Conveying method based on self-adaptive upper pressing wheel

Abstract

The invention relates to a conveying method based on a self-adaptive upper pressing wheel, and relates to the field of solar cell silicon wafer production. According to the technical scheme, through the design of the upper pressing wheel of a gravity self-adaptive structure, the core defect of a traditional rigid roller is effectively overcome, the sleeve part is dynamically attached to the upper surface of the silicon wafer through self weight, the contact pressure can be automatically adjusted along with the thickness change of the silicon wafer and the operation fluctuation of equipment, and local stress concentration caused by rigid contact is avoided; especially in vulnerable areas such as silicon wafer edges and chamfers, uniform pressure distribution is realized through flexible contact, and the risk of microcrack induction is remarkably reduced. Meanwhile, due to the relative motion characteristic of the sleeve part and the axis part, mechanical impact caused by equipment vibration, roller parallelism deviation or chain fluctuation can be buffered, and external disturbance is converted into self-adaptive displacement of the sleeve part instead of being directly transmitted to the ultrathin silicon wafer. According to the passive self-adaptive mechanism without active pressure control, the process compatibility of the wet process equipment to the novel ultrathin silicon wafer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell silicon wafer production, and particularly to a conveying method based on an adaptive upper pressing wheel. Background Art

[0002] In the industrial production system of solar cell silicon wafers, horizontal roller chain wet process equipment, as the core process equipment, undertakes key wet chemical treatment processes such as silicon wafer surface cleaning, etching, and coating. This type of equipment realizes the stable conveying of silicon wafers in the horizontal direction through the transmission clamping structure formed by the upper pressing wheel and the lower roller, and its operating accuracy directly affects the yield rate of silicon wafers. In recent years, with the pursuit of battery conversion efficiency and cost control requirements in the photovoltaic industry, solar cell silicon wafers are developing rapidly towards ultra-thin. The mainstream silicon wafer thickness has gradually decreased from the early 180 - 200μm to below 150μm, and the thickness of silicon wafers for some new types of batteries such as HJT and TOPCon is even less than 100μm. However, the rigid upper pressing wheel structure commonly used in existing wet process equipment has gradually become difficult to adapt to the process challenges brought about by the ultra-thinning of silicon wafers. The material properties of rigid rollers (such as metals or hard engineering plastics) determine that they lack elastic buffering ability when contacting silicon wafers, resulting in uneven pressure distribution at the contact interface. When ultra-thin silicon wafers pass through the gap formed by the upper pressing wheel and the lower roller, the rigid contact of the rigid roller is likely to cause local stress concentration on the silicon wafer surface, especially in geometric stress-sensitive areas such as the edges and chamfers of the silicon wafer, which are extremely prone to inducing microcracks and expanding into fragments. In addition, inevitable mechanical vibrations, roller parallelism deviations, or minor fluctuations in the transmission chain during the operation of the equipment will be directly transmitted to the silicon wafer through the rigid roller, further exacerbating the stress load, seriously affecting production efficiency and increasing the material loss cost. This mismatch between the rigid transmission structure and the mechanical properties of ultra-thin silicon wafers has become the key technical bottleneck restricting the upgrade of wet process equipment. Summary of the Invention

[0003] The purpose of the present invention is to provide a conveying method based on an adaptive upper pressing wheel to solve the problems existing in the above-mentioned prior art.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A conveying method based on an adaptive upper pressing wheel, the method comprising: The solar cell silicon wafer is horizontally conveyed through the gap formed by the upper pressing wheel and the lower roller; In response to the conveying process of the solar cell silicon wafer, the lower surface of the solar cell silicon wafer contacts the lower roller and the lower roller provides a supporting force, and the upper surface of the solar cell silicon wafer contacts the upper pressing wheel and the upper pressing wheel adaptively presses the solar cell silicon wafer; Among them, the upper pressing wheel includes an axis part and a sleeve part located outside the axis part, and the sleeve part is dynamically and tightly attached to the upper surface of the silicon wafer of the solar cell by its own weight adaptively.

[0005] In a possible implementation manner, the axis part includes an axis, and the sleeve part includes an axis ring sleeved on the outer periphery of the axis and an outer sleeve located outside the axis ring, and the outer sleeve is elastically connected to the axis ring through an elastic member; The outer sleeve is of a single-layer or multi-layer structure; The outer sleeve is a whole piece or composed of multiple pieces arranged at axial intervals.

