suction mechanism

Abstract

The application discloses an adsorption mechanism, comprising a body, a cavity is arranged in the body, the cavity has a closed end and an open end, the open end is the end face of the adsorption mechanism for adsorbing a workpiece, a suction hole is arranged on the closed end, the suction hole deviates from the central axis of the cavity, the suction hole is communicated with a suction unit, a nozzle is arranged on the side wall surface of the cavity and is tangent to the side wall surface, external fluid flows into the cavity through the nozzle, and the suction unit sucks the fluid in the cavity through the suction hole. The adsorption mechanism can eliminate the stress concentration problem on the surface of the workpiece, effectively improve the adsorption effect and efficiency, and avoid cavitation phenomenon for liquid medium.

Description

Technical Field

[0001] This invention belongs to the field of fluid dynamics technology, and specifically relates to an adsorption mechanism. Background Technology

[0002] Vacuum suction cups are commonly used equipment on industrial production lines, typically for adsorbing and transporting workpieces. However, traditional silicone vacuum suction cups can only generate strong adsorption forces on smooth, hard surfaces. When the object being adsorbed has a rough surface (e.g., metal castings), an uneven surface (e.g., PCB circuit boards), or a soft texture (e.g., food), its adsorption force is greatly reduced or even impossible to establish. To adsorb and move these workpieces, CN112388660A discloses a suction cup utilizing rotating flow, such as... Figure 1a and Figure 1b As shown in the figure, this disclosed technology processes two tangential nozzles B on the circular wall of a cylindrical cavity A. When fluid is ejected from these two tangential nozzles B, it flows along the circular wall of cavity A, forming a rotating flow, as indicated by the arrows in the figure. However, the rotating flow generated in cavity A by supplying fluid solely through nozzles B is insufficient. Therefore, a suction unit C is needed to remove the high-speed rotating fluid from the suction port so that the rotating fluid on the outer periphery of cavity A reaches the central region of cavity A, maintaining a good rotating state in the central region of cavity A. The rotating flow can generate a centrifugal inertial effect. This centrifugal inertial effect causes the fluid to generate a negative pressure near the center of cavity A. This negative pressure can be used to adsorb the workpiece D located below the cavity, achieving the purpose of adsorbing and fixing the workpiece. However, CN112388660A has the following defects:

[0003] (1) Suction at the center of the cavity will create a very intense pressure distribution at the center, resulting in stress concentration on the workpiece at the position corresponding to the center of the cavity. Stress concentration can easily cause the stress on the workpiece to exceed its material strength limit, leading to destructive failure, such as fracture or plastic deformation.

[0004] (2) The suction force is obtained by integrating the product of negative pressure and the area of ​​action. The pressure distribution curve of this technology shows the characteristics of "protruding negative pressure center and low outer periphery". This indicates that the negative pressure increase obtained by suction only acts on a very small area in the center of the vortex cavity, while the negative pressure increase effect on the wider outer annular surface is not significant.

[0005] (3) The suction flow rate of the suction orifice depends on the pressure difference between the center of cavity A and the suction end of the suction unit. The way to increase the suction flow rate is to increase the pressure difference. However, the suction orifice is designed in the center of the cavity, which will result in a steep pressure distribution in the vortex cavity, forming a negative pressure peak with very low central pressure. This reduces the pressure difference between the two ends of the suction orifice, thereby reducing the suction flow rate.

[0006] (4) When the fluid medium in the adsorber is a liquid (e.g., water), the suction orifice draws in the center of cavity A, creating a very low negative pressure and resulting in cavitation. Therefore, the suction unit draws in cavitated gas while simultaneously drawing in water. In other words, the fluid drawn in by the suction unit can be a liquid, a gas, or a gas-liquid mixture. However, typical suction units can only draw in a single type of fluid. For example, a centrifugal pump can achieve a very high suction pressure differential when drawing in liquids, but once gas is drawn into the pump body, the suction pressure differential drops significantly. Another example is a diaphragm pump, which is quiet and low-power when drawing in gas, but produces significant vibration and noise once liquid is drawn in. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing an adsorption mechanism that can effectively improve adsorption effect and efficiency.

[0008] The technical solution adopted in this invention is as follows:

[0009] An adsorption mechanism includes a body with a cavity inside. The cavity has a closed end and an open end. The open end is the end face of the adsorption mechanism for adsorbing workpieces. A suction hole is provided on the closed end, and the suction hole is offset from the central axis of the cavity. The suction hole is connected to a suction unit. A nozzle tangent to the side wall of the cavity is provided. External fluid flows into the cavity through the nozzle, and the suction unit draws fluid from the cavity through the suction hole.

