1. A preparation method of a PCB (printed Circuit Board) conveying flat belt of an SMT (surface mount technology) production line is characterized by comprising the following production processes:

step S1: preparing materials for preliminary treatment, wherein the preparing materials comprise preparing polyester non-woven fabric with a plain velvet surface and a nylon sheet base at the same time, and performing sanding and slitting treatment on the polyester non-woven fabric with the plain velvet surface and performing flexibility treatment on the nylon sheet base;

step S2: the system is glued, and the system is glued including electrically conductive PU coating glue preparation and nylon resin glue preparation, wherein:

when the conductive PU coating adhesive is prepared, firstly adding methanol into a reaction pot according to a certain proportion, starting stirring, slowly adding PU resin, nano conductive carbon black powder and the like, keeping the temperature of the reaction pot at 60-62 ℃, continuously reacting for 6-8 hours, and then filtering and discharging by using a filter screen;

when the nylon resin adhesive is prepared, firstly adding ethanol into a reaction kettle, starting stirring, slowly adding nylon particles, heating to 60-70 ℃ to dissolve the nylon particles, then slowly adding solvents such as formaldehyde, continuously reacting for 2 hours at 60-70 ℃, cooling, placing into an aluminum barrel, washing with cold water, separating precipitates, then pouring the precipitates into an aluminum tray for airing, and preparing the precipitates into a solution with a certain concentration for later use to form a semi-finished solution; dissolving resin in an ethanol solution according to a certain concentration, controlling the temperature to be 50-60 ℃, mixing the semi-finished product solution and the resin solution together according to a certain proportion at 40-50 ℃, uniformly stirring, slightly cooling, adding an accelerant, and uniformly stirring;

step S3: and gluing, wherein the gluing comprises coating a conductive PU coating on the composite surface of the polyester non-woven fabric with a velveteen surface and coating nylon resin adhesive on the two surfaces of a nylon sheet base, and the coating comprises the following steps:

when the polyester non-woven fabric composite surface of the plain velvet surface is coated, the temperature of an oven is controlled to be 160-180 ℃, the polyester non-woven fabric composite surface of the plain velvet surface is uniformly coated with glue, and the frosted surface is kept clean;

when the nylon sheet base is coated, performing special flexibility treatment, cleaning with butanone and drying, controlling the temperature of an oven at 90-110 ℃, and uniformly coating the double surfaces of the nylon sheet base;

step S4: compounding, namely after the nylon sheet is taken out of an oven, covering polyester non-woven fabrics with plain velvet surfaces on two sides of the nylon sheet base, aligning the upper layer and the lower layer, covering the nylon sheet base by the polyester non-woven fabrics with the plain velvet surfaces, keeping the belt body in a tensioned state during continuous compounding, cleaning and flattening the surface, fully cooling the belt body when the last car is vulcanized or the car is shut down midway, and releasing pressure and releasing;

step S5: cutting, namely trimming a reference edge of the belt body by taking one edge of the nylon sheet as a reference, cutting according to the size by taking the reference edge as a positive edge, and grinding the joint;

step S6: gluing, cleaning the joints, respectively coating corresponding glue on the polyester non-woven fabric and the nylon sheet base on the velveteen surface, drying, and performing involution and cold pressing; when the joint is hot pressed, two layers of canvas and one layer of polypropylene fabric are respectively padded up and down;

step S7: grinding the belt, and cleaning and finishing the joints after the belt is taken off the machine;

step S8: and (5) inspecting and warehousing, spraying and printing corresponding information on the belt body, and packaging and warehousing after inspection.

2. The method for preparing the PCB conveying flat belt for the SMT production line according to claim 1, wherein the method comprises the following steps: in step S3, when the polyester non-woven fabric composite surface with the velveteen surface is coated, the polyester non-woven fabric composite surface should be covered with a plastic film and rolled up after being taken out of the oven.

3. The method for preparing the PCB conveying flat belt for the SMT production line according to claim 1, wherein the method comprises the following steps: in step S5, cutting width error is-0.2 mm, length is measured and a joint line is drawn at an angle of 60 degrees according to the thickness and the width of the belt; the grinding joints are laid flat, the inclined plane keeps flat and uniform in thickness, when the two joints are closed, the polyester non-woven fabric with the flat velvet surface is matched with the polyester non-woven fabric with the flat velvet surface, the nylon sheet base is matched with the nylon sheet base, the thickness of the joints is not lower than that of the belt body, and the error is +0.1 mm.

4. The method for preparing the PCB conveying flat belt for the SMT production line according to claim 1, wherein the method comprises the following steps: in step S6, when the joints are aligned, the respective portions are aligned, and the joints do not overlap or collapse and the straightness is ensured.