[0006] In a possible implementation manner, the outer sleeve is elastically connected to the axis ring through a plurality of cylindrically coiled compression springs distributed radially, and the material of the cylindrically coiled compression springs is stainless steel and the surface is nickel-plated.

[0007] In a possible implementation manner, the outer sleeve is elastically connected to the axis ring through a plurality of wave-shaped spring washers distributed radially.

[0008] In a possible implementation manner, the outer sleeve is elastically connected to the axis ring through a plurality of micro conical disc springs distributed radially.

[0009] In a possible implementation manner, the outer sleeve is elastically connected to the axis ring through a plurality of elastic rubber columns distributed radially.

[0010] In a possible implementation manner, the outer sleeve is elastically connected to the axis ring through a plurality of elastic sheets distributed radially, and the elastic sheets are stainless steel elastic sheets or polymer compound elastic sheets.

[0011] In a possible implementation manner, the outer sleeve is elastically connected to the axis ring through a plurality of elastic sponges distributed radially.

[0012] In a possible implementation manner, the outer sleeve is elastically connected to the axis ring through a cylindrically coiled compression spring arranged axially.

[0013] In a possible implementation manner, the upper pressing wheel and the lower roller rotate synchronously, and the linear velocity difference between the two does not exceed ±0.1 m / min.

[0014] The beneficial effects brought by the technical solution provided by the present invention at least include: Through the design of the upper pressing wheel with a gravity self - adapting structure, this technical solution effectively solves the core defects of traditional rigid rollers. The casing part dynamically adheres to the upper surface of the silicon wafer by its own weight, and can automatically adjust the contact pressure according to the change of the silicon wafer thickness and the operation fluctuation of the equipment, avoiding local stress concentration caused by rigid contact. Especially in vulnerable areas such as the edge and chamfer of the silicon wafer, uniform pressure distribution is achieved through flexible contact, significantly reducing the risk of induced micro - cracks. At the same time, the relative motion characteristics between the casing part and the central axis part can buffer mechanical shocks caused by equipment vibration, roller parallelism deviation or chain fluctuation, converting external disturbances into self - adapting displacements of the casing part instead of directly transmitting them to the ultra - thin silicon wafer. This passive self - adapting mechanism without active pressure control perfectly matches the low flexural strength characteristics after the silicon wafer is thinned, improving the process compatibility of wet - process equipment with new ultra - thin silicon wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention.

[0016] Figure 1 The flowchart of the conveying method based on the self - adapting upper pressing wheel provided by an exemplary embodiment of the present invention is shown.

[0017] Figure 2 The schematic structural diagram of the conveying process of the conveying method based on the self - adapting upper pressing wheel provided by an exemplary embodiment of the present invention is shown.

[0018] Figure 3 The schematic radial cross - sectional view of an upper pressing wheel provided by an exemplary embodiment of the present invention is shown.

[0019] Figure 4 The schematic axial cross - sectional view of an upper pressing wheel provided by an exemplary embodiment of the present invention is shown.

[0020] Figure 5 The schematic structural diagram of an upper pressing wheel provided by an exemplary embodiment of the present invention is shown; wherein, Figure 5 (a) is an axonometric view, Figure 5 (b) is a radial cross - sectional view.

[0021] Figure 6 The schematic structural diagram of another upper pressing wheel provided by an exemplary embodiment of the present invention is shown; wherein, Figure 6 (a) is an axonometric view, Figure 6 (b) is a radial cross - sectional view.

[0022] Figure 7 The schematic structural diagram of another upper pressing wheel provided by an exemplary embodiment of the present invention is shown.

[0023] Figure 8 The axial sectional view of another upper pressing wheel provided by an exemplary embodiment of the present invention is shown.

[0024] In the figure: 1, silicon wafer of solar cell; 2, upper pressing wheel; 21, axis center; 22, axis center ring; 23, outer sleeve; 231, rigid outer sleeve; 232, flexible outer sleeve; 24, elastic member; 3, lower roller. Detailed implementation manners

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Among them, the same components are denoted by the same reference numerals. It should be noted that the terms "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the accompanying drawings of the present invention specification, and the terms "bottom surface" and "top surface", "inner" and "outer" refer to facing or away from a specific component respectively. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention specification, "a plurality of" means two or more.

