Mixing nozzle for laser processing system

Abstract

A nozzle for a laser processing head is provided. The nozzle includes a primary passage disposed within a body of the nozzle. The primary passage is configured to direct a laser beam and a primary fluid from a proximal end of the body to a distal end of the body. The nozzle also includes a set of at least one auxiliary passage disposed within the body of the nozzle and radially offset from a longitudinal axis of the primary passage. A distal portion of the auxiliary passage bifurcates into two fluid passages including (i) a first fluid passage configured to direct a first portion of the auxiliary fluid axially forward toward the distal end of the body of the nozzle, and (ii) a second fluid passage configured to direct a second portion of the auxiliary fluid radially inward to mix with the primary fluid in the primary passage.

Description

[Technical Field]

[0001] The present invention relates generally to the design of one or more nozzles for laser processing systems. [Background technology]

[0002] Material processing systems, including laser processing systems, liquid jet processing systems, and plasma arc torch systems, are widely used to process (e.g., heat, cut, gouge, and mark) materials such as metal sheets. Laser processing systems typically include a high-power laser, a gas stream, optics, and a computer-controlled numerical system (CNC). During operation, laser processing systems controllably irradiate the workpiece with a laser beam to process it, while using a gas stream to blow molten material away from the workpiece. Laser processing systems are frequently used in precision cutting processes due to the ease of control provided by the laser beam, gas stream, and laser nozzle geometry.

[0003] In laser processing systems, the flow rate profile of the gas stream is determined by the operating pressure and the physical characteristics of the nozzle geometry. Traditionally, the gas stream contains air, oxygen, nitrogen, argon, or a mixture of two or more of these gases. Oxygen and compressed air are the least expensive gases to use in the gas stream, but they can oxidize the workpiece during cutting, necessitating post-cutting treatments such as chemical finishing or grinding. If the cutting material is prone to oxidation, using nitrogen or argon in the gas stream can be effective. This is because nitrogen and argon are generally inert and do not react with the workpiece as it is being cut. However, nitrogen and argon are typically operated at much higher pressures and flow rates, making them more expensive to use than oxygen, thus increasing the cost of operating a laser processing system.

[0004] One way to change the gas flow profile in a laser processing system is to increase the velocity and pressure profiles in the peripheral region of the laser cutting nozzle compared to the central region. However, this is difficult because both the peripheral and central regions are typically supplied by the same plenum. If different pressures or gases are supplied to the two regions, the gap between the nozzle and the workpiece can create a uniform static pressure area, especially if the gap is small, minimizing the impact of different supply parameters. Furthermore, if the pressures in the peripheral and central regions of the nozzle are different, gas can backflow into the low-pressure area within the nozzle, which can generate spatter that can damage the nozzle. This means that if spatter is directed through the central region of the nozzle, it can damage optical lenses and clog the nozzle, reducing cut quality and the overall lifespan of laser consumables. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, there is a need for a nozzle for a laser processing system that allows for improved control of the pressure and flow velocity profiles of the gas flow in the laser processing system to achieve the desired cut. [Means for solving the problem]

[0006] In some embodiments, the present invention provides a nozzle for laser cutting applications configured to passively mix a primary fluid (e.g., gas) with a portion of a secondary fluid (e.g., gas) within the nozzle. The resulting nozzle design improves control over the pressure and velocity profiles of the gas flow in the region between the nozzle end face and the workpiece to achieve a desired cut in the workpiece. In some embodiments, the nozzle of the present invention is configured to create multiple fluid flow passages that are independent of one another, with one or more of these passages being introduced into the surrounding environment by venting to allow gas mixing, pressure variations, or both. These multiple passages allow for greater control of cutting variables, enabling controlled cuts with improved cut quality at lower operating costs.

[0007] In one aspect, a nozzle for a laser processing head for processing a workpiece is provided. The nozzle includes a primary passageway disposed within a body of the nozzle. The primary passageway is configured to direct a laser beam and a primary fluid from a proximal end of the body to a distal end of the body for processing the workpiece. The nozzle also includes at least one set of auxiliary passageways disposed within the body of the nozzle and radially offset from a longitudinal axis of the primary passageway. A distal portion of the at least one auxiliary passageway bifurcates into two fluid passageways, including a first fluid passageway configured to direct a first portion of the auxiliary fluid axially forward toward the distal end of the body of the nozzle to substantially cover the laser beam exiting the primary passageway, and a second fluid passageway configured to direct a second portion of the auxiliary fluid radially inward to mix with the primary fluid within the primary passageway.

[0008] In another aspect, a method for mixing at least two fluids in a nozzle for a laser processing head of a laser processing system is provided. The method includes directing a primary fluid axially forward through a primary passage disposed within a body of the nozzle from a proximal end to a distal end of the body and supplying a secondary fluid into at least one auxiliary passage disposed within the body of the nozzle. A distal portion of the auxiliary passage is configured to bifurcate into a first fluid passage and a second fluid passage. The method also includes directing a first portion of the auxiliary fluid axially forward through a first fluid passage of the auxiliary passage toward the distal end of the body of the nozzle, directing a second portion of the auxiliary fluid through a second fluid passage of the auxiliary passage inward toward the primary fluid in the primary passage, and mixing the second portion of the auxiliary fluid with the primary fluid in the primary passage to generate a mixed processing fluid.

[0009] In yet another aspect, a nozzle for a laser processing head for processing a workpiece is provided. The nozzle includes a primary passageway disposed within a body of the nozzle. The primary passageway is configured to direct a laser beam and a primary fluid from a proximal end of the body to a distal end of the body for processing the workpiece. The nozzle also includes at least one set of auxiliary passageways disposed within the body of the nozzle. A distal portion of the at least one auxiliary passageway is configured to branch into two fluid passageways, including: (i) a first fluid passageway configured to direct a first portion of the auxiliary fluid axially forward toward the distal end of the body of the nozzle to substantially cover the laser beam exiting the primary passageway; and (ii) a first fluid passageway configured to direct a first portion of the auxiliary fluid axially forward toward the distal end of the body of the nozzle to substantially cover the laser beam exiting the primary passageway. The nozzle also includes at least one set of vent passageways extending outward from the primary passageway and fluidly connecting the primary passageway to the atmosphere.

[0010] Any of the above aspects can include one or more of the following features: In some embodiments, the first fluid passage directs a first portion of the secondary fluid in a forward direction toward the distal end of the body, and the second fluid passage directs a second portion of the secondary fluid in a partial or substantially reverse direction (e.g., substantially axially opposite the direction of the primary fluid in the primary passage) toward the proximal end of the body. In some embodiments, the second fluid passage is angled between about 15 degrees and about 75 degrees relative to the first fluid passage. In some embodiments, the primary fluid and the secondary fluid are gases.

