CN117302964A - Adsorption mechanism - Google Patents

Abstract

The invention discloses an adsorption mechanism, which comprises a body, wherein a cavity is arranged in the body, the cavity is provided with a closed end and an open end, the open end is an end face of an adsorption mechanism for adsorbing a workpiece, a suction hole is formed in the closed end and deviates from a central shaft of the cavity, the suction hole is communicated with a suction unit, a nozzle tangential to the side wall surface is arranged on the side wall surface of the cavity, 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 problem of stress concentration on the surface of a workpiece, can effectively improve the adsorption effect and efficiency, and can avoid cavitation for a liquid medium.

Description

Adsorption mechanism

Technical Field

The invention belongs to the technical field of fluid power, and particularly relates to an adsorption mechanism.

Background

Vacuum chucks are equipment commonly used in industrial production lines to chuck and transport workpieces. However, the conventional vacuum chuck of silica gel can generate strong adsorption force only on a smooth and hard plane, and when an object to be adsorbed has a rough surface (e.g., metal casting), a rugged surface (e.g., PCB circuit board), or a soft texture itself (e.g., food material), the adsorption force thereof is greatly impaired or even it is difficult to establish adsorption. To attract and move these workpieces, CN112388660a discloses a chuck utilizing a rotational flow, as shown in fig. 1a and 1 b. The disclosed technique machines two tangential nozzles B at the circular wall of the cylindrical cavity a. When the fluid is ejected from the two tangential nozzles B, the fluid flows along the circular wall of the chamber a, and a rotational flow is formed, as indicated by the arrow in the figure. However, the rotational flow generated in the chamber a by the operation of supplying the fluid only through the nozzle B is insufficient, and thus it is also necessary to suck the fluid rotating at a high speed from the suction hole by the suction unit C so that the rotational fluid at the outer periphery of the chamber a reaches the central region of the chamber a, thereby maintaining the fluid in a well-rotated state in the central region of the chamber a. The rotational flow may produce a centrifugal inertial effect. Centrifugal inertia causes the fluid to create a negative pressure near the center of the cavity a. The negative pressure can be used for adsorbing the workpiece D positioned below the cavity, so that the purposes of adsorbing and fixing the workpiece are realized. However, CN112388660a suffers from the following drawbacks:

(1) Suction in the center of the chamber creates a very intense pressure distribution in the center, creating stress concentrations on the workpiece at locations corresponding to the center of the chamber. Stress concentrations tend to cause the stress of a workpiece to exceed its material strength limit, resulting in destructive failure, such as fracture or plastic deformation.

(2) The suction force is obtained by integrating the product of the negative pressure and the acting area, and the pressure distribution technical curve of the technology shows the characteristics of protruding negative pressure center and low periphery, which indicates that the negative pressure lifting obtained by suction only acts on a small area of the center of the rotary cavity, and the lifting effect of the negative pressure on the circular ring surface with wider periphery is not great.

(3) The suction flow of the suction hole depends on the pressure difference between the pressure in the center of the cavity a and the suction end of the suction unit. The method of increasing the suction flow is to increase the pressure difference. However, the suction opening is designed in the center of the cavity, which results in a steep pressure distribution in the swirl chamber, creating a negative pressure spike with a very low center pressure, which reduces the pressure difference across the suction opening, resulting in a reduced suction flow.

(4) When the fluid medium in the adsorber is liquid (e.g., water), the suction hole sucks in the center of the cavity a, and a very low negative pressure is generated in the center of the cavity a, so that cavitation occurs. Therefore, the suction unit sucks the cavitation gas while sucking the water. That is, the suction fluid of the suction unit may be a liquid, a gas, or a gas-liquid mixed fluid. However, a typical pumping unit can only pump a single type of fluid. For example, centrifugal pumps can achieve high suction pressure differentials when pumping liquids, which can be greatly reduced once gas is pumped into the pump body. For example, a diaphragm pump has low noise and low power when sucking gas, and generates relatively intense vibration and noise once sucking liquid.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide an adsorption mechanism which can effectively improve the adsorption effect and efficiency.