5. The method for preparing the PCB conveying flat belt for the SMT production line according to claim 1, wherein the method comprises the following steps: in step S8, the information on the jet printing includes the specification, the date of manufacture, and the direction of operation.

Background

The prior flat conveying belt mainly comprises a polyamide sheet-based transmission flat belt or a light conveying flat belt, and a flat conveying belt combining the functions of the flat belts into a whole is not available at present. At present, a polyamide sheet base flat belt mainly used for transmission is mostly selected on an SMT production line for transmission, and the following defects are mainly existed:

(1) the polyamide sheet base flat belt takes power transmission as a main part, a transmission mechanism is required to be matched with a belt wheel with a larger diameter (large turning radius) or at least the diameter of the belt wheel is required to meet the thickness selection of the flat belt, but an SMT production line belongs to high-precision high-speed compact equipment, the diameters of the belt wheels selected by design at home and abroad are smaller, and the minimum diameter is 8mm, so that the general polyamide sheet base flat belt is easy to bend, fatigue and burst in practical application, large in transmission jumping, affects the production efficiency, and can only temporarily substitute but is not durable; the light-weight PVC or PU conveying flat belt mainly adopts light-load conveying, but is not good when applied to an SMT production line because the belt is easy to elongate and skid due to high-speed bearing; whether a polyamide base flat belt or a light conveying flat belt, the wear resistance of the flat belt can be reduced on the surface friction material as long as the antistatic performance is improved.

(2) In the production and conveying process of the PCB of the SMT equipment, the poor products of the precision circuit board are increased due to the fact that scratches are generated by friction in the production and conveying process of the precision circuit board because the rubber of the surface conveying layer of the polyamide base flat belt is easy to age and harden, and production quality and benefits are affected.

(3) The flat belt of the polyamide sheet base on the SMT equipment is in rigid contact friction with the aluminum profile of the rack and a metal (clamp), the phenomena of surface rubber layer friction powder falling and inner interlayer cloth edge friction hair falling can occur in use, circuit boards and electronic components are easily polluted, static accumulation is generated, and dangers such as PCB board puncture and the like occur.

(4) The polyamide sheet base flat belt takes a polyamide sheet base as a framework tensile body, the surface layer material is mainly made of synthetic rubber, the produced rubber mixing is either open mixing or banburying, dust has large pollution to the environment, chemical auxiliary materials are not good for the health of production workers, and the product has no environmental protection and recyclable value.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a method for preparing a PCB (printed circuit board) conveying flat belt of an SMT (surface mount technology) production line, which can effectively solve the problems in the background art.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a method for preparing a PCB (printed Circuit Board) conveying flat belt of an SMT (surface mount technology) production line comprises the following production processes:

step S1: and (5) primary treatment of the prepared materials. The material preparation comprises the steps of preparing the polyester non-woven fabric with the plain velvet surface and the nylon sheet base at the same time, carrying out sanding and splitting treatment on the polyester non-woven fabric with the plain velvet surface, and carrying out flexibility treatment on the nylon sheet base.

Step S2: and (5) preparing glue. The system is glued including electrically conductive PU coating glue preparation and nylon resin glue preparation, wherein:

when the conductive PU coating adhesive is prepared, firstly adding methanol into a reaction pot according to a certain proportion, starting stirring, slowly adding PU resin, nano conductive carbon black powder and the like, keeping the temperature of the reaction pot at 60-62 ℃, continuously reacting for 6-8 hours, and then filtering and discharging by using a filter screen;

when the nylon resin adhesive is prepared, firstly adding ethanol into a reaction kettle, starting stirring, slowly adding nylon particles, heating to 60-70 ℃ to dissolve the nylon particles, then slowly adding solvents such as formaldehyde, continuously reacting for 2 hours at 60-70 ℃, cooling, placing into an aluminum barrel, washing with cold water, separating precipitates, then pouring the precipitates into an aluminum tray for airing, and preparing the precipitates into a solution with a certain concentration for later use to form a semi-finished solution; dissolving resin in an ethanol solution according to a certain concentration, controlling the temperature at 50-60 ℃, mixing the semi-finished product solution and the resin solution together according to a certain proportion at 40-50 ℃, uniformly stirring, slightly cooling, adding an accelerant, and uniformly stirring.