[0011] In some embodiments, the set of at least one auxiliary passage includes at least three separate auxiliary passages circumferentially arranged around the primary passage within the body of the nozzle. In some embodiments, at least one auxiliary passage has a rectangular cross section. In some embodiments, the primary passage has a cross section of 0.78 mm. 2 ~19.6mm 2 The auxiliary passage has a cross-sectional area of ​​5.5 mm 2 ~40mm 2 In some embodiments, the ratio of the cross-sectional area of ​​the primary passage to the cross-sectional area of ​​the auxiliary passage is less than about 8.

[0012] In some embodiments, a set of at least one vent passage is provided extending outward from the primary passage and fluidly connecting the primary passage to the atmosphere. In some embodiments, the at least one vent passage is oriented substantially perpendicular to at least one of the first fluid passages of the primary passage or the at least one auxiliary passage. In some embodiments, the at least one vent passage is axially distal to the second fluid passage. In some embodiments, the at least one vent passage is fluidly isolated from the first fluid passage.

[0013] In some embodiments, the nozzle is a double nozzle including an inner body and an outer body, where (i) the inner body includes a second fluid passage, and (ii) the outer body cooperates with the inner body to form a first fluid passage. In some embodiments, the nozzle is a triple nozzle, further including an insert disposed within the inner body. In some embodiments, the insert is disposed within the primary passage adjacent to a proximal end of the nozzle body. In some embodiments, the insert includes at least one leg, an inner orifice, and a set of shower holes disposed around the inner orifice. In some embodiments, a mixing chamber is disposed within the primary passage between the inner orifice of the insert and the outlet orifice of the nozzle. The mixing chamber is in fluid communication with the first fluid passage of the auxiliary passage. In some embodiments, a vent chamber is disposed between the mixing chamber and the outlet orifice, the vent chamber having a volume smaller than the volume of the mixing chamber.

[0014] In some embodiments, the laser beam is directed axially forward through the primary passage, and the laser beam is emitted with the mixed processing fluid from the primary passage at the distal end of the nozzle. In some embodiments, a first portion of the auxiliary fluid is injected from a first flow path of the auxiliary passage at the distal end of the nozzle to substantially cover the laser beam as it exits the primary passage.

[0015] In some embodiments, the primary fluid has a pressure of about 60 pounds per square inch (psi) (413.69 kPa) to about 300 psi (2068.43 kPa) when it enters the primary passageway at the proximal end of the nozzle. In some embodiments, the secondary fluid has a pressure of about 30 psi (413.69 kPa) to about 300 psi (2068.43 kPa) when it enters the secondary passageway at the proximal end of the nozzle.

[0016] In some embodiments, the primary fluid is constricted prior to mixing the primary fluid with the second portion of the secondary fluid, hi some embodiments, the mixed processing fluid is constricted prior to expelling the mixed processing fluid from the primary passage.

[0017] In yet another aspect, a method for mixing at least two fluids in a nozzle for a laser processing head of a laser processing system is provided, the method including directing a primary fluid axially forward through a primary passage disposed within a body of the nozzle from a proximal end to a distal end of the body, supplying a secondary fluid into at least one secondary passage disposed within the body of the nozzle, directing at least a portion of the secondary fluid through the secondary passage inward toward the primary fluid in the primary passage, and mixing at least a portion of the secondary fluid with the primary fluid in the primary passage to produce a mixed processing fluid.

[0018] In yet another aspect, a nozzle for a laser processing head for processing a workpiece is provided. The nozzle includes a body, a primary passageway disposed within the body, and at least one auxiliary passageway disposed within the body. The primary passageway is configured to direct a laser beam and a primary fluid from a proximal end of the body to a distal end of the body. The at least one auxiliary passageway is configured to direct at least a portion of the auxiliary fluid toward a path of the primary fluid to mix the portion of the auxiliary fluid with the primary fluid within the body of the nozzle.

[0019] In some embodiments, the distal portion of the auxiliary passage is configured to bifurcate into a first fluid passage and a second fluid passage. In some embodiments, the second portion of the auxiliary fluid is directed axially forward through the first fluid passage of the auxiliary passage toward the distal end of the nozzle body. In some embodiments, at least a portion of the auxiliary fluid is directed inward toward the primary fluid by the second fluid passage of the auxiliary passage.

[0020] In some embodiments, directing at least a portion of the secondary fluid inwardly includes directing at least a portion along a direction substantially axially opposite a direction of the primary fluid in the primary passageway. In some embodiments, the second fluid passageway is angled between about 15 degrees and about 75 degrees relative to the first fluid passageway. [Brief explanation of the drawings]

[0021] The above-mentioned advantages of the present invention, together with further advantages, may be better understood by reference to the following description taken in conjunction with the accompanying drawings, in which the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. [Figure 1] 1 is a cross-sectional side view of an exemplary nozzle for a laser processing system, according to some embodiments of the present invention. [Figure 2] 2 is a cross-sectional side view of the nozzle of FIG. 1 from another angle, according to some embodiments of the present invention. [Figure 3a-3b] 3A-3C are plan cross-sectional views of the nozzle of FIGS. 1 and 2 taken at various planes perpendicular to the longitudinal axis A of the nozzle, according to some embodiments of the present invention. [Figure 3c-3d] 3A-3C are plan cross-sectional views of the nozzle of FIGS. 1 and 2 taken at various planes perpendicular to the longitudinal axis A of the nozzle, according to some embodiments of the present invention. [Figure 4] 3A-3C illustrate exemplary flow patterns of primary and secondary / auxiliary fluids through the nozzles of FIGS. 1 and 2, according to some embodiments of the present invention. [Figure 5] 3A-3C illustrate exemplary methods for mixing primary and secondary fluids in the nozzle of FIGS. 1 and 2, according to some embodiments of the present invention. [Figure 6a] FIG. 6 illustrates an exemplary pressure profile 600 within the nozzle 100 of FIGS. 1 and 2 during a laser cutting process, according to some embodiments of the present invention. [Figure 6b]FIG. 6 illustrates an adjusted version of an exemplary pressure profile 600 within the nozzle 100 of FIGS. 1 and 2 during a laser cutting process, according to some embodiments of the present invention. [Figure 7] FIG. 3 illustrates an exemplary computational fluid dynamics (CFD) pressure profile for the nozzle of FIGS. 1 and 2 during a laser cutting process, according to some embodiments of the present invention. [Figure 8] FIG. 2 is a cross-sectional side view of another exemplary nozzle for a laser processing system, according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] 1 shows a side cross-sectional view of an exemplary nozzle 100 for a laser processing system, according to some embodiments of the present invention. As shown, nozzle 100 comprises a body having a proximal end 102 and a distal end 104 along a central longitudinal axis A of the body, with distal end 104 defined as the end closest to a workpiece 126 during operation of the laser processing system, and proximal end 102 opposite distal end 104 along longitudinal axis A.

