Droplet generation mechanism for spray deposition forming

Abstract

The application discloses a kind of melt drop generating mechanism for spray deposition forming, including the molten liquid cylinder being arranged in the center of centrifugal disc, and the liquid outlet is arranged on the cylinder wall of molten liquid cylinder, and piston rod is arranged in molten liquid cylinder;Piston rod can slide up and down, for blocking or opening liquid outlet, so that metal melt in molten liquid cylinder is separated and quantitatively thrown from liquid outlet, and forms melt drop.The rotating molten liquid cylinder can make metal melt produce centrifugal force, and the quantity and volume of metal melt thrown from liquid outlet can be controlled by adjusting the frequency of piston rod sliding up and down, and then the melt drop with nearly consistent diameter is obtained.The melt drop with similar diameter has similar impact kinetic energy and cooling speed, and can form the organizational structure with small grain size and high density.In addition, the application also discloses the relationship between liquid outlet radius, piston rod up-down movement frequency and related parameters, so that the radius of liquid outlet and the frequency of piston rod up-down movement can be inversely calculated according to the spherical radius of melt drop, to provide theoretical basis for controlling the size of melt drop.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of spray deposition forming technology, in particular to a molten drop generating mechanism for spray deposition forming. BACKGROUND

[0002] The principle of spray deposition is to break the molten metal into small molten drops under the protection of inert gas, and then continuously spray the molten drops onto a metal base under the action of high-pressure gas or centrifugal force to form a semi-solid deposition layer, which is solidified into a preform by heat conduction of the metal base. The preform is formed into a high-density metal ring body after hot extrusion or hot forging. The advantage of spray deposition process is that it can prepare ring-shaped parts with small composition segregation, small and uniform structure, and large size.

[0003] The invention patent with the authorized announcement number CN109877299B discloses a centrifugal casting device and a centrifugal disc for centrifugal spray forming. The centrifugal casting device in the patent realizes the preparation of a metal hollow ingot by applying the principle of spray deposition. However, it is found in application that the prepared metal hollow ingot is not ideal, mainly because the grain structure is not fine enough and the density is not high enough. It is found through analysis that the molten drops thrown out of the centrifugal disc have different diameters and are not uniform. The molten drops with a diameter less than 1mm have a short flight distance and small impact kinetic energy, which is not enough to break the internal dendrites by impact. The molten drops with a diameter greater than 3mm have a cooling speed that does not meet the requirements, and they will disperse everywhere after impacting the base. Only the molten drops with a diameter in the range of 1-3mm can break the internal dendrites by impact and will not disperse everywhere. The structure and rotational speed of the centrifugal disc have been improved many times, but the effect is not ideal. Therefore, the generation method of the molten drops needs to be considered from another angle. SUMMARY

[0004] In order to overcome the deficiencies in the background art, the present application discloses a molten drop generating mechanism for spray deposition forming, which aims to:

[0005] To achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0006] A molten drop generating mechanism for spray deposition forming, comprising a molten liquid cylinder arranged at the center of a centrifugal disc, a liquid outlet hole is arranged on the cylinder wall of the molten liquid cylinder, and a piston rod is arranged in the molten liquid cylinder; the piston rod can slide up and down to block or open the liquid outlet hole, so that the metal molten liquid in the molten liquid cylinder is intermittently and quantitatively thrown out of the liquid outlet hole to form molten drops.

[0007] The beneficial effects produced after implementing the above technical solutions are that the rotating molten metal cylinder generates centrifugal force on the metal melt, the amount and volume of the metal melt thrown out of the liquid outlet hole can be controlled by adjusting the frequency of the up-and-down sliding of the piston rod, and thus the molten drops with nearly consistent diameters are obtained. The molten drops with similar diameters have similar impact kinetic energy and cooling speed, and thus the spray deposition parts with small crystal grains and high density can be prepared.

[0008] Further improve the technical solutions, the radius of the liquid outlet hole is r, and the frequency of the up-and-down movement of the piston rod is f, then:

[0009] r=K*Sr,

[0010]

[0011] In the formula, R is the radius of the molten metal cylinder, p is the density of the metal melt, Sr is the spherical radius of the molten drop, w is the rotating speed of the centrifugal disc, s is the surface tension coefficient of the metal melt, and C is greater than or equal to 1.

[0012] The beneficial effects produced after implementing the above technical solutions are that the above formula reveals the relationship between the radius of the liquid outlet hole, the frequency of the up-and-down movement of the piston rod and the related parameters, and the radius of the liquid outlet hole and the frequency of the up-and-down movement of the piston rod can be inversely calculated according to the spherical radius of the molten drop to be obtained, thereby providing a theoretical basis for controlling the size of the molten drop.