Step S3: and (6) gluing. The coating comprises coating a conductive PU coating adhesive on the polyester non-woven fabric composite surface of the velveteen surface and coating a nylon resin adhesive on the two surfaces of a nylon sheet base, wherein:

when the polyester non-woven fabric composite surface of the plain velvet surface is coated, the temperature of an oven is controlled to be 160-180 ℃, the coating of the polyester non-woven fabric composite surface of the plain velvet surface is uniform, and the frosted surface is kept clean;

when the nylon sheet base is coated, the special flexibility treatment is firstly carried out, then the cleaning and the drying are carried out by butanone, the temperature of an oven is controlled to be 90-110 ℃, and the double surfaces of the nylon sheet base are uniformly coated with glue.

Step S4: and (4) compounding. And after the nylon base sheet is taken out of the oven, the two sides of the nylon base sheet are both covered with polyester non-woven fabrics with plain velvet surfaces, the upper layer and the lower layer are aligned, and the polyester non-woven fabrics with plain velvet surfaces cover the nylon base sheet. When the continuity is compounded, the belt body needs to be kept in a tensioning state, the surface is clean and flat, and the belt body needs to be fully cooled when the last vehicle is vulcanized or the machine is stopped midway, and the pressure is released.

Step S5: and (5) cutting. And (3) trimming the reference edge of the belt body by taking one side of the nylon sheet as the reference, cutting according to the size by taking the reference edge as the positive side, and grinding the joint.

Step S6: and (6) gluing. After cleaning the joints, respectively coating corresponding glue on the polyester non-woven fabric and the nylon sheet base with the velveteen surface, drying, and performing involution and cold pressing; when the joint is hot pressed, two layers of canvas and one layer of polypropylene fabric are respectively padded up and down.

Step S7: and (7) grinding the belt. And after the connector is unloaded, cleaning and arranging the connector.

Step S8: and (7) checking and warehousing. And (5) spraying and printing corresponding information on the belt body, and packaging and warehousing after inspection.

Further, in step S3, when the polyester non-woven fabric composite surface with a velvety surface is coated, the polyester non-woven fabric composite surface should be covered with a plastic film and rolled up after being taken out of the oven.

Further, in step S5, the cutting width error is-0.2 mm, the length is measured and the joint line is drawn at an angle of 60 degrees according to the thickness and width of the tape; the grinding joints are placed flat, the inclined plane keeps flat and uniform in thickness, when the two joints are closed, the polyester non-woven fabric with the flat velvet surface is matched with the polyester non-woven fabric with the flat velvet surface, the nylon sheet base is matched with the nylon sheet base, the thickness of the joints is not lower than that of the belt body, and the error is +0.1 mm.

Further, in step S6, when the joints are aligned, the respective portions are aligned, the joints do not overlap or collapse, and the straightness is ensured.

Further, in step S8, the information of the jet printing includes the specification, the date of manufacture, and the direction of operation.

Compared with the prior art, the invention has the beneficial effects that:

(1) the polyurethane non-woven fabric has good surface plush effect, moderate hardness and soft hand feeling, the friction coefficient can be controlled within the range of 0.1-0.2, and the friction force is very suitable for conveying SMT circuit boards and electronic components, so that PCB boards and electronic components with high precision requirements can not be scratched.

(2) The polyurethane non-woven fabric is made of environment-friendly fibers, has the advantages of no fluffing, no deformation and permanent antistatic property in use, has higher tearing strength than a rubber surface, and can meet the functional requirements of conveying circuit boards and electronic components.

(3) The high-density polyester non-woven fabric has better air permeability and wear resistance, which is 3-5 times of that of synthetic rubber.

(4) The bending resistance is excellent and is 5-7 times of that of natural rubber.

(5) Has excellent heat resistance, oil resistance and aging resistance, and can deal with various severe use environments.

(6) The tensile skeleton adopts a specially processed nylon sheet base PA66, so that the flexibility is greatly improved, the 1% stress at definite elongation can be improved by 30-100%, the elongation at break can be reduced by 20-30%, and the tensile skeleton is suitable for a conveying mechanism with a smaller diameter belt wheel.

Drawings

FIG. 1 is an overall process flow diagram of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in FIG. 1, the invention provides a method for preparing a PCB (printed Circuit Board) conveying flat belt for an SMT production line, which comprises the following steps:

step S1: and (5) primary treatment of the prepared materials. The material preparation comprises the steps of preparing the polyester non-woven fabric with the plain velvet surface and the nylon sheet base at the same time, carrying out sanding and splitting treatment on the polyester non-woven fabric with the plain velvet surface, and carrying out flexibility treatment on the nylon sheet base.