[0023] A primary passageway 106 is disposed within the body of the nozzle 100 and extends substantially along a central longitudinal axis A between a proximal opening 107 at the proximal end 102 of the nozzle body and a distal opening 109 at the distal end 104 of the nozzle body. The primary passageway 106 is configured to receive a primary fluid (e.g., a gas, a liquid, or a mixture of both) through its proximal opening 107 and to deliver a laser beam, along with a mixture of the primary fluid and at least one auxiliary fluid, to a workpiece 126 (e.g., a metal) through its distal opening 109 for processing the workpiece 126. In some embodiments, an internal mixing chamber 112 is disposed along the primary passageway 106 between the proximal opening 107 and the distal opening 109 of the primary passageway 106.

[0024] As shown, at least one set of auxiliary passages 108 is disposed within the body of the nozzle 100, with each auxiliary passage 108 having a proximal opening 110 radially offset from the longitudinal axis of the primary passage 106. Each auxiliary passage 108 is configured to direct an auxiliary fluid (e.g., gas, liquid, or a mixture of both) through the nozzle 100 for processing the workpiece 126. In some embodiments, each auxiliary passage 108 is in fluid communication with a circumferential auxiliary fluid chamber 150 disposed within the nozzle body to substantially surround the primary passage 106. The circumferential auxiliary fluid chamber 150 is configured to receive the auxiliary fluid from the set of one or more auxiliary passages 108 and split the auxiliary fluid between a set of one or more forward auxiliary passages 108a and a set of one or more reverse auxiliary passages 108b. Thus, the distal portion of each auxiliary passageway 108 branches into at least one of a set of forward fluid passageways 108a and at least one of a set of reverse fluid passageways 108b.

[0025] Each forward auxiliary passage 108a is configured to direct a portion of the auxiliary fluid (received from the auxiliary passage(s) 108) axially forward toward the distal end 104 of the body of the nozzle 100. The forward auxiliary passage(s) 108a can eject the auxiliary fluid from the nozzle 100 through respective distal openings 111 in the distal end 104 of the nozzle body to substantially shroud the laser beam and mixed fluid exiting the primary passage 106 through the distal openings 109 of the primary passage 106.

[0026] Each reverse auxiliary passage 108b has an inlet 120 in fluid communication with a circumferential auxiliary fluid chamber 150 (which fluidly connects the reverse auxiliary passage 108b with the set of main auxiliary passages 108 and the set of forward auxiliary passages 108a) and an outlet 122 in fluid communication with the mixing chamber 112 of the primary passage 106. Each reverse auxiliary passage 108b is configured to direct another portion of the auxiliary fluid (received from the auxiliary passage(s) 108) radially inward to mix with the primary fluid in the mixing chamber 112 of the primary passage 106.

[0027] In some embodiments, the mixing chamber 112 of the primary passage 106 is located axially proximal to the circumferential auxiliary fluid chamber 150, where the main auxiliary passage 108 splits into a forward auxiliary passage 108a and a reverse auxiliary passage 108b. Thus, each reverse auxiliary passage 108b may be configured to direct the auxiliary fluid inward toward the primary passage 106 while directing the auxiliary fluid to the mixing chamber 112 in a direction substantially opposite to the flow of fluid within the primary passage 106. In some embodiments, each reverse auxiliary passage 108b maintains an angle 113 (shown as an inset in FIG. 1 ) of between about 0 degrees and about 90 degrees, e.g., between about 15 degrees and about 75 degrees, relative to the forward auxiliary passage 108a. This reverse flow configuration of the reverse auxiliary passages 108b is advantageous because it can improve the mixing characteristics of the primary and auxiliary fluids within the mixing chamber 112, given the limited space present within the nozzle 100. In some embodiments, reverse flow through each reverse auxiliary passage 108b is achieved by manipulating the relative fluid pressure at the proximal opening 107 of the primary passage 106 and / or the proximal opening 110 of each auxiliary passage 108. In some embodiments, the combined area of ​​the proximal openings 110 of all of the auxiliary passages 108 in the nozzle 100 can be greater than the combined area of ​​the inlets 120 of the reverse auxiliary passages 108b, thereby allowing the fluid flow in the primary auxiliary passage 108 to fully supply auxiliary fluid to both the forward auxiliary passage 108a and the reverse auxiliary passage 108b.

[0028] In some embodiments, the mixing chamber 112 is configured to substantially mix the primary fluid received from the proximal opening 107 of the primary passageway 106 with the secondary fluid received from the set of reverse secondary passageway(s) 108b to produce a mixed fluid. The mixed fluid is then constricted as it flows distally through the primary passageway 106 and is ejected (along with the laser beam) from the nozzle 100 through the distal opening 109 of the primary passageway 106 to contact and process the workpiece 126. In some embodiments, the mixing of the primary fluid and secondary fluid in the mixing chamber 112 occurs within the cutting head of the laser processing system, within 2 feet (60.96 centimeters) of the nozzle bore 145 proximate to the workpiece 126.

[0029] In some embodiments, two separate fluid supply lines 114, 116 are in fluid communication with the proximal opening 107 of the primary passageway 106 and with respective proximal openings 110 of the set of one or more auxiliary passageways 108 to deliver two separate fluids (e.g., gases) to each type of passageway within the nozzle 100. More specifically, the fluid supply line 114 can supply a primary fluid to the primary passageway 106 via the proximal opening 107. The fluid supply line 116 can supply an auxiliary fluid to the set of one or more auxiliary passageways 108 via respective proximal openings 110. In some embodiments, one or both of the primary fluid and the auxiliary fluid are gases. Exemplary primary fluids include nitrogen, oxygen, air, argon, methane, hydrogen, etc. The primary fluid and the auxiliary fluid may be the same or different. In some embodiments, the fluid supply lines 114, 116 are independently controlled to provide fluid flows having independent flow parameters, such as pressure, flow velocity, and / or flow rate. By way of example, supply line 114 may supply primary fluid at a pressure of about 60 pounds per square inch (psi) (413.69 kPa) to about 300 psi (2068.43 kPa) as it enters primary passageway 106 via proximal openings 107. Supply line 116 may supply secondary fluid at a pressure of about 30 pounds per square inch (psi) (206.84 kPa) to about 300 psi (2068.43 kPa) as it enters set of one or more secondary passageways 108 via respective proximal openings 110. As discussed above, nozzle 100 may be configured to mix these fluids (e.g., in mixing chamber 112 of primary passageway 106) at the appropriate concentrations to achieve the desired cutting process with the laser processing system. In some embodiments, one or more of the auxiliary passages 108a, 108b and the primary passage 106 are shaped to induce a pressure drop in the fluid flow through the nozzle 100, such as between the proximal end 102 and the distal end 104 of the nozzle 100, and / or to adjust the characteristics of the fluid flow (e.g., pressure value, flow rate, etc.).

