DE2015921A1 - Decompression prevention during extrusion of plastic pipe - Google Patents

Abstract

A bung has a piston and rod and a secondary piston which can move back and forth on the rod, but is held away from the main piston by a spring. This unit is inserted into the pipe which is being extruded, thus preventing decompression. Two pairs of jaws, one of which can move longitudinally, can be actuated to hold the bung in position within the pipe whilst the end is cut off, and a push rod operating into the end of the pipe repositions the bung.

Description

Device for the waste-free production of pipe sections from one continuously manufactured pipe pressurized by internal pressure The present The invention relates to a device for the waste-free production of pipe sections from a continuously manufactured tube that is subjected to an internal pressure is, plastic pipes can be produced in the extrusion process and stretched biaxiai will. In this manufacturing process, the inside of the manufactured pipe a support pressure is generated to ensure that the pipe shape after extrusion preserved. With continuous production, this internal pressure must be during the can be maintained throughout the production process. This creates difficulties for the further processing or dismemberment of the pipe, since one does not. without further keep the supporting air inside the tube. can, so far it would be -therefore It is common practice to depressurise the pipe by clamping it off during further processing. However, the resulting terminal points must be cut off from the pipe sections will, creating useless waste and requiring an additional operation will. In addition, this leaves the pinch-off, which depressurizes the pipe in places is not a purely continuous way of working.

The patent application P 17 78 323.2 includes a device for Maintaining the pressure of this supporting air, which enables continuous further processing of the pipe can be made. According to this device, a magnetizable Plug inserted into the plastic pipe that seals the pipe and of a Magnetic field is held, so that the end of the tube protruding beyond the plug is pressureless and can be cut off. However, this device has the Disadvantage that if the magnetic plug is not exactly centered in the pipe, this is pulled against the side wall of the pipe and creates considerable frictional forces here that have a detrimental effect on the functioning of the facility.

The object of the invention is to overcome these uncertainties in production thereby avoiding the need for further processing or fragmentation of continuously Manufactured pipes a separating device is used, in which mechanically through cross-clamping a sealing plug is held in the pipe.

The subject of the invention is etme for maintaining the internal pipe pressure Sealing plug combination located in the pipe, - the two mutually movable and interconnected sealing plug consists, in the pipe by a clamping Device consisting of a fixed and a movable clamping jaw, both of which let open, is held step by step and that each time from the Cutting sleeve the protruding pipe end is cut off.

For a better understanding, the invention is based on a Explained in the accompanying drawings shown example.

In Fig. 1 the manufacturing plant is sketched. That continuously Pipe A emerging from the pipe stretching plant is passed through a compensating loop 3 fed to the cutting device SV. The pipe stretching and cutting device are synchronized, the cutting device works with cycle feed T (gripper feed).

A plug combination is used to keep the supporting air inside the pipe inserted into the tube, this plug combination is alternately made by two clamping jaws held over the thin pipe wall '. The cutting is done with a saw, a Knife or a similar tool carried out in a known manner. The interaction the plug combination with the clamping jaws is shown in FIGS. 2a to 2c.

In Fig. 2a the piece of plastic pipe is shown, which is'in the cutting device SV is located, with a cutting operation being carried out became. The protruding from the SchneidbAchse 8 'pipe section 10, in which there is no Internal pressure is more, is separated with the knife 9 from the remaining pipe section li, In order to prevent the tube 11 from advancing further, the clamping jaw 1 is pending this cutting process closed, the plug 3 against the supporting pressure holds and clamps the tube 11 so that the plug 3 does not protrude into the protruding Pipe section 10 protrudes and thus impairs the cutting process could. The plug 3 is provided with a slide rod 7 in the direction of the incoming pipe, which is surrounded by a helical spring 6. On this slide rod 7 is a plug 5 slidably attached '. The mobility of the plug 5 is ensured by a sleeve 12, which is attached to the end of the slide rod 7.

This plug combination 3, 5 can with a 4 in the plastic pipe must be pushed into it.

During the cut-off, the push-in punch 4 is out of the plastic tube pulled out so that the cut piece of pipe 10 can freely fall down. During the cutting process, the 'jaw 2 is open so that the plug is in its starting position at the end of the sliding bar 7.

After cutting through the protruding pipe section 10, the clamping jaw 2 - closed. Clamping jaw 1 opens and the feed stroke starts at the same time as shown in Fig. 2b. The tube 11 and the plug 5 are advanced. In the opposite direction to the feed direction, the push-in punch comes from the open side of the pipe 4 a, which connects the plug 3, which is connected to the plug 5 via the slide rod 7 is in the position required for cutting. It then closes the clamping jaw 1 and holds the plug 5 against the internal support pressure.

Then, as shown in FIG. 2c, the clamping jaw opens 2 again and, like the push-in ram 4, runs back into the starting position. With the loosening of the clamping jaw 2, the plug 5 is released and through the between Plug 3 and 5 lying spring 6 pushed back into its starting position. That protruding pipe section 10 'can now be cut off.

The cutting process is 'conveniently carried out s-a-', that the pipe section 1D, which protrudes beyond the plug 3 ', is just equal to the length of the pipe section to be cut off, since the plug 3 is thereby used as an inner layer which ensures a clean cut without kinking the pipe will.

Furthermore, it is' useful if the external diameter of the sealing plug 3 and 5 over their entire length practically equal to the inner diameter of the 'tube is because the plug thereby exert a supporting effect on the pipe, which it during the clamping by'die clamping jaws 1 and 2 prevents buckling or buckling.

In pipes that are cut according to the invention, the internal pressure fluctuate and also assume larger values without the plug combination is pushed out of the pipe, so that a safe and waste-free production can be made of pipe sections from a continuously manufactured pipe,

Claims (5)

Claims) Continuous cutting device for pipes, the tit support air are manufactured, characterized in that one located in the pipe Combination of two mutually movable and interconnected sealing plugs (3,5) with a clamping cycle feed device (T) from a stationary one (1) and a movable jaw (2) - interacts to open alternately and are to be closed. 2. Apparatus according to claim 1, characterized in that the dem Sealing plug (5) facing away from the pipe end (1Ö) attached to a sliding rod (T) is attached to the sealing plug (3) facing the pipe end (10) and with a helical spring (6) is surrounded. 3. Device according to one of claims 1 or 2, characterized in that that the outer diameter of the sealing 'plug (3.5') over the entire length practically is equal to the inner diameter of the pipe. 4. Device according to one of claims 1 to 3, characterized in that that a movable ram (k) is attached in front of the pipe end. 5. Device according to one of claims 1 to 4, characterized in that that the path that the clamping jaw (2) covers during the feed process, at least equal and preferably just equal to the length of the pipe section to be cut is.