Step S2: and (5) preparing glue. The system is glued including electrically conductive PU coating glue preparation and nylon resin glue preparation, wherein: when the conductive PU coating adhesive is prepared, firstly adding methanol into a reaction pot according to a certain proportion, starting stirring, slowly adding PU resin, nano conductive carbon black powder and the like, keeping the temperature of the reaction pot at 60-62 ℃ and continuously reacting for 6-8 hours, and then filtering and discharging by using a filter screen; when the nylon resin adhesive is prepared, firstly adding ethanol into a reaction kettle, stirring and slowly adding nylon particles, heating to 60-70 ℃ to dissolve the nylon particles, then slowly adding solvents such as formaldehyde, continuously reacting for 2 hours at 60-70 ℃, cooling, placing into an aluminum barrel, washing with cold water to separate precipitates, then pouring the precipitates into an aluminum tray to dry, and preparing the precipitates into a solution with a certain concentration for later use to form a semi-finished solution; dissolving resin in an ethanol solution according to a certain concentration, controlling the temperature at 50-60 ℃, mixing the semi-finished product solution and the resin solution according to a certain proportion at 40-50 ℃, uniformly stirring, slightly cooling, adding an accelerant, and uniformly stirring.

Step S3: and (6) gluing. The coating comprises coating a conductive PU coating adhesive on the polyester non-woven fabric composite surface of the velveteen surface and coating a nylon resin adhesive on the two surfaces of a nylon sheet base, wherein: when the polyester non-woven fabric composite surface of the plain velvet surface is coated, the temperature of an oven is controlled to be 160-180 ℃, the polyester non-woven fabric composite surface of the plain velvet surface is uniformly coated with glue, and the frosted surface is kept clean; when the nylon sheet base is coated, the special flexibility treatment is firstly carried out, then the cleaning and the drying are carried out by butanone, the temperature of an oven is controlled to be 90-110 ℃, and the double surfaces of the nylon sheet base are uniformly coated with glue.

Step S4: and (4) compounding. And after the nylon base sheet is taken out of the oven, the two sides of the nylon base sheet are both covered with polyester non-woven fabrics with plain velvet surfaces, the upper layer and the lower layer are aligned, and the polyester non-woven fabrics with plain velvet surfaces cover the nylon base sheet. When the continuity is compounded, the belt body needs to be kept in a tensioning state, the surface is clean and flat, and the belt body needs to be fully cooled when the last vehicle is vulcanized or the machine is stopped midway, and the pressure is released.

Step S5: and (5) cutting. And (3) trimming the reference edge of the belt body by taking one side of the nylon sheet as the reference, cutting according to the size by taking the reference edge as the positive side, and grinding the joint.

Step S6: and (6) gluing. After cleaning the joints, respectively coating corresponding glue on the polyester non-woven fabric and the nylon sheet base with the velveteen surface, drying, and performing involution and cold pressing; when the joint is hot pressed, two layers of canvas and one layer of polypropylene fabric are respectively padded up and down.

Step S7: and (7) grinding the belt. And after the connector is unloaded, cleaning and arranging the connector.

Step S8: and (7) checking and warehousing. And (5) spraying and printing corresponding information on the belt body, and packaging and warehousing after inspection.

Before the material preparation, whether the varieties of various raw materials are consistent or not and whether the varieties are qualified or not are checked, unqualified raw materials cannot be put into use, and the material preparation requirement is accurate.

In step S3, when the polyester non-woven fabric composite surface with the velveteen surface is coated, the polyester non-woven fabric composite surface should be covered with a plastic film and rolled up after being taken out of the oven.

In step S4, the polyester non-woven fabric with a velvety surface and the nylon substrate are blended according to the thickness of the tape blank as follows:

thickness of belt blank (mm)	Rubberized fabric thickness (mm)	Nylon base thickness (mm)
			1.0	0.35mm polyester non-woven fabric with plain velvet surface	0.3
1.2	0.4mm polyester non-woven fabric with plain velvet surface	0.4
			1.5	0.5mm polyester non-woven fabric with plain velvet surface	0.5
2.0	0.6mm polyester non-woven fabric with plain velvet surface	0.8
			3.0	1.0mm polyester non-woven fabric with plain velvet surface	1.0

The compounding process is as follows:

thickness (mm)	Temperature (. degree.C.)	Time (min)	Automatic compound line pressure (MPa)	Pressure of No. 2 drum sulfur machine (MPa)
					1.0-1.2	90～95	6	6	8
1.5	100～103	8	6	8
					2.0-3.0	105～110	9～11	9	10

