeter. 7. Device according to one of claims 1 to 6, characterized in that the securing element ( 5 ) is curved or inclined in the direction of the piston ( 3 ). 8. Device according to one of claims 1 to 7, characterized in that the securing element ( 5 ) can be inserted into the material receiving chamber ( 3 ) by means of a pressing plunger ( 7 ).