[0030] In some embodiments, one or more of the auxiliary passages 108a, 108b and the primary passage 106 are in communication with the ambient environment (e.g., in contact with air outside the nozzle assembly 100) via one or more vent passages 124 located upstream from the distal opening 109 of the primary passage 106. In some embodiments, the set of one or more vent passages 124 is isolated from direct interaction with the forward auxiliary passage(s) 108a. Furthermore, the vent passages 124 can control one or more characteristics, such as static pressure, flow rate, and / or mixture concentration, of the primary passage 106 and the auxiliary passages 108a, 108b when the primary passage 106 and the auxiliary passages 108a, 108b are supplied with the same or different fluids at the same or different operating parameters (e.g., operating pressures).

[0031] 1 illustrates an exemplary configuration of the nozzle 100 that includes at least one set of vent passages 124 extending outward from the primary passage 106 to fluidly connect the primary passage 106 to an environment (e.g., atmosphere) external to the nozzle 100. This allows a positive fluid flow pressure to be maintained within the primary passage 106 even when the pressure between the nozzle 100 and the workpiece 126 tends to zero, as described in more detail below. As illustrated, each vent passage 124 may be connected to and extend outward from a vent chamber 128 of the primary passage 106 that is distal to the mixing chamber 112 (and the set of reverse auxiliary passages 108b) but proximal to the distal opening 109 of the primary passage 106. Additionally, each vent passage 124 may be positioned axially distal (i.e., downstream) from the mixing chamber 112 and / or the reverse auxiliary passages 108b. In some embodiments, the vent chamber 128 has a volume that is smaller than the volume of the mixing chamber 112. Each vent passageway 124 may be oriented substantially perpendicular to at least one of the primary passageway 106 or the forward auxiliary passageway 108a (both of which may extend substantially parallel to the longitudinal axis A). While the vent passageways 124 in FIG. 1 are shown projecting perpendicular to the longitudinal axis A, the vent passageways 124 may also be inclined or angled relative to the longitudinal axis A. In some embodiments, the vent passageways 124 are positioned axially proximal to the reverse auxiliary passageway(s) 108b, rather than axially distal to the reverse auxiliary passageway(s) 108b as shown.

[0032] In some embodiments, each vent passage 124 can be fluidly isolated / separated from the forward auxiliary passage 108a, allowing only the primary passage 106 and / or the reverse auxiliary passage 108b to communicate with the ambient environment. FIG. 2 shows another side cross-sectional view of the nozzle 100 of FIG. 1, in accordance with some embodiments of the present invention. Both FIGS. 1 and 2 show two perspective cross-sectional views of the same vented nozzle 100, with FIG. 2 rotated about the longitudinal axis A to a position without the vent passages 124. The angle of rotation is approximately 22.5 degrees from FIG. 1 to FIG. 2. FIG. 2 clearly shows that the forward auxiliary passage 108a is not in fluid communication with the vent passage 124. However, in alternative embodiments, the vent passage 124 can extend or protrude from the forward auxiliary flow path 108a in addition to or instead of the primary passage 106.

[0033] In some embodiments, the nozzle 100 of FIGS. 1 and 2 is a triple nozzle consisting of an insert 130, an inner body 132, and an outer body 134. The three layers can be concentrically nested, with the insert 130 disposed substantially inside the inner body 132 and the combination disposed substantially inside the outer body 134. In some embodiments, the insert 130 includes at least one leg 136 oriented inward at an angle 137 and an inner orifice 138. In some embodiments, the insert 130 further includes a set of shower holes (not shown) disposed about the inner orifice 138. The insert 130 can be positioned within the primary passage 106 adjacent the proximal end 102 of the nozzle 100. Additionally, the mixing chamber 112 is positioned within the primary passage 106 between the inner orifice 138 of the insert 130 and a distal opening 109 of the primary passage 106. In some embodiments, the inner body 132 forms at least a portion of the primary passage 106. In some embodiments, the reverse auxiliary passages 108b are disposed in the inner body 132 such that each reverse auxiliary passage 108b extends from the inner surface to the outer surface of the inner body 132. In some embodiments, the inner body 132 and the outer body 134 cooperate to form a forward auxiliary passage 108a therebetween. In some embodiments, the nozzle 100 is configured as a double nozzle with the insert 130 removed, thus including only the inner body 132 and the outer body 134. In some embodiments, advanced manufacturing methods, such as 3D printing, are utilized to achieve similar geometries and geometric features in a single-piece construction. In some embodiments, as shown in FIG. 2, the nozzle 100 includes alignment features 155 on the body of the nozzle 100 to provide installation alignment references to enable optimized alignment with the nozzle bore 145.

[0034] In some embodiments, the vent passages 124 are compatible with the dual or triple design of the nozzle 100. The vent passages 124 allow for a substantially larger design window for the inner and outer nozzle bodies 132, 134 in size, pressure, and more uniform flow as the distance between the nozzle 100 and the workpiece 126 changes. In some embodiments, the vent passages 124 allow the fluid flow velocity to remain positive within the nozzle 100 even as the nozzle-to-workpiece distance approaches zero. To maintain a positive pressure, a larger overall volume of fluid (e.g., the combination of primary and secondary fluids) must be supplied to the nozzle 100; this increased fluid supply can be provided by auxiliary fluid supplied to the auxiliary passages 108 using less expensive fluids. Additionally, the vent passages 124 help prevent negative axial pressure gradients within the flow path as the gap distance between the distal end 104 of the nozzle 100 and the workpiece 126 decreases. Negative axial pressure gradients are generally undesirable because they can cause fluid to backflow into one or more flow paths, causing material sputter onto the nozzle 100 or clog the flow paths, or worse, contaminate the laser optics, significantly reducing their lifespan and processing stability.