[0027] The present invention will be further described in conjunction with the accompanying drawings and embodiments.

[0028] Embodiment 1 Figure 1 The flowchart of a conveying method based on an adaptive upper pressing wheel provided by an exemplary embodiment of the present invention is shown. Figure 2 The structural schematic diagram of the conveying process of a conveying method based on an adaptive upper pressing wheel provided by an exemplary embodiment of the present invention is shown. The conveying method based on the adaptive upper pressing wheel includes: Step 101, the silicon wafer 1 of the solar cell is horizontally conveyed through the gap formed by the upper pressing wheel 2 and the lower roller 3.

[0029] It is worth mentioning that the upper pressing wheel and the lower roller rotate synchronously, and the linear velocity difference between the two does not exceed ±0.1 m / min. In order to achieve such precise synchronous rotation, a servo motor can be used in cooperation with an absolute encoder, and the synchronous control of the upper pressing wheel and the lower roller can be realized through the CAN bus.

[0030] Step 102: In response to the conveyance of the solar cell silicon wafer 1, when the lower surface of the solar cell silicon wafer 1 contacts the lower roller 3 and the lower roller 3 provides a supporting force, the upper surface of the solar cell silicon wafer 1 contacts the upper pressing wheel 2, and the upper pressing wheel 2 adaptively presses the solar cell silicon wafer 1; wherein, the upper pressing wheel 2 includes an axial center part and a sleeve part located outside the axial center part, and the sleeve part adaptively and dynamically fits tightly with the upper surface of the solar cell silicon wafer 1 by its own weight.

[0031] It can be understood that the self-weight design of the sleeve part in the upper pressing wheel needs to be accurately calculated according to the size, thickness of the solar cell silicon wafer and process requirements, so as to ensure that sufficient pressure can be provided without causing excessive pressure on the solar cell silicon wafer and resulting in damage, realizing that the upper pressing wheel can adaptively adjust according to the minute undulations on the surface of the solar cell silicon wafer during the fitting process, and ensuring the contact uniformity of the entire upper surface.

[0032] Furthermore, Figure 3 Fig. shows a schematic radial cross-section of an upper pressing wheel provided by an exemplary embodiment of the present invention. Figure 4 Fig. shows a schematic axial cross-section of an upper pressing wheel provided by an exemplary embodiment of the present invention. The axial center part includes an axial center 21, the sleeve part includes an axial center ring 22 sleeved on the outer periphery of the axial center 21, and an outer sleeve 23 located outside the axial center ring 22. The outer sleeve 23 is elastically connected to the axial center ring 22 through an elastic member 24. The outer sleeve 23 is composed of a single-layer outer sleeve, and the single-layer outer sleeve can be a rigid material, such as a stainless steel sleeve; or a non-rigid material, such as a rubber tube.

[0033] In one example, Figure 5 Fig. shows a schematic structural diagram of an upper pressing wheel provided by an exemplary embodiment of the present invention; wherein, Figure 5 (a) is an axonometric view, Figure 5 (b) is a radial cross-sectional view. In this example, the elastic member 24 is an elastic sheet, and the elastic sheet is a stainless steel elastic sheet or a polymer compound elastic sheet.

[0034] In another example, the axial center ring 22 and the outer sleeve 23 are elastically connected through a plurality of cylindrically helical compression springs evenly distributed in the radial direction. The cylindrically helical compression springs are made of stainless steel and the surface is nickel-plated. The stainless steel material has good corrosion resistance and strength, and the nickel-plating treatment further improves the corrosion resistance and wear resistance of the spring. Parameters such as the wire diameter, number of turns, and elastic coefficient of the cylindrically helical compression springs need to be calculated and selected according to the actual working conditions to ensure that they can provide appropriate elastic force. For example, the wire diameter is generally between 0.5 - 1.2 mm, the effective number of turns is 5 - 8 turns, and the elastic coefficient is between 0.8 - 1.5 N / mm.

