Stainless steel machine tool for workpiece polishing and cutting

Abstract

The invention relates to the technical field of laser cutting machine tools, and discloses a stainless steel machine tool for workpiece polishing and cutting, which comprises a mounting sliding block driven by a three-dimensional moving platform, a laser is mounted on the mounting sliding block, and the laser is provided with a coaxial nozzle; a protective film is arranged on the workpiece surface; the controllable windowing unit is used for forming a long and narrow window strip on the protective film along the neighborhood of a preset cutting track and reserving the edges of the protective film on the two sides; and the suction cover is arranged around the laser, and the bottom of the suction cover is provided with a skirt edge and is communicated with an external pumping unit. Through the integrated design of a long and narrow window and a quasi-closed channel, the edges of protective films on the two sides serve as natural side walls to form the quasi-closed channel with an annular skirt edge and the surface of a workpiece, and the front electromagnetic valve and the rear electromagnetic valve are matched for gating suction, so that cutting smoke dust and particles are bound above a window belt and directionally sucked into a suction cover in an entrainment mode; and the surface state that the surface is clean after being cut is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser cutting machine tools, in particular to a stainless steel machine tool for workpiece polishing cutting. BACKGROUND

[0002] Laser cutting has been widely used for the machining of the shape and opening of stainless steel plates due to its small heat-affected zone, narrow cutting seam and high efficiency. Typical equipment includes a three-axis or gantry type moving platform, a beam shaping / scanning assembly and a coaxial nozzle for spraying process gas (nitrogen, air or inert gas), and the workpiece is placed on a clamping tool or a grid bed. During the machining process, the molten or vaporized metal and flux may splash, vaporize and form particles with a size ranging from sub-microns to tens of microns, which may easily form re-deposits and discoloration bands on the plate surface, increasing the cost of subsequent polishing and cleaning.

[0003] In order to reduce pollution, the prior art mainly adopts the following measures: (1) Increasing the gas pressure of the nozzle or using a side-blowing "air knife" to try to push the slag out of the cutting seam; (2) Arranging a fixed exhaust hood / negative pressure chamber above the working area or below the worktable to exhaust and remove the smoke and dust; However, the above-mentioned solutions still have the following common problems: Firstly, the open flow field of the surface source: the nozzle is in an open space, and after the jet flow forms a boundary layer on the plate surface, the smoke and dust and particles easily spread circumferentially along the plate surface. The fixed exhaust hood has low capture efficiency due to its long distance from the cutting seam and fixed relative position; Therefore, for parts that require mirror surface or fine polishing, the above problems will directly increase the workload of subsequent polishing and cause unstable quality risks. SUMMARY

[0004] The present application aims to provide a stainless steel machine tool for workpiece polishing cutting to solve at least one of the technical problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a stainless steel machine tool for workpiece polishing cutting, comprising a mounting sliding block driven by a three-dimensional moving platform, a laser device mounted on the mounting sliding block, and a coaxial nozzle of the laser device; The workpiece surface is provided with a protective film; A controllable windowing unit is used to form a long and narrow window belt on the protective film along the neighborhood of a predetermined cutting track and to retain the edges of the protective film on both sides; And, an exhaust hood is arranged around the laser device, the bottom of the exhaust hood is provided with a skirt and is in communication with an external exhaust unit; Wherein, in the cutting process, the skirt, the workpiece surface and the edge of the protective film jointly define a quasi-closed channel extending along the long window belt to direct the smoke and particles generated by the cutting seam into the skirt to suppress their circumferential diffusion and redeposition on the installation slider plate surface.

[0006] Optionally, the outer wall of the installation slider is fixed with a follow-up ring frame sleeved on the outer ring of the laser, the suction cover is designed in a ring shape at the bottom of the follow-up ring frame, the follow-up ring frame is further designed with a gas collecting ring above, a plurality of connecting pipes individually connected with the suction cover are connected between the gas collecting ring and the follow-up ring frame, each connecting pipe is independently controlled by an electromagnetic valve, and the gas collecting ring is connected with an external exhaust unit through a negative pressure guide pipe.