[0010] In the above technical solution, the distance between the suction hole and the central axis of the cavity is greater than 1 / 4 of the radius of the cavity.

[0011] Furthermore, the suction hole is an oblique hole so that when the fluid is drawn into the suction hole, the rotational velocity component and / or the radial velocity component of the fluid are maintained.

[0012] Furthermore, an opening is provided at the center of the closed end of the cavity, and a suction chamber is provided at the opening. The suction chamber is connected to the cavity, and the suction hole is provided on the side wall of the suction chamber, with the center line of the suction hole being tangent to the side wall of the suction chamber.

[0013] Furthermore, the suction hole is an annular slit formed on the closed end of the cavity.

[0014] The beneficial effects of this invention are:

[0015] Compared with the prior art, the adsorption mechanism of the present invention can eliminate the stress concentration problem on the surface of the workpiece and effectively improve the adsorption effect and efficiency, and avoid cavitation phenomenon for liquid media. Attached Figure Description

[0016] Figure 1a This is a front view of a cross-sectional section of a structure in the prior art (CN112388660A);

[0017] Figure 1b This is a top view of the structure in the prior art (CN112388660A);

[0018] Figure 2a This is a cross-sectional front view of the adsorption mechanism of Embodiment 1 of the present invention;

[0019] Figure 2b This is a top view of the adsorption mechanism of Embodiment 1 of the present invention;

[0020] Figure 3 This is a comparison of the measured pressure distribution results of the present invention and the structure of CN112388660A;

[0021] Figure 4 This is a top view of the adsorption mechanism of Embodiment 2 of the present invention (the suction hole adopts an oblique hole design);

[0022] Figure 5 This is a cross-sectional front view of the adsorption mechanism of Embodiment 3 of the present invention (the suction hole has a suction cavity);

[0023] Figure 6 This is a cross-sectional front view of the adsorption mechanism in Embodiment 4 of the present invention (the suction hole adopts an annular slit structure). Detailed Implementation

[0024] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example 1

[0026] Please refer to Figure 2a and Figure 2bAs shown, a first preferred embodiment of the adsorber of the present invention includes a body 1, within which a cavity 2 is provided. The internal space of the cavity 2 is cylindrical, having a closed upper bottom surface 4 (i.e., the closed end of the cavity), an open lower bottom surface 5 (i.e., the open end of the cavity), and a cylindrical curved surface 6 forming the sidewall of the cavity. A workpiece D is adsorbed on one side of the open lower bottom surface 5. When the suction flow rate is less than the supply flow rate of the nozzle, a gap 51 is formed between the body 1 and the workpiece surface, and a portion of the supply flow rate is discharged through the gap 51. A nozzle 7 is provided in the approximately tangential direction of the cylindrical curved surface 6, tangent to the sidewall of the cavity. External fluid flows into the cavity 2 at high speed through the nozzle 7 along the cylindrical curved surface 6 of the cavity 2, forming a rotating flow. Then, some or all of the fluid flows out from the gap between the adsorber and the workpiece. A plurality of suction holes 8 are provided on the upper bottom surface 4 of the cavity 2. Each suction hole is offset from the central axis of the cavity by a certain distance. The suction hole 8 is connected to the suction unit C via a connecting pipe 9. The suction unit extracts fluid from the cavity through the suction hole. Repeated experiments have shown that when the distance f from the suction hole 8 to the central axis of the cavity is greater than 1 / 4 of the radius of the cavity 2, the suction effect and the improvement in adsorption force are significantly better than when the suction hole is set in the center of the cavity.

[0027] Compared with CN112388660A, the advantages of this invention are:

[0028] (1) Figure 3 This is a comparison diagram of pressure distribution under the same suction power conditions. The present invention performs suction at a position off the central axis of the cavity, preventing drastic pressure changes and negative pressure peaks in the center of the cavity. This eliminates stress concentration problems on the workpiece surface.

