Process for abrasive high-pressure water jet cutting with a high-pressure water jet containing ice crystals

Abstract

The method involves branching a high pressure line (2) into two parallely running line strands (4, 5) in a direction of a nozzle (3). The strands are operated in connection with cooling tracks (6, 7) alternately in an ice crystal production phase and an ice crystal supply phase such that the strand (4) initially locked from the line and to the nozzle is provided for ice crystal production in a low pressure phase when the strand (5) initially opened to the line and the nozzle is provided for supplying ice crystals (13) to the nozzle in a high pressure phase.

Description

[0001] The invention relates to a method for abrasive high-pressure waterjet cutting with an ice crystal-containing High-pressure water jet, wherein the ice crystals are generated before the high-pressure water jet exits the nozzle and are used to separate workpieces, especially fiber-reinforced composite materials. Since the abrasive particles are only present for a limited time, contamination or Contamination of the workpiece by abrasive residues is avoided.

[0002] From DD 298 618 a method for abrasive high-pressure water jet cutting is known, in which a high-pressure The water is cooled to -10°C to -20°C before exiting the nozzle and remains in a liquid state under the given pressure conditions. remains. Upon exiting the nozzle, the high pressure drops to ambient pressure, with some of the water crystallizing into ice, so that this Ice crystals can be used as abrasives for the cutting and separation of workpieces.

[0003] A similarly based method for cutting the edge strips of a paper web is described in DE 10 2004 046 030 A1 As described. Here too, the cooled water, under high pressure, emerges as a free jet from a nozzle into normal atmospheric pressure. from, whereby ice crystals form at the latest when it hits the surface of the track to be cut.

[0004] The disadvantages of these two solutions are that a sufficient abrasive flow cannot be ensured because the The time available for the water jet exiting the nozzle before hitting the workpiece to be cut is too short to... to form the necessary ice crystals, which act as abrasives, in sufficient number and size to carry out the cutting process.

[0005] In DE 197 56 506 C2, a method for abrasive high-pressure water jet cutting is disclosed, in which the water is treated as Crushed particles of dry ice are added as an abrasive.

[0006] The method known from DE 196 32 883 A1 also works on the basis that the water is treated with a A substance is added. This process creates an abrasive in the water through changes in its state. In this case, liquid water is added to form ice crystals. Nitrogen is introduced into the water, causing at least part of the water to undergo a physical change of state and turn into ice. These ice crystals, carried by the water jet, have an abrasive effect on the workpiece after exiting the nozzle.

[0007] In the latter two methods, additional cooling of the water can be dispensed with, but their disadvantages However, this is reflected in the high level of technical equipment required for the mixing and safe handling of the respective The system requires the use of an additive (dry ice or liquid nitrogen). If the proportion of ice crystals in the water is too low, then according to the... As the abrasive jet exits the nozzle, there is a risk that the number of ice crystals will decrease to such an extent before it hits the workpiece that the abrasive cutting effect is no longer sufficiently guaranteed.

[0008] The object of the invention is to propose a method for abrasive high-pressure water jet cutting in which the ice crystals continuously and in sufficient numbers to carry out the cutting process on the workpiece, thus ensuring a stable The cutting process is to be carried out on the workpiece.

[0009] According to the invention, this problem is solved in a generic method by the features of claim 1.

[0010] The advantages of the invention are that for high-pressure water jet cutting with ice crystals a continuous and for the Cutting process of the workpiece with regard to cutting performance requires a sufficient abrasive flow with minimal equipment effort. is provided. The required ice crystals can be generated by cyclically switching between the pipe runs with the cooling sections. They must be kept on hand to ensure the continuous execution of the cutting process. Furthermore, separate and... Dosage-related additives do not need to be kept on hand and the safety handling is eliminated.

[0011] An advantageous procedural development of the invention is set out in claim 2.