[0007] Optionally, the controllable window opening unit comprises a rotating hollow pipe rotatably installed in the inner ring of the follow-up ring frame, the inner wall of the rotating hollow pipe is provided with a ring-shaped cavity with a hollow bottom, and a piston ring vertically adjustable is installed on the inner wall of the rotating hollow pipe.

[0008] Optionally, the inner ring wall of the rotating hollow pipe is rotatably installed with a swing plate, the outer wall of the swing plate is provided with a sliding groove, the sliding groove comprises two vertical grooves and an arc-shaped groove connected in the middle, a limit pin is fixed on the outer wall of the swing plate at the center of the arc-shaped groove, a turnover plate is rotatably installed on the inner wall of the vertical plate through a pin, the pin is slidably installed in the sliding groove, a long groove is further formed on the outer wall of the turnover plate, the limit pin is slidably inserted in the long groove, and the cutter is fixed on the end of the turnover plate.

[0009] Optionally, a constant pressure wheel is rotatably installed on the end of the turnover plate close to the cutter, and the tip of the cutter exceeds the constant pressure wheel by a length equal to the thickness of the protective film.

[0010] Optionally, a controller for controlling the rotation adjustment of the rotating hollow pipe is further provided, and the controller can adjust the rotation angle of the rotating hollow pipe according to the cutting track, so that the two cutters can always be parallel to the cutting track.

[0011] Optionally, the controllable window opening unit is scanned by the laser along the equidistant offset lines of the cutting track by two circles at low power, or the window belt area is implemented by face filling scanning.

[0012] Optionally, a distance sensor is arranged on the bottom of the installation slider and cooperates with the follow-up Z-axis to maintain a constant gap between the skirt and the workpiece surface.

[0013] Optionally, a sacrificial strip slot and an exhaust pipeline in communication with the exhaust unit are further arranged below the cutting track for backside slagging in the penetration stage.

[0014] Compared with the prior art, the present application has the following advantages: Firstly, the present application uses the edge of the protective film on both sides as the natural side wall to form a quasi-closed channel with a height of 1-3 mm together with the annular skirt and the surface of the workpiece, and cooperates with the selection of the suction of the electromagnetic valve in front and back to make the cutting smoke and particles be restrained above the window belt and be directed to be sucked into the suction cover, thereby reducing the amount of re-deposition on the board surface, shortening the width of the color change zone, and realizing the surface state of "cleaning after cutting".

[0015] Secondly, the present application uses the double-mode controllable windowing unit (mechanical flip cutter or low-power laser scanning) to remove the protective film only in the neighborhood of the cutting seam before cutting, retains the film edge with a height of 0.05-0.15 m as a flow field baffle, and uses the flip recovery of the cutter and the constant pressure wheel limiting structure to ensure that the film break is neat and does not damage the base material, and the laser scanning mode is non-contact and residue-free, so that the removal amount of subsequent polishing is further reduced, and the secondary processing cost is significantly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of the three-dimensional structure of the present application; Figure 2 is an enlarged view of A in the present application Figure 1 ; Figure 3 is an enlarged perspective view of the follow-up circular ring frame and the structure thereon of the present application; Figure 4 is a sectional perspective view of the follow-up circular ring frame of the present application; Figure 5 is an exploded perspective view of the cutter switching structure of the present application Figure 1 ; Figure 6 is an exploded perspective view of the cutter switching structure of the present application Figure 2 ; Figure 7 is a schematic diagram of the state of the cutter of the present application in the retracted state; Figure 8 is a schematic diagram of the state of the flip plate in the flipping process of the present application; Figure 9 is a schematic diagram of the state of the cutter of the present application in the cutting state; Figure 10 is a schematic diagram of the quasi-closed channel of the present application.