The technical scheme adopted by the invention is as follows:

the utility model provides an adsorption equipment, includes the body be equipped with the cavity in the body, the cavity has a blind end and an open end, the open end is the terminal surface of adsorption equipment adsorption work piece be provided with the suction hole on the blind end, just the suction hole skew the center pin of cavity, suction hole and suction unit intercommunication be provided with on the lateral wall of cavity with the tangential nozzle of lateral wall, outside fluid passes through the nozzle inflow cavity, suction unit passes through the suction hole suction intracavity fluid.

In the above technical solution, further, the distance of the suction hole deviating from the central axis of the cavity is greater than 1/4 of the radius of the cavity.

Further, the suction holes are inclined holes such that a rotational velocity component of the fluid portion and/or a radial flow velocity component of the portion is maintained when the fluid is sucked into the suction holes.

Further, the center of the closed end of the cavity is provided with an opening, a suction cavity is arranged at the opening, the suction cavity is communicated with the cavity, the suction hole is arranged on the side wall surface of the suction cavity, and the center line of the suction hole is tangent with the side wall surface of the suction cavity.

Further, the suction hole is an annular gap formed in the closed end of the cavity.

The beneficial effects of the invention are as follows:

compared with the prior art, the adsorption mechanism can eliminate the problem of stress concentration on the surface of the workpiece, can effectively improve the adsorption effect and efficiency, and can avoid cavitation for liquid media.

Drawings

FIG. 1a is a cross-sectional elevation view of a prior art (CN 112388660A);

FIG. 1b is a top view of a prior art (CN 112388660A);

FIG. 2a is a cross-sectional elevation view of an adsorption mechanism according to embodiment 1 of the present invention;

FIG. 2b is a top view of the adsorption mechanism of embodiment 1 of the present invention;

FIG. 3 is a comparison of the measured results of the pressure distribution of the present invention and CN112388660A structure;

FIG. 4 is a top view of the adsorption mechanism of embodiment 2 of the present invention (the suction holes are designed as inclined holes);

FIG. 5 is a cross-sectional elevation view of the adsorbing mechanism of embodiment 3 of the present invention (suction holes with suction chambers);

fig. 6 is a cross-sectional elevation view of the adsorbing mechanism of embodiment 4 of the present invention (the suction hole adopts an annular slit structure).

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

Example 1

Referring to fig. 2a and 2b, a first preferred embodiment of the adsorber of the invention comprises a main body 1, wherein a cavity 2 is provided in the main body 1, and an inner space of the cavity 2 is in a cylindrical shape, and has a closed upper bottom surface 4 (i.e., a closed end of the cavity), an open lower bottom surface 5 (i.e., an open end of the cavity), and a cylindrical curved surface 6 forming a side wall surface of the cavity. The workpiece D is sucked to the side of the opening lower bottom surface 5. When the suction flow rate is smaller than the supply flow rate of the nozzle, a gap 51 is formed between the body 1 and the workpiece surface, and a part 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 so as to be tangential to the cavity sidewall surface, and the external fluid flows into the cavity 2 at a high speed along the cylindrical curved surface 6 of the cavity 2 through the nozzle 7, thereby forming a rotational flow. Then, part or all of the fluid flows out of the gap between the adsorber and the workpiece. A plurality of suction holes 8 are arranged on the upper bottom surface 4 of the cavity 2. Each suction hole is offset from the central axis of the cavity by a distance. The suction hole 8 communicates with the suction unit C through a communication pipe 9, and the suction unit withdraws the fluid in the cavity through the suction hole. Repeated experiments show that when the distance f of the suction hole 8 from the central axis of the cavity is more than 1/4 of the radius of the cavity 2, the suction effect and the lifting effect of the adsorption force are obviously better than those of the suction hole arranged in the center of the cavity.

Compared with CN112388660A, the invention has the advantages that:

(1) Fig. 3 is a graph comparing pressure distribution under the same suction power. The invention sucks in the position deviating from the central axis of the cavity, and the negative pressure in the center of the cavity can not form severe pressure change and negative pressure peak. This can eliminate the problem of stress concentration at the surface of the workpiece.