[0012] They show:

[0013] Fig. 1 shows a schematic representation of the arrangement for carrying out the method according to the invention, in which the upper conductor string is in the High-pressure phase (= ice crystal supply phase, cutting phase) and the lower conduction string in the low-pressure phase (= ice crystal generation phase) is operated

[0014] Fig. 2 shows a schematic representation of the arrangement for carrying out the method according to the invention. rens, after the reciprocal switching between the line strands has taken place in such a way that the lower line strand is now in the High-pressure phase (= ice crystal supply phase, cutting phase) and the upper conduction string in the low-pressure phase (= ice crystal generation phase) is operated

[0015] Fig. 1 shows a schematic representation of the arrangement for carrying out the abrasive method according to the invention. High-pressure waterjet cutting is illustrated using a high-pressure water jet containing ice crystals. This is achieved via the high-pressure pump. 1. Water pressurized to 2000 to 3000 bar is pumped through a high-pressure line 2 towards the nozzle 3. The high-pressure line branches into two parallel line sections 4, 5, each of which is operatively connected to a cooling section 6, 7. by which the pumped water 8 is cooled to at least -10°C. Each cooling section also has two high-pressure shut-off valves 9. or 10 and a pressure limiter valve 11 or 12 is assigned.

[0016] While the pressure limiter valve 11 is closed, the high pressure flow passes through the open high pressure shut-off valves 9 to the high pressure line 2 and nozzle 3 initially operates in an open line string 4 during an ice crystal feeding phase (high-pressure phase, cutting phase), in which the Ice crystals 13, previously generated in a low-pressure phase (preferably normal pressure) of this line 4, together with the water jet 14. When the fluid exits nozzle 3 for processing the workpiece, the line 5 is separated from the high-pressure line 2 and nozzle 3. The high-pressure shut-off valves 10 are closed, but the pressure limiter valve 12 associated with the pipeline 5 is opened, thereby a low pressure develops in the pipe section 5, which is isolated from the high-pressure line 2, through which, when the water 8 is present, a change of state occurring via physical means leads to the phase transition from solid to liquid and thus to the formation of ice crystals 13 (Ice crystal formation phase). As ice crystal formation in conductor string 4 nears its end, the following occurs in conductor string 5, as shown in Fig. 2. Pressure relief valve 12 closed and the high pressure valves 10 open, while in line 4 the opening of the pressure relief valve 11 and the closure of the high-pressure valves 9 take place, so that the nozzle 3 now receives the air from the line 5 without interruption. and an abrasive flow consisting of ice crystals 13 is supplied from the water jet 14, while now in the line 4 through the The reintroduction of low pressure initiates the ice crystal formation phase.

[0017] The above-described operating method is achieved by regulating the time regime between the high-pressure and low-pressure phases. in the conductor strands 4, 5 alternately, so that the ice crystals 13 required for workpiece processing are continuously and in A sufficient number can be provided.

[0018] Depending on the specific working conditions and the associated time regime regulations, it is possible that also more than two parallel pipe sections that are operatively connected to a cooling section can be operated. 1 High-pressure pump 2 High-pressure line 3 nozzle 4 Cable harness 5 Cable harness 6 Cooling section 7 Cooling section 8 Water 9 High-pressure shut-off valve 10 High-pressure shut-off valve 11 Pressure relief valve 12 Pressure relief valve 13 ice crystals 14 water jet

[0019] This list of documents cited by the applicant was generated automatically and is solely for the better information of the Readers' contributions were included. The list is not part of the German patent or utility model application. The DPMA assumes no liability whatsoever. for any errors or omissions. Cited patent literature

[0020] - DD 298618

[0002] - DE 102004046030 A1

[0003] - DE 19756506 C2

[0005] - DE 19632883 A1

[0006]

Claims

[1] Method for abrasive high-pressure water jet cutting using a high-pressure water jet containing ice crystals, wherein the ice crystals are generated before the high-pressure water jet exits the nozzle, characterized in that the high-pressure line (2) is in The direction of the nozzle (3) is designed to branch into at least two parallel conductor strands (4, 5), which are connected to a cooling section. (6, 7) are in operative connection, wherein the conductor strings (4, 5) in conjunction with the cooling sections (6, 7) alternately in a The ice crystal generation phase and an ice crystal supply phase are operated in such a way that the flow from the high-pressure line (2) and to the The nozzle (3) initially shuts off a line (4) for ice crystal generation, which is in a low-pressure phase, while the line to High pressure line (2) and nozzle (3) initially open other line string (5) for supplying the ice crystals (13) to the nozzle (3) in its high-pressure phase (ice crystal feeding phase, cutting phase) is located. [2] Method for abrasive high-pressure water jet cutting according to claim 1 characterized in that the reciprocal working method The control of the line strings (4 , 5) in the high-pressure and low-pressure phases is achieved by regulating the time regime.