[0035] 3a-3d show plan cross-sectional views of the nozzle 100 of FIGS. 1 and 2 taken at various planes perpendicular to the longitudinal axis A of the nozzle 100, according to some embodiments of the present invention. As shown in FIG. 3a, which is a cross-sectional view of the nozzle 100 taken at the radial plane D-D' shown in FIG. 1, the nozzle 100 can include 16 auxiliary passages 108 arranged circumferentially around a central primary passage 106. In some embodiments, the primary passages 106 are spaced apart from each other by approximately 0.78 mm. 2 ~Approx. 19.6mm 2 In some embodiments, each of the auxiliary passages 108 has a cross-sectional area of ​​about 0.55 mm 2 ~approx. 40mm 2In some embodiments, the ratio of the cross-sectional area of ​​the primary passage 106 to the cross-sectional area of ​​a single auxiliary passage 108 is less than about 8. As an example, the diameter of each of the 16 auxiliary passages 108 may be about 1.5 mm, with the total area of ​​all 16 auxiliary passages being about 28.3 mm. 2 (16*π*0.85mm*0.85mm). In alternative embodiments, the nozzle 100 may include fewer or more auxiliary passages 108, such as 3, 6, or 24 auxiliary passages 108.

[0036] In some embodiments, as shown in Figure 3b, which is a cross-sectional view of the nozzle 100 taken through the radial plane C-C' shown in Figure 1, the nozzle 100 can include eight reverse auxiliary passages 108b in fluid communication with a circumferential auxiliary chamber 150 that is also connected to the sixteen main auxiliary passages 108. In some embodiments, each reverse auxiliary passage 108b has a diameter of about 1.2 mm, and the total area of ​​all eight reverse auxiliary passages 108b is about 9 mm. 2 (8*π*0.6mm*0.6mm). Thus, in the configuration of nozzle 100 shown in Figures 3a-3d, the total area of ​​the main auxiliary passages 108 is much greater than the total area of ​​the reverse auxiliary passages 108b. In alternative embodiments, nozzle 100 may include fewer or more reverse auxiliary passages 108b, such as four or sixteen reverse auxiliary passages 108b.

[0037] In some embodiments, as shown in Figure 3c, which is a cross-sectional view of the nozzle 100 taken through the radial plane B-B' shown in Figure 1, the nozzle 100 may include a set of eight vent passages 124 extending outward from the vent chamber 128 of the primary passage 106 to fluidly connect the primary passage 106 to the atmosphere. In general, there may be more or fewer vent passages 124 of different shapes, sizes, or spacings as needed to achieve the desired operating flow velocity and pressure profiles in the primary and secondary fluids. As shown, the vent passages 124 are fluidly isolated from the forward auxiliary passage 108a.

[0038] In some embodiments, as shown in Figure 3d, which is a cross-sectional view of nozzle 100 taken through radial plane A-A' shown in Figure 1, nozzle 100 may include a set of eight forward auxiliary passages 108a distributed about primary passage 106. In alternative embodiments, nozzle 100 may include fewer or more forward auxiliary passages 108a, such as four or sixteen forward auxiliary passages 108b. Although Figures 3a-3d depict primary passage 106, auxiliary passages 108, forward auxiliary passages 108a, reverse auxiliary passages 108b, and vent passage 124 as having circular cross-sections, in alternative embodiments, these passages may have different cross-sectional shapes, such as rectangular cross-sections.

[0039] FIG. 4 illustrates an exemplary flow pattern of a primary fluid and a secondary / auxiliary fluid through the nozzle 100 of FIGS. 1 and 2 , according to some embodiments of the present invention. FIG. 5 illustrates an exemplary method 500 for mixing a primary fluid and an auxiliary fluid within the nozzle 100 of FIGS. 1 and 2 , according to some embodiments of the present invention. The method 500 of FIG. 5 will be described in the context of the fluid flow pattern shown in FIG. 4 . In step 502 of method 500, a primary fluid is directed to a proximal opening 107 of a primary passage 106 of the nozzle 100, which is located at the proximal end 102 of the nozzle body. The primary fluid may be supplied from an input line 114. The primary fluid is adapted to flow axially forward (along path 402 of FIG. 4 ) through the primary passage 106 toward a mixing chamber 112 of the primary passage 106. In step 504, the auxiliary fluid is directed to a proximal opening 110 of each auxiliary passage 108 in a set of one or more auxiliary passages 108 arranged within the nozzle body around the primary passage 106. The auxiliary fluid may be supplied from an input line 116 that is controllable and actuable independently from the primary input line 114. The auxiliary fluid flows axially forward (along path 404 in FIG. 4 ) through each of the one or more auxiliary passages 108 toward the circumferential auxiliary fluid chamber 150. Upon reaching the circumferential auxiliary fluid chamber 150, the auxiliary fluid supplied by the set of one or more auxiliary passages 108 branches / divides into a set of forward fluid passages 108 a and a set of one or more reverse fluid passages 108 b.

[0040] In step 506, a portion of the auxiliary fluid provided by the set of auxiliary passages 108 is directed by each of the reverse fluid passages 108b to flow radially inward (along path 408 in FIG. 4 ) toward the primary fluid in the mixing chamber 112 of the primary passage 106. For example, the reverse auxiliary passages 108b may direct the auxiliary fluid radially inward into the path of the primary fluid along a direction substantially axially opposite (i.e., axially reverse) to the direction of flow of the primary fluid in the primary passage 106. In step 508, the mixing chamber 112 is configured to mix a portion of the auxiliary fluid received from one or more reverse fluid passages 108b with the primary fluid in the primary passage 106 to generate a mixed processing fluid (mixture 410 in FIG. 4 ). In some embodiments, the primary fluid in the primary passage 106 is constricted before being mixed with the auxiliary fluid. For example, the inner orifice 138 of the insert 130 may impart a constriction to the primary fluid as it enters the primary passage 106. In some embodiments, the mixed processing fluid is directed axially forward (along path 412 in FIG. 4 ) through the primary passage 106 along with a laser beam (not shown) of a laser processing system. The combination of the mixed processing fluid and the laser beam may be emitted from the primary passage 106 through a distal opening 109 of the primary passage 106 to reach the workpiece 126 for processing the workpiece 126. In some embodiments, the mixed processing fluid is constricted before being ejected from the primary passage 106. For example, such constriction may be provided by constricting a nozzle bore 145 in the primary passage 106 adjacent the distal opening 109 of the primary passage 106.

[0041] In step 510, another portion of the auxiliary fluid provided by the set of auxiliary passages 108 is directed by each of the forward fluid passages 108a to flow axially in a forward direction (along path 406 in FIG. 4 ) toward the distal end 104 of the nozzle body. This portion of the auxiliary fluid may be ejected from the forward fluid passages 108a through their respective distal openings 111 to substantially cover the laser beam and the mixed processing fluid (e.g., as a shroud or shield gas) as they exit the distal openings 109 of the primary passages 106. As shown in FIG. 4 , the path 406 of the auxiliary fluid flow in the forward auxiliary passages 108a may be substantially parallel to the path 412 of the mixed fluid and laser beam flow in the primary passage 106.