[0017] In the figure: 1, three-dimensional moving platform; 2, mounting slider; 3, laser; 4, follow-up ring frame; 5, suction cover; 6, skirt; 7, gas collection ring; 8, connecting pipe; 9, electromagnetic valve; 10, negative pressure guide pipe; 11, rotating empty pipe; 12, piston ring; 13, vertical plate; 14, turnover plate; 15, swing plate; 16, limit pin; 17, sliding groove; 18, bolt; 19, constant pressure wheel; 20, cutter; 21, long groove; 22, workpiece; 23, quasi-closed channel. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0019] Please refer to Figures 1 to 10 The present application provides a technical solution: a stainless steel machine tool for workpiece polishing and cutting, comprising a mounting slider 2 driven by a three-dimensional moving platform 1, a laser 3 mounted on the mounting slider 2, and the laser 3 having a coaxial nozzle. The surface of the workpiece 22 is provided with a protective film; A controllable windowing unit is used to form a narrow window strip along the neighborhood of the predetermined cutting track on the protective film and retain the edges of the protective film on both sides; And a suction cover 5 is arranged around the laser 3, the bottom of which is provided with a skirt 6 and is in communication with an external exhaust unit; During the cutting process, the skirt 6, the surface of the workpiece 22 and the edges of the protective film jointly define a quasi-closed channel 23 extending along the narrow window strip, so as to direct the smoke and particles generated by the cutting seam into the skirt 6, thereby inhibiting the circumferential diffusion and redeposition of the smoke and particles on the surface of the mounting slider 2.

[0020] When the stainless steel machine tool is in use, the workpiece 22 is first subjected to laser cutting, and then the cutting position is subjected to polishing treatment. In order to reduce the influence of the laser cutting process on the subsequent polishing process, the smoke and particles generated by the laser need to be treated during the cutting process, and the specific mode is as follows: First, a controllable windowing unit is used to form a narrow window strip along the neighborhood of the predetermined cutting track on the protective film of the workpiece 22 and retain the edges of the protective film on both sides, and then the protective film in the narrow window strip region is peeled off, so as to avoid the problem of easy rolling, burning and sticking of the film during the subsequent laser cutting process; Then the three-dimensional mobile platform 1 drives the installation slider 2 and the laser 3 to move along the predetermined cutting track for cutting. In the cutting process, the coaxial nozzle on the laser 3 sprays inert gas or other protective gas to blow the smoke and particles generated by laser cutting downward. The skirt 6, the surface of the workpiece 22 and the edge of the protective film jointly define a quasi-closed channel 23 extending along the narrow window belt, so as to direct the smoke and particles generated by cutting into the skirt 6 to inhibit the circumferential diffusion and redeposition of the smoke and particles on the surface of the installation slider 2. It is worth mentioning that the edge of the protective film on both sides is about 0.05-0.15mm high, but in the 1-3mm high interlayer formed by the skirt 6 and the surface of the workpiece 22, it is sufficient to block the lateral entrainment and limit the airflow in the narrow channel above the window belt. The skirt 6 at the bottom of the suction hood 5 and the workpiece 22 maintain a small gap of 1-3mm, which cooperates with the film edge and the plate surface to enclose a quasi-closed channel 23 with “hood on top, plate on the bottom and film edge on both sides”. The nozzle airflow pushes the splashes into the narrow window belt and then directs them into the hood under negative pressure, so as to achieve the effect of directional guidance, thereby reducing the formation of redeposits and discoloration on the plate surface, and further reducing the subsequent polishing and cleaning cost.

[0021] It is worth noting that through “cutting to generate a polishing compatible surface”, the same layer of protective film simultaneously assumes three roles: Mechanical barrier - to prevent splashes from directly hitting the substrate; Flow field wall - to form a “quasi-closed channel 23” with the suction hood 5 to guide the smoke to the exhaust port; Process reference - the film window edge becomes the zero reference for the subsequent polishing offset track, eliminating the need for secondary edge finding.

[0022] In one of the more preferred embodiments, an implementation and control method of the suction hood 5 are provided. The outer wall of the installation slider 2 is fixed with a follow-up ring frame 4 sleeved on the outer circle of the laser 3. The suction hood 5 is designed in a ring shape at the bottom of the follow-up ring frame 4. The follow-up ring frame 4 is further designed with a gas collecting ring 7 above it. A plurality of connection pipes 8 are connected between the gas collecting ring 7 and the follow-up ring frame 4, and each connection pipe 8 is independently controlled by an electromagnetic valve 9. The gas collecting ring 7 is connected with an external exhaust unit through a negative pressure conduit 10.