[0035] In another example, the central axis ring 22 and the outer sleeve 23 are elastically connected by a plurality of radially evenly distributed wavy spring washers. The wavy spring washers have unique elastic characteristics and can provide large elastic deformation in a small space. Parameters such as the waveform height and the wave crest spacing affect their elastic performance. The waveform height is generally between 0.3 and 0.8 millimeters, and the wave crest spacing is between 1.2 and 2.0 millimeters.

[0036] In another example, the central axis ring 22 and the outer sleeve 23 are elastically connected by a plurality of radially evenly distributed micro conical disc springs. The micro conical disc springs have high load-bearing capacity and good elastic stability. Parameters such as their outer diameter, cone angle, and combination method need to be optimized according to actual requirements. The outer diameter is generally between 6 and 10 millimeters, the cone angle is between 18° and 25°, and the combination method can be 3 to 5 pieces in butt joint and superposition.

[0037] In another example, the central axis ring 22 and the outer sleeve 23 are elastically connected by a plurality of radially evenly distributed elastic rubber columns. The Shore hardness of the elastic rubber columns needs to be selected according to the thickness and characteristics of the silicon wafers of the solar cells; for relatively thin solar cell silicon wafers, soft rubber columns with a Shore hardness between 50 and 60 HA can be selected; for relatively thick solar cell silicon wafers, hard rubber columns with a Shore hardness between 70 and 80 HA can be selected. At the same time, the dynamic compression set of the elastic rubber columns should be less than 10% to ensure their long-term use stability.

[0038] In another example, the central axis ring 22 and the outer sleeve 23 are elastically connected by a plurality of radially evenly distributed elastic sponges. The elastic sponges are usually made of polyurethane or silicon-based materials with excellent aging resistance and insulation properties. Their porous structure can provide buffering and shock absorption performance, effectively reducing the impact of mechanical vibration.

[0039] In the embodiment of the present application, a servo motor is selected to drive the central axis, which can accurately control the rotation speed of the central axis and can be flexibly adjusted according to different stages of the process.

[0040] In the embodiment of the present application, the gravity of the upper pressing wheel pressing on the solar cell silicon wafer is determined by the number of elastic members, the specifications of the elastic members, the wall thickness of the outer sleeve, and the material of the outer sleeve.

[0041] Optionally, the cross-sectional shape of the central axis 41 includes but is not limited to one of a circle, an ellipse, a triangle, a quadrilateral, a pentagon, a hexagon, and an octagon.

[0042] Optionally, the central axis 41 can be composed of a single material or more than one material. For example, an insulating material can be coated on the central axis 41.

[0043] Optionally, the cross-sectional shape of the central axis ring 22 includes, but is not limited to, one of a circle, an ellipse, a triangle, a quadrilateral, a pentagon, a hexagon, and an octagon.

[0044] Embodiment 2 This embodiment is basically the same as Embodiment 1, except that: Figure 6 Fig. shows a schematic structural diagram of another upper pressing wheel provided by an exemplary embodiment of the present invention; wherein, Figure 6 (a) is an axonometric view, Figure 6 (b) is a radial cross-sectional view. In this embodiment, the outer sleeve 23 is composed of a layer of rigid outer sleeve 231 and a layer of flexible outer sleeve 232. According to specific application requirements, the outer sleeve 23 can be composed of more than two outer sleeves.

[0045] Embodiment 3 This embodiment is basically the same as Embodiment 1, except that: Figure 7 Fig. shows a schematic structural diagram of another upper pressing wheel provided by an exemplary embodiment of the present invention. In this embodiment, the elastic member 24 is an axially arranged cylindrical helical compression spring, which connects the outer sleeve 23 and the central axis ring 22, and the spring is a stainless steel spring or a polymer compound spring.

[0046] Embodiment 4 This embodiment is basically the same as Embodiment 1, except that: Figure 8 Fig. shows an axial cross-sectional schematic diagram of another upper pressing wheel provided by an exemplary embodiment of the present invention. In this embodiment, the upper pressing wheel 2 is realized with a central axis part corresponding to multiple sleeve parts. A plurality of spaced-apart outer sleeves 23 are arranged on the outer periphery of the central axis 21. At both inner ends of each outer sleeve 23, a central axis ring 22 is connected through an elastic member 24, and the central axis ring 22 is sleeved on the central axis 21.