[0042] In some embodiments, a portion of the mixed processing fluid in the primary passageway 106 is vented to the atmosphere through a set of one or more radial vent passageways 124 (along path 414 in FIG. 4 ) before the mixed fluid is ejected from the nozzle 100 through the distal opening 109. Each vent passageway 124 may be connected to and extend outwardly from a vent chamber 128 of the primary passageway 106 distal to the mixing chamber 112. In some embodiments, the vented portion of the mixed processing fluid is fluidically isolated from the auxiliary fluid in the forward fluid passageway(s) 108 a. Thus, paths 406 and 414 are fluidically isolated from each other.

[0043] In general, the direction of fluid flow through the nozzle 100 (e.g., through the vent passage 124, the forward passage 108a, and the reverse passage 108b) depends on the relative pressures of the primary and secondary fluids provided at their respective proximal openings 107, 111, as well as their relative geometric characteristics (e.g., the size, number, location, angle, induced pressure drop, etc.) of the passage openings. These operating parameters and geometric characteristics can be controlled and adjusted as appropriate to achieve desired cutting results. In some embodiments, the nozzle 100 is described in connection with two fluids (i.e., a primary fluid and a secondary fluid), but those skilled in the art will appreciate that the nozzle 100 can readily be designed to accommodate the flow and mixing of additional fluids, such as tertiary and / or quaternary fluids, and beyond. In various embodiments, the fluids mixed by the nozzle 100 can be liquids, gases, or combinations (e.g., atomized) of one or more gases and one or more liquids. In some embodiments, the nozzle 100 is constructed from the same material. Alternatively, the nozzle 100 can utilize multiple materials or components to achieve a desired result.

[0044] In some embodiments, such mixing of processing fluids within the nozzle 100 as described above may occur at different locations in the laser processing system, such as in or around the nozzle holder. For example, a portion of the auxiliary fluid may be introduced and / or mixed with the primary fluid stream within about 2 feet (60.96 centimeters) of the nozzle bore 145 (e.g., near the workpiece, inside the cutting head, etc.). In these embodiments, a portion of the auxiliary fluid may be introduced or injected into the primary fluid stream via features in the cutting head, the nozzle holder, and / or the nozzle 100 itself. In some embodiments, a first portion of the auxiliary fluid stream is introduced into the primary fluid stream within the cutting head, a second portion of the auxiliary stream is introduced into the primary fluid stream via features (e.g., passages / holes) in the nozzle holder, and a third portion of the auxiliary stream is introduced into the primary fluid stream via features in the nozzle 100. This staged introduction promotes mixing of the fluids. In some other embodiments, the auxiliary fluid is introduced in only one of these stages. In some embodiments, a secondary fluid (eg, secondary, tertiary, quaternary, etc.) is introduced into or mixed with the primary fluid proximate an optical surface (eg, a laser lens).

[0045] Generally, the various embodiments of the nozzle 100 described herein have several advantages, including the creation of a mixing region (e.g., mixing chamber 112) that mixes the auxiliary fluid with the primary fluid in proximity to the workpiece 126 (e.g., within 2 feet (60.96 centimeters) of the workpiece 126). The auxiliary fluid is provided by the outer auxiliary passage 108 and flows radially inward through the nozzle 100 to mix with the primary fluid in the mixing region of the inner primary passage 106 before being discharged through the distal opening 109 of the primary passage 106. Such passive mixing reduces and / or eliminates the need to set up expensive and large mixing systems employed in existing laser processing systems. Another advantage includes better control of pressure within the different passages of the nozzle 100. Venting within the nozzle 100 creates flow characteristics that allow the mixing region to mix the primary and secondary fluids. Although vented nozzles generally consume more fluid overall than non-vented nozzles, the nozzle designs described above using auxiliary passages 108 and auxiliary fluids can support and reduce the use of primary fluid, which is typically more expensive than the auxiliary fluid. More specifically, the auxiliary passages can form a sheath of auxiliary fluid around the generally more expensive primary fluid. This configuration enhances robust processing while using the minimum amount of primary fluid necessary for the required processing task.

[0046] Yet another benefit includes reduced costs associated with mixing fluids in the nozzle designs described above. For laser processing, air can be the least expensive assist gas to use, since it typically requires only electricity for processing, as well as a compressor and filtration components to remove moisture, oil, and particulates. Nitrogen and oxygen are the next lowest-cost options, but due to the high flow rates required for high-pressure laser processing, their associated operating costs can still be a major factor in consumable costs. As an example, liquid nitrogen is commonly used to provide assist gas for laser processing, flowing at about 50 to about 100 standard cubic feet per minute (SCFM) (approximately 1.416 m).3 / min ~ 2.832m 3 This can require a flow rate of up to 1 / min. With a nominal price of liquid nitrogen of $1 / liter, this translates to an operating cost of $122 to $244 per hour of consumption. Furthermore, if the total nitrogen concentration is at an appropriate level, the amount of burr at the bottom of the cutting edge can be reduced or eliminated, depending on the specific material. However, in this case, the majority of the gas consumed is still nitrogen, which, along with expensive equipment for mixing the gases in the appropriate ratio, leads to high operating costs. Additionally, as laser power continues to increase, the demands on optical components and their cleanliness also increase. The air used in the gas mixture comes into contact with the optical components, requiring significant maintenance for air filters. By implementing a system and method for mixing gases within the nozzle of the present technology, such as using nitrogen as the primary fluid and air as the auxiliary fluid, the consumption rate of nitrogen and / or oxygen can be significantly reduced because the correct mixture concentration is only needed in a small processing zone (e.g., mixing chamber 112) and the remaining bulk flow can be made up of lower-cost air (e.g., auxiliary fluid). Additionally, high purity nitrogen (e.g., primary fluid) can be introduced only to the area in contact with the optical components to maintain cleanliness, while lower quality air (e.g., secondary fluid) can be utilized to supply the nozzle to be used for mixing. As an example, the required nitrogen flow rate in a mixing nozzle has been measured to be 9-12 SCFM (0.2549 m). 3 / min~0.3398m 3 / min), a reduction of over 80% from conventional flow rates and savings of up to $195 / hr. Thus, significant benefits are realized by mixing air and nitrogen at high nitrogen concentrations within a small treatment zone compared to using either nitrogen or air alone.