[0023] For details, please refer to Figure 3 During suction, the external exhaust unit sucks through the negative pressure conduit 10, and the gas collecting ring 7 and the connection pipe 8 apply negative pressure to the plurality of suction hoods 5 to directionally extract the smoke and particles; And in order to further improve the directional flow effect, that is, the smoke and dust is drawn into the suction cover 5 from the quasi-closed channel 23, each connecting pipe 8 is independently controlled by the electromagnetic valve 9, and on the cutting track, the connecting pipes 8 before and after the laser 3 are opened by the electromagnetic valve 9, only the upstream and downstream two sections of the tool path tangential direction are activated, so that the "only front and rear two sections gating" is aligned with the long window belt to form two quasi-closed channels 23, and the smoke and dust are quickly sucked into the cover along the quasi-closed channel 23, compared with "full ring always open" or "single port fixed suction", the near-source capture efficiency can be further improved; At the same time, the interlayer flow defined by the gating section and the film edge can bind the gas-solid two-phase in the window belt area, so as to reduce the mass of surface redeposition, and also can effectively reduce the color change width, and reserve a cleaner boundary for subsequent polishing.

[0024] In the above embodiment, a controllable window opening unit is provided. The controllable window opening unit comprises a rotating hollow pipe 11 rotatably installed in the inner ring of the follow-up ring frame 4, and the inside of the rotating hollow pipe 11 is provided with a bottom-hollow annular cavity, the inner wall of the rotating hollow pipe 11 is provided with a piston ring 12 capable of vertical lifting adjustment, the bottom of the piston ring 12 is fixed with two vertical plates 13, and the two vertical plates 13 are each provided with a cutter 20.

[0025] For details, please refer to Figure 4 Before laser cutting, the piston ring 12 is adjusted by external structure control, and the vertical plate 13 and the cutter 20 are moved up and down by upward and downward movement of the piston ring 12, so that the cutter 20 contacts with the protective film, and the two side-by-side designed cutters 20 cut the long window belt on the protective film; After cutting, the piston ring 12 drives the vertical plate 13 and the cutter 20 to retract into the rotating hollow pipe 11, so as to avoid the adhesion of smoke and particles on the cutter 20.

[0026] Among them, the lifting adjustment of the piston ring 12 can adopt a pneumatic way, for example, a sealed space is formed between the piston ring 12 and the rotating hollow pipe 11, and the sealed space is injected or pumped by external pneumatic structure (such as air pump), so that high pressure or negative pressure is formed in the sealed space, and then the piston ring 12 is driven to reciprocate in the rotating hollow pipe 11 for adjustment.

[0027] In a further more preferred embodiment, a telescopic cutter 20 is provided. The inner ring wall of the rotating air pipe 11 is rotatably provided with a swing plate 15, the outer wall of the swing plate 15 is provided with a sliding groove 17, the sliding groove 17 includes two vertical grooves and an arc-shaped groove connected in the middle, and the outer wall of the swing plate 15 at the center of the arc-shaped groove is fixedly provided with a limiting pin 16, the inner wall of the vertical plate 13 is rotatably provided with a turnover plate 14 through a bolt 18, the bolt 18 is slidably arranged in the sliding groove 17, and the outer wall of the turnover plate 14 is further provided with a long groove 21, the limiting pin 16 is inserted and slidably arranged in the long groove 21, and the cutter 20 is fixed at the end position of the turnover plate 14.

[0028] Specifically refer to Figure 5 and Figure 6 When the piston ring 12 drives the vertical plate 13 to move downward, the turnover plate 14 is driven to move downward, and the bolt 18 is slid downward in the sliding groove 17, and the limiting pin 16 is also slid in the long groove 21, when the bolt 18 slides to the arc-shaped groove position of the sliding groove 17, the turnover plate 14 rotates around the limiting pin 16 as the center, as shown in Figure 8 ; When the bolt 18 slides to the lower half of the vertical groove of the sliding groove 17 again, the turnover plate 14 is turned over by 180 degrees, so that the cutter 20 at the end thereof is turned over to the downward state, that is Figure 9 , to complete the subsequent cutting process; After cutting, the piston ring 12 and the vertical plate 13 move upward to reset, the turnover plate 14 is reset to turn over by 180 degrees through the sliding cooperation of the bolt 18 and the sliding groove 17 and the sliding cooperation of the limiting pin 16 and the long groove 21, until it is reset to Figure 7 ; In this way, the state of the cutter 20 is switched by turning over, so that the cutter 20 can be as far away from the cutting area below as possible after the cutting is completed, further avoiding that the residues and smoke particles are attached to the cutter, avoiding that the protective film is scratched during subsequent cutting, and ensuring the cutting efficiency.