In step S5, cutting width error is-0.2 mm, length is measured and a joint line is drawn at an angle of 60 degrees according to the thickness and the width of the belt; the grinding joints are laid flat, the inclined plane keeps flat and uniform in thickness, when the two joints are closed, the polyester non-woven fabric with the flat velvet surface is matched with the polyester non-woven fabric with the flat velvet surface, the nylon sheet base is matched with the nylon sheet base, the thickness of the joints is not lower than that of the belt body, and the error is +0.1 mm. Wherein, belt thickness and joint length correspond as follows:

leather belt thickness (mm)	1.0	1.2	1.5	2.0	3.0
						Joint length (mm)	30	40	50	60	75

In step S6, when the joints are aligned, the respective portions are aligned, the joints do not overlap or collapse, and the straightness is ensured, and the hot pressing conditions are as follows:

holding temperature (. degree.C.)	Incubation time (min)	Pressure (MPa)	Lower machine temperature (. degree.C.)
				90～100	45	3.5～4	Less than 40

In step S8, the information on the jet printing includes the specification, the date of manufacture, and the direction of operation.

The working principle is as follows: the preparation method comprises the steps of preparing a polyester non-woven fabric with a plain velvet surface and a nylon sheet base at the same time, sanding and slitting the polyester non-woven fabric with the plain velvet surface, and performing flexibility treatment on the nylon sheet base. The system is glued, and the system is glued including electrically conductive PU coating glue preparation and nylon resin glue preparation, wherein: when the conductive PU coating adhesive is prepared, firstly adding methanol into a reaction pot according to a certain proportion, starting stirring, slowly adding PU resin, nano conductive carbon black powder and the like, keeping the temperature of the reaction pot at 60-62 ℃, continuously reacting for 6-8 hours, and then filtering and discharging by using a filter screen; when the nylon resin adhesive is prepared, firstly adding ethanol into a reaction kettle, starting stirring, slowly adding nylon particles, heating to 60-70 ℃ to dissolve the nylon particles, then slowly adding solvents such as formaldehyde, continuously reacting for 2 hours at 60-70 ℃, cooling, placing into an aluminum barrel, washing with cold water, separating precipitates, then pouring the precipitates into an aluminum tray for airing, and preparing the precipitates into a solution with a certain concentration for later use to form a semi-finished solution; dissolving resin in an ethanol solution according to a certain concentration, controlling the temperature at 50-60 ℃, mixing the semi-finished product solution and the resin solution together according to a certain proportion at 40-50 ℃, uniformly stirring, slightly cooling, adding an accelerant, and uniformly stirring. And gluing, wherein the gluing comprises coating a conductive PU coating on the composite surface of the polyester non-woven fabric with a velveteen surface and coating nylon resin adhesive on the two surfaces of a nylon sheet base, and the coating comprises the following steps: when the polyester non-woven fabric composite surface with the flat velvet surface is coated, the temperature of an oven is controlled to be 160-180 ℃, the coating of the polyester non-woven fabric composite surface with the flat velvet surface is uniform, the frosted surface is kept clean, and when the polyester non-woven fabric composite surface with the flat velvet surface is coated, a plastic film is covered and wound neatly after the polyester non-woven fabric composite surface with the flat velvet surface is taken out of the oven; when the nylon sheet base is coated, the special flexibility treatment is firstly carried out, then the cleaning and the drying are carried out by butanone, the temperature of an oven is controlled to be 90-110 ℃, and the double surfaces of the nylon sheet base are uniformly coated with glue. And compounding, namely covering plain velvet polyester non-woven fabrics on two sides of the nylon sheet base after the nylon sheet base is taken out of the oven, wherein the upper layer and the lower layer are aligned, and the plain velvet polyester non-woven fabrics cover the nylon sheet base. When the continuity is compounded, the belt body needs to be kept in a tensioning state, the surface is clean and flat, and the belt body needs to be fully cooled when the last vehicle is vulcanized or the machine is stopped midway, so that the pressure relief is released. Cutting, taking one side of the nylon sheet as a reference, trimming a reference edge of the belt body, taking the reference edge as a positive side, cutting according to the size, and grinding the joint. Gluing, cleaning joints, respectively coating corresponding glue on polyester non-woven fabrics and nylon sheet substrates on the velveteen surface, drying, and performing involution and cold pressing; when the joint is hot pressed, two layers of canvas and one layer of polypropylene fiber cloth are respectively padded up and down. When the connectors are aligned, all parts are aligned, the connectors do not overlap or collapse, and the straightness is guaranteed. And (5) grinding the belt, and cleaning and tidying the joints after the belt is off the machine. And (5) inspecting and warehousing, namely spraying and printing corresponding specification, production date and running direction information on the belt body, and packaging and warehousing after inspection.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.