[0047] 6a and 6b show an exemplary pressure profile 600 and an adjusted version of the pressure profile 600, respectively, within the nozzle 100 of FIGS. 1 and 2 during a laser cutting process, according to some embodiments of the present invention. A secondary fluid, provided via supply line 116 in the form of a gas such as oxygen or air (represented in blue), can be mixed with a primary fluid, provided via supply line 114 in the form of a gas such as nitrogen (represented in red), to support the flow of the primary gas and alter the chemical process within the processing region 602. The added support allows for a combination of flow profiles and gas compositions to optimize cutting parameters and minimize operating costs. As seen in FIG. 6a, the primary and auxiliary gases are first supplied from different sources via supply lines 114 and 116 and then mixed within the mixing chamber 112 of the nozzle 100, after which the mixture flows into the processing region 602 along with the laser beam. Gas mixing can aid the cutting process, for example, by treating the primary supply gas with oxygen before it reaches the workpiece 126 and / or by creating a gas mixture with the appropriate concentration depending on the primary and auxiliary gas and / or fluid species being used. Figure 6b is a detailed view of the pressure profile 600 of Figure 6a, narrowing the concentration range to show a tailored concentration 603 of about 80% to about 90% in the critical processing zone. In some applications, oxygen treatment of the primary supply gas can be beneficial because oxygen often reacts exothermically with the material being cut, which can lead to increased cutting speeds while favorably changing other thermophysical properties such as melt viscosity and surface tension. As is commonly understood, different gases have different cutting characteristics depending on the material being cut.

[0048] FIG. 7 illustrates an exemplary computational fluid dynamics (CFD) pressure profile 700 for the nozzle 100 of FIGS. 1 and 2 during a laser cutting process, according to some embodiments of the present invention. As illustrated, the use of the vent passages 124 allows for higher pressures around the peripheral regions of the nozzle 100 compared to the central region. This control allows users to individually modify the pressure in each of the peripheral and central regions by appropriately sizing the various passages within the nozzle 100 and / or adjusting the flow rates / pressures of the secondary and / or primary fluid flows. Traditionally, it has been difficult to provide higher peripheral pressures without increasing the nozzle's central pressure. The improved control provided by the vented nozzle design described above allows for optimization of the flow rate and pressure profiles for a given processing operation. However, one issue that can arise with different pressure regions within a nozzle is the possibility of backflow from the high-pressure region to the low-pressure region. This issue is particularly detrimental when backflow exists in the central flow region (e.g., the primary passages 106) because it increases the risk of optical contamination. This problem is avoided in vented nozzle 100 by adding vent passage 124 which diverts excess pressure and still allows positive flow from the central flow region through inner orifice 138 .

[0049] 8 shows a side cross-sectional view of another exemplary nozzle 500 for a laser processing system, according to some embodiments of the present invention. As shown, the nozzle 500 comprises a body having a proximal end 502 and a distal end 504, where the distal end 504 is defined as the end closest to a workpiece 526 during operation of the laser processing system, and the proximal end 502 is opposite the distal end 504 along a longitudinal axis A.

[0050] A primary passageway 506 is disposed within the body of the nozzle 500. The primary passageway 506 is configured to receive a primary fluid 510 (e.g., a gas, a liquid, or a mixture of both) through its proximal opening 507. The nozzle body is configured to deliver a laser beam, along with a mixture 514 of the primary fluid and at least one auxiliary fluid, to a workpiece 526 (e.g., a metal) through its distal opening 509 to process the workpiece 526.

[0051] As shown, at least one auxiliary passage 508 is disposed within the body of the nozzle 500. Each auxiliary passage 508 is configured to direct at least a portion of an auxiliary fluid 512 (e.g., a gas, a liquid, or a mixture of both) toward the path of the primary fluid 510 and mix the portion of the auxiliary fluid 512 with the primary fluid 510 within the body of the nozzle before delivering a mixture 514 of the primary fluid and the portion of the auxiliary fluid to the workpiece 526.

[0052] It should be understood that the various aspects and embodiments of the present invention can be combined in various ways. Based on the teachings herein, one of ordinary skill in the art can readily determine how to combine these various embodiments. Those skilled in the art will be able to make modifications upon reading and understanding this specification.

Claims

1. 1. A nozzle for a laser processing head for processing a workpiece, comprising: a primary passage disposed within a body of the nozzle, the primary passage configured to direct a laser beam and a primary fluid from a proximal end of the body to a distal end of the body to machine the workpiece; a set of at least one vent passageway extending outwardly from the primary passageway fluidly connecting the primary passageway to the atmosphere; a set of at least one auxiliary passage disposed within the body of the nozzle and radially offset from a longitudinal axis of the primary passage, a distal portion of the at least one auxiliary passage bifurcating into two fluid passages, the two fluid passages comprising: a first fluid passage configured to direct a first portion of a secondary fluid axially forward toward the distal end of the body of the nozzle to substantially cover the laser beam exiting the primary passage; a second fluid passage configured to direct a second portion of the secondary fluid radially inward to mix with the primary fluid in the primary passage.

2. 2. The nozzle of claim 1, wherein (i) the first fluid passage directs the first portion of the auxiliary fluid in a forward direction toward the distal end of the body, and (ii) the second fluid passage directs the second portion of the auxiliary fluid in a substantially reverse direction toward the proximal end of the body.

3. The nozzle of claim 1 , wherein the second fluid passage is angled between about 15 degrees and about 75 degrees relative to the first fluid passage.

4. The nozzle of claim 1 , wherein the set of at least one auxiliary passage comprises at least three separate auxiliary passages circumferentially arranged around the primary passage within the body of the nozzle.

5. The nozzle of claim 1 , wherein the at least one auxiliary passage has a rectangular cross-section.

6. The nozzle of claim 1 , wherein the at least one vent passage is oriented substantially perpendicular to at least one of the first fluid passages of the primary passage or the at least one auxiliary passage.

7. The nozzle of claim 1 , wherein the at least one vent passage is axially distal to the second fluid passage.

8. The nozzle of claim 1 , wherein the at least one vent passage is fluidly isolated from the first fluid passage.

9. 2. The nozzle of claim 1, wherein the nozzle is a double nozzle including an inner body and an outer body, (i) the inner body including the second fluid passage, and (ii) the outer body cooperating with the inner body to form the first fluid passage.

10. The nozzle of claim 9 , wherein the nozzle is a triple nozzle further including an insert disposed within the inner body.

11. The nozzle of claim 1 , wherein the primary fluid and the secondary fluid are gases.

12. The primary passage is 0.78 mm ２ ~19.6mm ２ The auxiliary passage has a cross-sectional area of ​​5.5 mm ２ ~40mm ２ The nozzle of claim 1 having a cross-sectional area of

13. The nozzle of claim 1 , wherein a ratio of a cross-sectional area of ​​the primary passage to a cross-sectional area of ​​the auxiliary passage is less than about 8.