[0029] In one of the more preferred embodiments, a constant pressure wheel 19 is rotatably arranged at the end of the turnover plate 14 close to the cutter 20, and the tip of the cutter 20 exceeds the constant pressure wheel 19 by a length equal to the thickness of the protective film.

[0030] Specifically refer to Figure 6 , by arranging the constant pressure wheel 19 at the end of the turnover plate 14, when the cutter 20 contacts and cuts the protective film, the constant pressure wheel 19 can limit the cutting depth of the cutter 20, so that the cutter 20 can cut the protective film, while avoiding scratches on the workpiece 22, and also reducing the difficulty of the subsequent polishing process.

[0031] In one of the more preferred embodiments, a controller is further included for controlling the rotation adjustment of the rotating air pipe 11, and the controller is capable of adjusting the rotation angle of the rotating air pipe 11 according to the cutting trajectory, so that the two cutting knives 20 can always be parallel to the cutting trajectory.

[0032] Since the three-dimensional moving platform 1 drives the installation sliding block 2 and the laser 3 to move by X / Y axis movement, and since the two cutting knives 20 are designed side by side, in order to avoid the moving trajectory of the two cutting knives 20 intersecting when the installation sliding block 2 directly turns a corner or bends, thereby affecting the cutting of the narrow window strip; Therefore, when the installation sliding block 2 changes the trajectory, the controller adjusts the rotation angle of the rotating air pipe 11 according to the change of the cutting trajectory, so that the two cutting knives 20 can always be parallel to the cutting trajectory in the next section of the trajectory, thereby ensuring the formation of the narrow window strip. The rotation adjustment of the rotating air pipe 11 can be controlled by a servo motor, and the angle and direction of the rotation adjustment can be controlled by the controller.

[0033] In the second embodiment, unlike the first embodiment, a second embodiment of the controllable window opening unit is provided. The controllable window opening unit is provided with a laser 3 that performs double-circle scanning along the equidistant offset lines of the cutting trajectory with low-power laser, or performs surface filling scanning on the window strip area.

[0034] As can be seen from the above, the formation of the narrow window strip is realized by the mechanical cutting of the cutting knife 20, and can also be realized by the double-circle scanning of the laser 3 along the equidistant offset lines of the cutting trajectory with low-power laser, or the surface filling scanning on the window strip area, only cutting the film without melting the plate material, and the laser cutting method is accurate in positioning, and the median or lower limit of the upper interval can be taken, which can also reduce the design of the mechanical structure.

[0035] In one of the more preferred embodiments, the installation sliding block 2 is provided with a distance sensor at the bottom and cooperates with the follow-up Z axis to maintain a constant gap between the skirt 6 and the surface of the workpiece 22.

[0036] In one of the more preferred embodiments, a sacrificial strip slot and an exhaust pipeline that communicates with the exhaust unit are further included below the cutting knife path, for backside slag removal during the penetration stage.

[0037] By adding a sacrificial strip slot and an exhaust pipeline below the workpiece 22, backside slag removal is performed during the penetration stage, and the above-mentioned directional guidance of smoke and dust is further combined, which maximizes the reduction of residual slag and improves the cutting accuracy, thereby preparing for the subsequent polishing process.

[0038] The standard parts used in the embodiment can be directly purchased from the market, and the non-standard structural parts according to the description and drawings can also be directly processed according to the existing technical knowledge without any doubt, and the connection mode of each part adopts the mature conventional means in the existing technology, and the machinery, parts and equipment adopt the conventional models in the existing technology, so specific description is not made here.