[0013] Further improve the technical solutions, the liquid injection pipe is arranged in the piston rod, and the liquid injection pipe is used for injecting the metal melt into the molten metal cylinder.

[0014] The beneficial effects produced after implementing the above technical solutions are that a certain amount of metal melt can be always reserved in the molten metal cylinder.

[0015] Due to the adoption of the above technical solutions, the molten drop generating mechanism further comprises a crank slider mechanism connected with the piston rod and used for driving the piston rod to slide up and down.

[0016] The beneficial effects produced after implementing the above technical solutions are that the crank slider mechanism is a common reciprocating linear motion mechanism, and can drive the piston rod to slide up and down.

[0017] Due to the adoption of the above technical solutions, the horizontal sliding slot is arranged at the upper portion of the piston rod, the eccentric shaft is fitted and arranged in the horizontal sliding slot, and the eccentric shaft is connected with the speed regulation motor; when the speed regulation motor rotates, the piston rod is driven to slide up and down through the cooperation of the eccentric shaft and the sliding slot.

[0018] The beneficial effects produced after implementing the above technical solutions are that the piston rod slides up and down once per revolution of the speed regulation motor, and the frequency of the up-and-down movement of the piston rod can be adjusted by changing the rotating speed of the speed regulation motor.

[0019] A through hole is arranged on the wall of the melt cylinder, and a liquid outlet nozzle is detachably arranged in the through hole. An inner hole in the liquid outlet nozzle is a liquid outlet hole.

[0020] The beneficial effects of the above technical solution are that the radius of the liquid outlet hole can be quickly adjusted by replacing the liquid outlet nozzle. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A three-dimensional structure schematic diagram of the present melt drop generating mechanism in embodiment 1 is shown.

[0022] Figure 2 A cross-sectional structure schematic diagram of the present melt drop generating mechanism is shown. Figure 1

[0023] Figure 3 A structure schematic diagram when the piston rod is ascending is shown.

[0024] Figure 4 A structure schematic diagram when the piston rod is descending is shown.

[0025] Figure 5 A schematic diagram when the melt enters the liquid outlet hole is shown.

[0026] Figure 6 A schematic diagram when the melt is thrown out of the liquid outlet hole is shown.

[0027] Figure 7 A three-dimensional structure schematic diagram of the present melt drop generating mechanism in embodiment 2 is shown.

[0028] Figure 8 A cross-sectional structure schematic diagram of the present melt drop generating mechanism is shown. Figure 7

[0029] Figure 9 A structure schematic diagram of the melt cylinder in embodiment 3 is shown.

[0030] In the figure:

[0031] 1, disc body;

[0032] 2, melt cylinder; 21, liquid outlet hole; 22, liquid outlet nozzle;

[0033] 3, piston rod;

[0034] 4, liquid injection pipe;

[0035] 5, eccentric shaft;

[0036] 6, speed regulation motor;

[0037] 7, melt drop. DETAILED DESCRIPTION

[0038] ​​The preferred embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood that the embodiments are only used to explain the technical principles of the present application, and are not intended to limit the scope of protection of the present application. It should be noted that in the description of the present application, the terms "front", "back", "up", "down", "left", "right", "vertical", "horizontal", "inner", "outer", and other terms indicating the direction or positional relationship are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. It should also be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", and "connection" should be understood broadly, for example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or a connection between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] Embodiment 1

[0040] As shown in Figure 1 , a molten drop generating mechanism for spray deposition forming includes a molten liquid cylinder arranged at the center of a centrifugal disc, and the structure and function thereof will be described below.

[0041] Referring to Figure 2 , the centrifugal disc includes a disc body 1 in the shape of a circle, which can rotate along its axis in a horizontal plane. A molten liquid cylinder 2 is fixed at the center of the disc body 1, and the material of the molten liquid cylinder 2 is a high-temperature-resistant heat-insulating material. A metal molten liquid is contained in the molten liquid cylinder 2.

[0042] Ten liquid outlet holes 21 are arranged circumferentially on the cylinder wall of the molten liquid cylinder 2. A piston rod 3 is arranged in the molten liquid cylinder 2, and the material of the piston rod 3 is a high-temperature-resistant non-metallic material. Under the driving of an external force, the piston rod 3 slides up and down in the molten liquid cylinder 2, and at this time, the piston part of the piston rod 3 can block or open the liquid outlet holes 21.

[0043] Referring to Figure 3 , when the disc body 1 rotates during operation, the piston rod 3 moves upward, and the liquid outlet holes 21 are in an open state. Under the action of centrifugal force, the molten liquid in the molten liquid cylinder 2 flows to the cylinder wall, and the liquid level of the molten liquid at the cylinder wall part is higher than the height of the liquid outlet holes 21. In this way, part of the molten liquid can enter the liquid outlet holes 21.