[0029] (2) In the central part of the cavity, the pressure distribution of the present invention is relatively gentle, so the negative pressure at the upstream end of the suction orifice (i.e., one side of the cavity inside the suction orifice) is relatively weak, and the suction unit can draw a larger flow rate under the same power conditions. This allows more rotating fluid to move from the outer periphery of the cavity to the center of the cavity. Thus, a more complete rotating flow can be formed within the cavity. A more complete rotating flow can create a lower negative pressure within the cavity. Figure 3It can be seen that although the negative pressure at the center of the present invention is less than the pressure peak of the CN112388660A scheme, the negative pressure in other areas is greater than that in CN112388660A, and the area of ​​negative pressure in other areas is much larger than that of negative pressure peak. That is, the negative effect of weakening the negative pressure at the center is much less than the positive effect of increasing the negative pressure on the wider annular surface around it. Therefore, the overall adsorption force is greatly improved. (3) When the fluid medium is liquid (e.g., water), the negative pressure in the central area of ​​the present invention is relatively small, and serious cavitation will not occur or even the occurrence of cavitation can be avoided. This can alleviate the influence of gas-liquid mixing on the suction unit.

[0030] Example 2

[0031] In Embodiment 1, the suction orifice is an axial straight orifice. Before the fluid in the cavity is suctioned, the fluid has a circumferential rotational velocity component and a radial velocity component. When the fluid is suctioned into the suction orifice, while the axial velocity component is generated, the rotational and radial velocity components are decelerated to zero. This change in velocity components results in pressure loss and energy loss. To reduce pressure loss and energy loss, the suction orifice 8 in this embodiment adopts an oblique hole design, that is, the central axis of the suction orifice is not parallel to the central axis of the cavity. Figure 4 As shown, this is a second preferred embodiment of the adsorber of the present invention, wherein the suction orifice is machined by an oblique hole, and the flow direction inside the suction orifice can remain substantially the same as or partially the same as the flow direction inside the cavity. That is, when the fluid is drawn into the suction orifice, the fluid has an axial velocity component while retaining some of its original rotational velocity component and / or some of its radial velocity component, thereby reducing fluid pressure loss and energy consumption. Obviously,

[0032] Example 3

[0033] Figure 5 This is another design scheme of the present invention. Compared with Embodiment 1, the difference in this embodiment is that an opening is provided at the center of the closed end of the cavity, and a suction cavity 10 is provided at the opening. The suction cavity 10 has a circular wall surface, is closed at the top, and communicates with the cavity 2 at the bottom. The suction hole 8 is machined on the circular wall surface of the suction cavity 10, and the center line of the suction hole is tangent to the circular wall surface. When the fluid is drawn into the tangential suction hole, the original rotational velocity component and radial velocity component of the fluid can be maintained to a certain extent.

[0034] Example 4

[0035] Figure 4 The inclined suction hole presents certain difficulties in processing. This embodiment employs an annular slit structure design to simplify the process. For example... Figure 6As shown, this is a preferred embodiment of the present invention. Compared with Embodiment 1, the difference in this embodiment is that an annular slit structure 11 is provided at the center of the closed end of the cavity 2. This annular slit structure is equivalent to a suction hole. When the fluid is suctioned, the fluid flows in along the annular slit structure, and some of the rotational velocity component and radial velocity component of the fluid can be maintained.

[0036] In the above embodiments, there may be one suction hole or multiple suction holes.

[0037] The above description is only a part of the preferred embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adsorption mechanism, characterized in that, The device includes a main body, within which a cavity is provided. The cavity has a closed end and an open end. The open end is the end face of the adsorption mechanism for adsorbing the workpiece. The closed end of the cavity has an opening at its center, and a suction chamber is provided at the opening. The suction chamber has a circular wall surface, is closed at the top, and communicates with the cavity at the bottom. A suction hole is machined on the circular wall surface of the suction chamber, and the center line of the suction hole is tangent to the circular wall surface. A nozzle tangent to the side wall surface of the cavity is provided. External fluid flows into the cavity through the nozzle, and the suction unit draws fluid from the cavity through the suction hole.

2. An adsorption mechanism, characterized in that, The device includes a main body, within which a cavity is provided. The cavity has a closed end and an open end. The open end is the end face of the adsorption mechanism for adsorbing the workpiece. A suction hole is provided on the closed end, and the suction hole is offset from the central axis of the cavity. The suction hole communicates with a suction unit. A nozzle tangent to the side wall of the cavity is provided on the side wall. External fluid flows into the cavity through the nozzle, and the suction unit draws fluid from the cavity through the suction hole. The suction hole is an annular slit formed on the closed end of the cavity.

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