(2) In the central part of the cavity, the pressure distribution of the invention is relatively gentle, so that the negative pressure at the upstream end of the suction hole (i.e. at the inner side of the cavity of the suction hole) is relatively weak, and the suction unit can suck larger flow under the same power condition. This enables more rotating fluid to move from the outer periphery of the chamber to the central portion of the chamber. Thus, a more sufficient rotational flow can be formed within the cavity. A more adequate rotational flow can create a lower negative pressure within the chamber. As can be seen from fig. 3, although the negative pressure at the center is smaller than the pressure spike of the CN112388660a solution, the negative pressure in other areas is larger than the CN112388660a, and the negative pressure acting area in other areas is much larger than the acting area of the negative pressure spike. That is, the negative effect of weakening the negative pressure at the center is far smaller than the positive effect of negative pressure lifting on the annular surface with wider periphery, so that the whole adsorption force is greatly improved. (3) When the fluid medium is liquid (such as water), the negative pressure in the central area is smaller, so that serious cavitation can not be generated, and even the cavitation can be avoided, and the influence of the gas-liquid mixing phenomenon on the suction unit can be relieved.

Example 2

In embodiment 1, the suction holes are axial straight holes. Before the fluid in the chamber is pumped, the fluid has a rotational velocity component in the circumferential direction and a radial velocity component in the radial direction. As fluid is drawn into the suction aperture, the rotational and radial velocity components are decelerated to zero while the axial velocity component is generated. This change in velocity component produces pressure losses and energy losses. In order to reduce pressure losses and energy losses, the suction opening 8 of the present embodiment adopts an inclined opening design, i.e. the central axis of the suction opening is not parallel to the central axis of the cavity. As shown in fig. 4, a second preferred embodiment of the adsorber of the invention wherein the suction openings are beveled and the direction of flow in the suction openings and the direction of flow in the chamber can remain substantially or partially the same. That is, the fluid has an axial flow component while maintaining a partial rotational velocity component and/or a partial radial flow component of the fluid as it is drawn into the suction orifice, thereby reducing fluid pressure losses and energy losses. It is obvious that the process is not limited to,

example 3

Fig. 5 shows a further embodiment of the invention. Compared with embodiment 1, the difference of this embodiment is that an opening is provided in the center of the closed end of the cavity, a suction cavity 10 is provided at the opening, the suction cavity 10 has a circular wall surface, the top is closed, and the lower part is communicated with the cavity 2. The suction opening 8 is machined in the circular wall of the suction chamber 10, and the centre line of the suction opening is tangential to the circular wall. When fluid is sucked into the tangential suction holes, the rotational velocity component and the radial velocity component originally possessed by the fluid can be maintained to some extent.

Example 4

The inclined suction holes of fig. 4 have a certain difficulty in processing. The present embodiment adopts the design of the annular slit structure to simplify the processing. As shown in fig. 6, which is a preferred embodiment of the present invention, the present embodiment is different from embodiment 1 in that an annular slit structure 11 is provided at the center of the closed end of the chamber 2, which corresponds to the suction hole. As the fluid is pumped, the fluid flows in along the annular slit structure, and a part of the rotational velocity component as well as the radial velocity component of the fluid can be maintained.

In the above embodiments, the suction hole may be provided in one or more.

The above description is only of a few preferred embodiments of the present invention and is not intended to limit the present invention, but any modifications, equivalents, and improvements made within the spirit and principles of the present invention are intended to be included in the scope of the present invention.

Claims (4)

1. The suction mechanism is characterized by comprising a body, wherein a cavity is arranged in the body, the cavity is provided with a closed end and an open end, the open end is an end face of a workpiece to be sucked by the suction mechanism, a suction hole is formed in the closed end and deviates from a central axis of the cavity, the suction hole is communicated with a suction unit, a nozzle tangential to the side wall surface is formed in the side wall surface of the cavity, external fluid flows into the cavity through the nozzle, and the suction unit sucks the fluid in the cavity through the suction hole; the suction holes are inclined holes such that a rotational velocity component of the fluid portion and/or a radial flow velocity component of the portion is maintained as the fluid is sucked into the suction holes.

2. The adsorption mechanism of claim 1, wherein the suction aperture is offset from the central axis of the cavity by a distance greater than 1/4 of the radius of the cavity.

3. The adsorption mechanism of claim 1, wherein the cavity is open at the center of the closed end of the cavity, a suction cavity is arranged at the opening, the suction cavity is communicated with the cavity, the suction hole is arranged on the side wall surface of the suction cavity, and the center line of the suction hole is tangential to the side wall surface of the suction cavity.

4. The adsorption mechanism of claim 1, wherein the suction aperture is an annular slit open at the closed end of the cavity.