[0044] Referring to Figure 4The piston rod 3 moves downward to block the liquid outlet hole 21, at this time the melt in the melt cylinder 2 cannot enter the liquid outlet hole 21, and the melt entering the liquid outlet hole 21 is thrown out to form a droplet. In this way, by adjusting the frequency of the upward and downward sliding of the piston rod 3, the amount and volume of the melt thrown out from the liquid outlet hole 21 can be controlled, and then a droplet with a diameter close to uniform can be obtained.

[0045] The size of the droplet is related to the rotation speed of the centrifugal disc, the hole diameter of the liquid outlet hole 21, the radius of the melt cylinder 2, the frequency of the upward and downward movement of the piston rod 3 and other parameters, among which the hole diameter of the liquid outlet hole 21 and the frequency of the upward and downward movement of the piston rod 3 play a crucial role in the generation of the droplet and the size of the generated droplet. Therefore, in order to obtain a droplet with a diameter in the range of 1-3mm, the hole diameter of the liquid outlet hole 21 and the frequency of the upward and downward movement of the piston rod 3 must be determined.

[0046] The hole diameter of the liquid outlet hole and the frequency of the upward and downward movement of the piston rod are derived as follows:

[0047] Let the radius of the liquid outlet hole be r, and the frequency of the upward and downward movement of the piston rod be f. The known conditions are: R is the radius of the melt cylinder, Sr is the spherical radius of the droplet, and ω is the rotation speed of the centrifugal disc.

[0048] Let the ratio of the radius of the liquid outlet hole to the spherical radius of the droplet be K, then:

[0049] r = K * Sr (1)

[0050] Reference Figure 5 The melt entering the liquid outlet hole is regarded as a cylinder, and the process of the melt entering the liquid outlet hole is regarded as a uniform accelerated linear motion with zero initial velocity, then:

[0051]

[0052] In formula (2), L is the length of the melt entering the liquid outlet hole during the opening of the liquid outlet hole.

[0053] Since the volume of the cylindrical melt is equal to that of the spherical droplet, then:

[0054]

[0055] Reference Figure 6 During the process of the droplet 7 being thrown out of the liquid outlet hole 21, surface tension F t is generated at the outlet of the liquid outlet hole 21.

[0056] F r = C * F t (4)

[0057] In formula (4), F rF = mω2R (6)

[0058] F = mω2R (6) t = 2πrσ (5)

[0059] In formula (5), σ is the surface tension coefficient of the metal melt.

[0060] It should be noted that if the radius of the liquid outlet hole is much larger than the spherical radius of the droplet, the mass of the droplet is large, and the centrifugal force F r experienced by the droplet is also much larger than the surface tension F t , and at this time the surface tension F t can even be ignored. However, if the liquid outlet hole is too large, two or more droplets will be formed in the process of the droplet being thrown out of the liquid outlet hole, which does not conform to the original design intention. Therefore, the radius of the liquid outlet hole can only be close to the spherical radius of the droplet.

[0061] Under the same conditions, the smaller the radius of the liquid outlet hole, the greater the influence of the surface tension on the droplet, and the more difficult the droplet is to be thrown out of the liquid outlet hole. Since the spherical radius of the droplet is only 0.5-1.5 mm, the influence of the surface tension on the droplet should be fully considered.

[0062] The centrifugal force F r experienced by the droplet is:

[0063] F = mω2R (6) r = mω 2 R = pπr 2 Lω 2 R (6)

[0064] In formula (6), m is the mass of the droplet, and p is the density of the metal melt. Since the wall of the melt cylinder is very thin, the total length of the liquid outlet hole can be ignored, and therefore the radius of the melt cylinder can be taken as the length from the droplet to the center of the circle.

[0065] By combining (1-6), we have:

[0066]

[0067]

[0068]

[0069] The above formula reveals the relationship between the radius of the liquid outlet hole, the up-and-down movement frequency of the piston rod, and the related parameters. Through the above formula, the radius of the liquid outlet hole and the up-and-down movement frequency of the piston rod can be inversely calculated according to the spherical radius of the droplet to be obtained, thereby providing a theoretical basis for controlling the size of the droplet.

[0070] For example, the ball radius Sr of the aluminum alloy melt drop to be obtained is 1 mm, the radius R of the melt cylinder is 10 mm, the rotating speed ω of the centrifugal disc is 20 revolutions per second, the density p of the aluminum alloy melt is 2.63 g / cm 3 , the surface tension coefficient σ of the aluminum alloy melt is 0.85 N / m, and C = 1.2 is taken. Then K is about 0.27, and the radius r of the liquid outlet hole is about 0.27 mm, and the frequency f of the up-and-down movement of the piston rod is about 33 times per second.