14. The nozzle of claim 1 , further comprising an insert disposed within the primary passageway adjacent the proximal end of the body of the nozzle.

15. The nozzle of claim 14 , wherein the insert includes at least one leg, an inner orifice, and a set of shower holes disposed about the inner orifice.

16. 16. The nozzle of claim 15, further comprising a mixing chamber disposed in the primary passage between the inner orifice of the insert and an exit orifice of the nozzle, the mixing chamber in fluid communication with the first fluid passage of the auxiliary passage.

17. 17. The nozzle of claim 16, further comprising a vent chamber disposed between the mixing chamber and the exit orifice, the vent chamber having a volume smaller than a volume of the mixing chamber.

18. 1. A method of mixing at least two fluids in a nozzle for a laser processing head of a laser processing system, comprising: directing a primary fluid axially forward through a primary passage disposed within a body of the nozzle from a proximal end to a distal end of the body; supplying a secondary fluid to at least one auxiliary passage disposed in the body of the nozzle, a distal portion of the auxiliary passage configured to bifurcate into a first fluid passage and a second fluid passage; directing a first portion of the auxiliary fluid axially forward through the first fluid passage of the auxiliary passage toward the distal end of the body of the nozzle; directing a second portion of the secondary fluid inwardly through the second fluid passage of the secondary passage toward the primary fluid in the primary passage; mixing the second portion of the secondary fluid with the primary fluid in the primary passage to produce a mixed processing fluid; and venting a portion of the mixed processing fluid to atmosphere through at least one radial vent passage disposed within the body of the nozzle.

19. directing a laser beam axially forward through the primary passage; 20. The method of claim 18, further comprising: emitting the laser beam with the mixed processing fluid from the primary passage at the distal end of the nozzle.

20. 20. The method of claim 19, further comprising ejecting the first portion of the secondary fluid from the first fluid passage of the secondary passage at the distal end of the nozzle to substantially cover the laser beam as it exits the primary passage.

21. 20. The method of claim 18, wherein directing the second portion of the secondary fluid inwardly comprises directing the second portion along a direction substantially axially opposite a direction of the primary fluid within the primary passage.

22. 20. The method of claim 18, wherein the second fluid passage is angled between about 15 degrees and about 75 degrees relative to the first fluid passage.

23. 20. The method of claim 18, wherein the primary fluid has a pressure of about 60 pounds per square inch (psi) (413.69 kPa) to about 300 psi (2068.43 kPa) when entering the primary passageway from the proximal end of the nozzle.

24. 20. The method of claim 18, wherein the auxiliary fluid has a pressure of about 30 psi (413.69 kPa) to about 300 psi (2068.43 kPa) when it enters the auxiliary passage from the proximal end of the nozzle.

25. 20. The method of claim 18, wherein the portion of the discharged mixed processing fluid is fluidly isolated from the first portion of the auxiliary fluid in the first fluid passage.

26. 20. The method of claim 18, further comprising constricting the primary fluid prior to mixing the primary fluid with the second portion of the secondary fluid.

27. The method of claim 18 further comprising constricting the mixed processing fluid before expelling the mixed processing fluid from the primary passage.

28. The method of claim 18 , wherein the primary fluid and the secondary fluid are gases.

29. 1. A nozzle for a laser processing head for processing a workpiece, comprising: a primary passage disposed within a body of the nozzle, the primary passage configured to direct a laser beam and a primary fluid from a proximal end of the body to a distal end of the body to machine the workpiece; a set of at least one auxiliary passageway disposed within the body of the nozzle, a distal portion of the at least one auxiliary passageway configured to branch into two fluid passageways, the two fluid passageways comprising: a first fluid passage configured to direct a first portion of a secondary fluid axially forward toward the distal end of the body of the nozzle to substantially cover the laser beam exiting the primary passage; a second fluid passage configured to direct a second portion of the secondary fluid toward the primary passage to mix with the primary fluid in the primary passage; and and at least one set of vent passages extending outwardly from said primary passages and fluidly connecting said primary passages to the atmosphere.

30. 30. The nozzle of claim 29, wherein the second fluid passage is configured to direct the second portion of the secondary fluid inwardly toward the primary passage and in a direction axially opposite the forward direction of the first fluid passage.

31. 30. The nozzle of claim 29, wherein the second fluid passage is angled between about 15 degrees and about 75 degrees relative to the first fluid passage.

32. 30. The nozzle of claim 29, wherein the at least one vent passage is oriented substantially perpendicular to the primary passage.

33. 30. The nozzle of claim 29, wherein the at least one vent passage is fluidly isolated from the first fluid passage.

34. 1. A method of mixing at least two fluids in a nozzle for a laser processing head of a laser processing system, comprising: directing a primary fluid axially forward through a primary passage disposed within a body of the nozzle from a proximal end to a distal end of the body; providing a secondary fluid into at least one secondary passage disposed within the body of the nozzle; directing at least a portion of the secondary fluid inwardly through the secondary passage toward the primary fluid in the primary passage; mixing the at least a portion of the secondary fluid with the primary fluid in the primary passage to produce a mixed processing fluid; and venting a portion of the mixed processing fluid to the atmosphere through at least one vent passage disposed within the body of the nozzle.

35. 35. The method of claim 34, wherein a distal portion of the auxiliary passage is configured to bifurcate into a first fluid passage and a second fluid passage.

36. 36. The method of claim 35, further comprising directing a second portion of the auxiliary fluid axially forward through the first fluid passage of the auxiliary passage toward the distal end of the body of the nozzle.

37. 36. The method of claim 35, wherein the at least a portion of the secondary fluid is directed inwardly toward the primary fluid by the second fluid passage of the secondary passage.

38. 35. The method of claim 34, wherein directing the at least a portion of the secondary fluid inwardly comprises directing the at least a portion along a direction substantially axially opposite a direction of the primary fluid within the primary passage.

39. 38. The method of claim 37, wherein the second fluid passage is angled between about 15 degrees and about 75 degrees relative to the first fluid passage.

40. 1. A nozzle for a laser processing head for processing a workpiece, comprising: The main body and a primary passageway disposed within the body, the primary passageway configured to direct a laser beam and a primary fluid from a proximal end of the body to a distal end of the body; at least one auxiliary passage disposed within the body, the at least one auxiliary passage configured to direct at least a portion of a secondary fluid into a path of the primary fluid to mix the portion of the secondary fluid with the primary fluid within the body of the nozzle; and at least one set of vent passages extending outwardly from said primary passages and fluidly connecting said primary passages to the atmosphere.

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