[0047] In summary, through the design of the upper pressing wheel with a gravity self-adaptive structure, the present technical solution effectively solves the core defects of traditional rigid rollers. The sleeve part dynamically fits the upper surface of the silicon wafer by its own weight, and can automatically adjust the contact pressure with the change of the silicon wafer thickness and the operation fluctuation of the equipment, avoiding local stress concentration caused by rigid contact; especially in vulnerable areas such as the edge and chamfer of the silicon wafer, uniform pressure distribution is achieved through flexible contact, significantly reducing the risk of inducing microcracks. At the same time, the relative movement characteristics of the sleeve part and the central axis part can buffer the mechanical impact caused by equipment vibration, roller parallelism deviation or chain fluctuation, converting external disturbances into adaptive displacement of the sleeve part, rather than directly transmitting to the ultra-thin silicon wafer. This passive self-adaptive mechanism without active pressure control perfectly matches the low bending strength characteristics of the ultra-thin silicon wafer after thinning, improving the process compatibility of wet process equipment with new ultra-thin silicon wafers.

[0048] In the embodiments disclosed by the present invention, terms such as "installation", "connection", "linkage", "fixation" shall be understood in a broad sense. For example, "connection" may be a fixed connection, a detachable connection, or an integral connection; "linkage" may be a direct linkage or an indirect linkage through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments disclosed by the present invention may be understood according to specific circumstances.

[0049] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A conveying method based on an adaptive upper pressure wheel, characterized in that: The method comprises: The solar cell silicon wafers are transported horizontally through the gap formed by the upper pressing wheel and the lower roller; In response to the conveying process of the solar cell silicon wafer, the lower surface of the solar cell silicon wafer contacts the lower roller and is supported by the lower roller, and the upper surface of the solar cell silicon wafer contacts the upper pressing wheel and is adaptively pressed by the upper pressing wheel to hold the solar cell silicon wafer; The upper pressure wheel comprises an axial portion and a sleeve portion located outside the axial portion, and the sleeve portion dynamically and tightly fits with the upper surface of the solar cell silicon wafer in an adaptive manner relying on its own weight.

2. The method for conveying based on the adaptive upper pressing wheel according to claim 1 is characterized in that: The axial part includes an axial center, and the sleeve part includes an axial ring sleeved on the outer periphery of the axial center, and an outer sleeve located outside the axial ring, and the outer sleeve is elastically connected to the axial ring through an elastic member; The outer sleeve is a single-layer or multi-layer structure; The outer sleeve is a whole piece, or is composed of a plurality of pieces arranged at intervals in the axial direction.

3. The method for conveying based on the adaptive upper pressing wheel according to claim 2 is characterized in that: The outer sleeve is elastically connected to the shaft ring through a plurality of radially distributed cylindrical helical compression springs. The cylindrical helical compression springs are made of stainless steel and have a nickel-plated surface.

4. The method for conveying based on the adaptive upper pressing wheel according to claim 2 is characterized in that: The outer sleeve is elastically connected to the shaft ring via a plurality of radially distributed wave-shaped spring washers.

5. The method for conveying based on the adaptive upper pressing wheel according to claim 2 is characterized in that: The outer sleeve is elastically connected to the shaft ring via a plurality of radially distributed micro conical disc springs.

6. The method for conveying based on the adaptive upper pressing wheel according to claim 2 is characterized in that: The outer sleeve is elastically connected to the shaft ring via a plurality of radially distributed elastic rubber columns.

7. The method for conveying based on the adaptive upper pressing wheel according to claim 2 is characterized in that: The outer sleeve is elastically connected to the shaft ring through a plurality of radially distributed elastic sheets, and the elastic sheets are stainless steel elastic sheets or polymer compound elastic sheets.

8. The method for conveying based on the adaptive upper pressing wheel according to claim 2 is characterized in that: The outer sleeve is elastically connected to the shaft ring via a plurality of radially distributed elastic sponges.

9. The method for conveying based on the adaptive upper pressing wheel according to claim 2, characterized in that: The outer sleeve is elastically connected to the shaft ring via an axially arranged cylindrical helical compression spring.

10. The method for conveying based on an adaptive upper pressing wheel according to any one of claims 1 to 9, characterized in that: The upper pressing wheel rotates synchronously with the lower roller, and the linear speed difference between the two does not exceed ±0.1m / min.

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