[0071] For another example, the ball radius Sr of the alloy steel melt drop to be obtained is 1 mm, the radius R of the melt cylinder is 10 mm, the rotating speed ω of the centrifugal disc is 10 revolutions per second, the density p of the alloy steel melt is 7.8 g / cm 3 , the surface tension coefficient σ of the alloy steel melt is 1.25 N / m, and C = 1.2 is taken. Then K is about 0.16, and the radius r of the liquid outlet hole is about 0.16 mm, and the frequency f of the up-and-down movement of the piston rod is about 14 times per second.

[0072] Embodiment 2

[0073] Referring to Figures 7-8 In this embodiment, a liquid injection pipe 4 is arranged in the piston rod 3, and a crucible is connected to the upper portion of the liquid injection pipe 4. The liquid injection pipe 4 is used to inject the metal melt into the melt cylinder 2, and to ensure that a certain amount of metal melt is always retained in the melt cylinder 2.

[0074] An external spline is arranged on the liquid injection pipe 4, and an internal spline is arranged on the upper portion of the piston rod 3. The piston rod 3 can slide up and down along the liquid injection pipe 4. The external spline and the internal spline are matched to prevent the piston rod 3 from rotating relative to the liquid injection pipe 4.

[0075] A transverse sliding slot is arranged on the upper portion of the piston rod 3, and an eccentric shaft 5 is matched and arranged in the transverse sliding slot. The eccentric shaft 5 is connected to a speed-regulating motor 6. When the speed-regulating motor 6 rotates, the piston rod 3 is driven to slide up and down through the matching of the eccentric shaft 5 and the sliding slot. The frequency of the up-and-down movement of the piston rod 3 depends on the rotating speed of the speed-regulating motor 6. The frequency of the up-and-down movement of the piston rod 3 can be adjusted by changing the rotating speed of the speed-regulating motor 6.

[0076] In addition to the above structure, there are many mechanisms capable of driving the piston rod 3 to make reciprocating linear movement, such as a crank slider mechanism, a cam slider mechanism, and a gas cylinder.

[0077] Embodiment 3

[0078] The radius of the liquid outlet hole 21 is very small, and it is easy to be blocked. Moreover, the hole diameter of the liquid outlet hole 21 needs to be changed according to the material of the melt.

[0079] Referring to Figure 9In order to facilitate replacement, a through hole is provided on the cylinder wall of the molten metal cylinder 2, and a liquid outlet nozzle 22 is detachably installed in the through hole. The inner hole in the liquid outlet nozzle 22 is the liquid outlet hole 21. In this way, the liquid outlet nozzle 22 can be quickly replaced, and the diameter of the liquid outlet hole 21 can also be quickly adjusted.

[0080] The portions not described in detail are prior art. Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A droplet generation mechanism for spray deposition forming, characterized by: The molten metal cylinder is arranged at the center of the centrifugal disc, the liquid outlet hole is arranged on the cylinder wall of the molten metal cylinder, and the piston rod is arranged in the molten metal cylinder; the piston rod is slidably arranged, and is used for blocking or opening the liquid outlet hole, so that the metal melt in the molten metal cylinder is intermittently and quantitatively thrown out from the liquid outlet hole to form the molten droplet; The radius of the liquid outlet hole is r, and the frequency of the up-down movement of the piston rod is f, and the following formula is obtained: In the formula, Sr is the spherical radius of the molten droplet, K is the ratio of the radius r of the liquid outlet hole to the spherical radius Sr of the molten droplet, R is the radius of the molten metal cylinder, p is the density of the metal melt, omega is the rotating speed of the centrifugal disc, sigma is the surface tension coefficient of the metal melt, and C is the coefficient of the molten droplet leaving the liquid outlet hole, and C is greater than or equal to 1.

2. A melt droplet generating mechanism for use in spray deposition forming as defined in claim 1, wherein: The injection pipe is arranged in the piston rod, and is used for injecting the metal melt into the molten metal cylinder.

3. A melt droplet generating mechanism for use in spray deposition forming as defined in claim 1, wherein: The molten droplet forming mechanism further comprises a crank slider mechanism, which is connected with the piston rod and is used for driving the piston rod to slide up and down.

4. A melt droplet generating mechanism for use in spray deposition forming as defined in claim 1, wherein The upper part of the piston rod is provided with a transverse sliding groove, an eccentric shaft is matched and installed in the transverse sliding groove, and the eccentric shaft is connected with the speed regulating motor; when the speed regulating motor rotates, the piston rod is driven to slide up and down through the cooperation of the eccentric shaft and the sliding groove.

5. A melt droplet generating mechanism for use in spray deposition forming as defined in claim 1, wherein: The through hole is arranged on the cylinder wall of the molten metal cylinder, and the liquid outlet nozzle is detachably installed in the through hole, and the channel in the liquid outlet nozzle is the liquid outlet hole.

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