[0039] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A stainless steel machine tool for polishing and cutting workpieces, comprising a mounting slide (2) driven by a three-dimensional moving platform (1), wherein a laser (3) is mounted on the mounting slide (2), and the laser (3) has a coaxial nozzle, characterized in that: The surface of the workpiece (22) is provided with a protective film; A controllable window opening unit is used to form a narrow window strip in the vicinity of the protective film along a predetermined cutting trajectory while retaining the edges of the protective film on both sides. And, a suction shroud (5) arranged around the laser (3) has a skirt (6) at its bottom and is connected to an external suction unit; During the cutting process, the skirt (6), the surface of the workpiece (22) and the edge of the protective film together define a quasi-closed channel (23) extending along the narrow window strip, so as to directionally draw the smoke and particles generated by the cutting into the skirt (6) to suppress their circumferential diffusion and redeposition on the mounting slider (2) plate.

2. The stainless steel machine tool for polishing and cutting workpieces according to claim 1, characterized in that: The outer wall of the mounting slider (2) is fixed with a follower ring frame (4) sleeved on the outer ring of the laser (3). The suction hood (5) is designed in a ring shape at the bottom of the follower ring frame (4). A gas collecting ring (7) is also designed above the follower ring frame (4). Multiple connecting pipes (8) that are individually connected to the suction hood (5) are connected between the gas collecting ring (7) and the follower ring frame (4). Each connecting pipe (8) is independently controlled by a solenoid valve (9). The gas collecting ring (7) is connected to the external suction unit through a negative pressure conduit (10).

3. The stainless steel machine tool for polishing and cutting workpieces according to claim 1, characterized in that: The controllable window opening unit includes a rotating hollow tube (11) rotatably installed in the inner ring of the follower ring frame (4), and the interior of the rotating hollow tube (11) is a ring-shaped cavity with a hollow bottom. The inner wall of the rotating hollow tube (11) is equipped with a piston ring (12) that can be vertically adjusted. The bottom of the piston ring (12) is fixed with two vertical plates (13), and each of the two vertical plates (13) is equipped with a cutter (20).

4. The stainless steel machine tool for polishing and cutting workpieces according to claim 3, characterized in that: The inner ring wall of the rotating tube (11) is rotatably mounted with a swing plate (15). The outer wall of the swing plate (15) is provided with a sliding groove (17). The sliding groove (17) includes two vertical grooves and an arc groove that is connected in the middle. The outer wall of the swing plate (15) located at the center of the arc groove is fixed with a limit pin (16). The inner wall of the vertical plate (13) is rotatably mounted with a flip plate (14) through a pin (18). The pin (18) passes through and slides in the sliding groove (17). The outer wall of the flip plate (14) is also provided with a long groove (21). The limit pin (16) is inserted into and slides in the long groove (21). The cutter (20) is fixed at the end of the flip plate (14).

5. The stainless steel machine tool for polishing and cutting workpieces according to claim 4, characterized in that: The end of the flip plate (14) near the cutter (20) is also rotatably mounted with a constant pressure wheel (19), and the tip of the cutter (20) extends beyond the constant pressure wheel (19) by the same length as the thickness of the protective film.

6. The stainless steel machine tool for polishing and cutting workpieces according to claim 3, characterized in that: It also includes a controller for controlling the rotation adjustment of the rotating tube (11), and the controller can adjust the rotation angle of the rotating tube (11) according to the cutting trajectory so that the two cutters (20) can always be parallel to the cutting trajectory.

7. The stainless steel machine tool for polishing and cutting workpieces according to claim 1, characterized in that: The controllable window opening unit is scanned in two circles by a laser (3) with low power laser along the equidistant offset line of the cutting trajectory, or the window area is filled by surface scanning.

8. The stainless steel machine tool for polishing and cutting workpieces according to any one of claims 1-7, characterized in that: The mounting slider (2) is equipped with a distance sensor at its bottom and works in conjunction with the follow-up Z-axis to maintain a constant gap between the skirt (6) and the surface of the workpiece (22).

9. The stainless steel machine tool for polishing and cutting workpieces according to any one of claims 1-7, characterized in that: It also includes a sacrificial strip slot and an air extraction pipe located below the cutting path and connected to the extraction unit, for back-side slag removal during the penetration stage.

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