Sensor clamp for SMT silk-screen printing automatic feeding system and feeding system

Abstract

The invention discloses a sensor clamp for an SMT silk-screen printing automatic feeding system and the feeding system.The sensor clamp comprises a plurality of clamp units arranged in an array mode, and each clamp unit comprises a base serving as a supporting body of the clamp unit; the workpiece bearing table is fixed to the upper portion of the base and provided with a guide rail and a suction cup device, and the suction cup device comprises a plurality of suction holes connected with an exhaust fan; the positioning sliding block sets are symmetrically arranged and comprise fixed sliding blocks and movable sliding blocks, the fixed sliding blocks are fixedly connected with the base, and sliding connectors matched with the guide rails are formed in the bottoms of the movable sliding blocks; the spring reset mechanism is connected with the movable sliding block and the workpiece bearing table and used for automatically resetting the movable sliding block after the air cylinder assembly shrinks. The air cylinder assembly is arranged on the outer side of the movable sliding block, and a piston rod of the air cylinder assembly directly faces the movable sliding block to provide clamping thrust. The problems that in the prior art, a three-dimensional sensor is low in fixing efficiency, poor in adaptability and insufficient in positioning precision are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of surface mount technology (SMT), and particularly to a sensor fixture and a feeding system for an SMT screen printing automatic feeding system. Background Art

[0002] In the electronic manufacturing industry, as a key component, the performance of a three-dimensional sensor is closely related to the manufacturing process. The printing of solders such as solder paste is an important link in connecting the sensor and the circuit board. However, the diversity of different-shaped three-dimensional sensor workpieces poses a severe challenge to solder printing. At the same time, to ensure the accuracy and efficiency of printing, the application of high-speed and precise positioning technology has become the core of solving the problem.

[0003] Traditional SMT production lines are mainly designed for flat PCB boards, and their fixtures are mostly of fixed structures. The existing technologies have the following problems:

[0004] Currently, the main printing problems brought by three-dimensional sensor components are as follows: 1. The shapes of three-dimensional sensor components are diverse, and traditional fixtures cannot be flexibly adjusted to fix sensor components with different geometric structures, making it difficult to perform batch printing; 2. The sizes of different types of sensor components are inconsistent, making it difficult to quickly and precisely adapt to different sizes; 3. In actual production, the printing process needs to be carried out at high speed, but the vibration generated by high-speed printing or unstable clamping will cause errors in the positioning of sensor components, resulting in a decrease in accuracy. 4. Manual feeding and single-piece fixing modes are difficult to meet the requirements of batch production, increasing labor costs and time costs.

[0005] Therefore, in order to solve the industrial problem of efficiently printing solders such as solder paste on different-shaped three-dimensional sensor workpieces and solve the problem of high-speed and precise positioning, there is an urgent need for a sensor fixture and a feeding system with high precision, high efficiency, and strong adaptability. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention proposes a sensor fixture and a feeding system for an SMT screen printing automatic feeding system, which solves the problems of low fixing efficiency, poor adaptability, and insufficient positioning accuracy of three-dimensional sensor components in the prior art.

[0007] To achieve the above technical objectives, on the one hand, the present invention proposes a sensor fixture for an SMT screen printing automatic feeding system, which includes a plurality of fixture units arranged in an array, and each fixture unit includes:

[0008] A base, serving as the supporting body of the fixture unit, is provided with an air extraction port for adsorbing processing debris;

[0009] A workpiece supporting table, fixed above the base, and its upper surface is provided with a guide rail;

[0010] A symmetrically arranged positioning slider group, including a fixed slider and a movable slider. The fixed slider is fixedly connected to the base, and a sliding interface matching the guide rail is provided at the bottom of the movable slider;

[0011] A spring reset mechanism, connecting the movable slider and the workpiece support table, for automatically resetting the movable slider after the cylinder assembly contracts;

[0012] A cylinder assembly, arranged outside the movable slider, and its piston rod provides a clamping thrust facing the movable slider.

[0013] Furthermore, positioning notches adapted to the shape of the sensor element are provided on the opposite sides of the positioning slider group.

[0014] Furthermore, the positioning notch is V-shaped, the working angle α of the notch is 90°, and the positioning error Δy satisfies:

[0015] Δy = ((D + d) / 2)*[1 / sin(α / 2) - 1]; where: D is the maximum diameter of the sensor element, 12.01 mm, d is the minimum diameter of the sensor element, 11.99 mm, and calculating gives Δy = 0.0071 mm.

[0016] Furthermore, the movable slider is also provided with an anti-collision groove, and the depth matches the thickness of the side wall of the workpiece support table.

[0017] Furthermore, the spring reset mechanism is a circular spring; the movable slider is also provided with a spring connection groove, and the depth is equal to the fully compressed length L' of the spring.

[0018] Furthermore, a suction cup device is provided on the workpiece support table. The suction cup device includes a plurality of adsorption holes provided on the workpiece support table, a suction port is provided on the fixed slider to set a leather tube, one end of the leather tube is connected to the adsorption hole, and the other end is connected to a suction fan.

[0019] The present invention also discloses an SMT screen printing automatic feeding system, including the above-mentioned sensor fixture, and further including:

[0020] A support frame, on which a conveying device and a three-axis robotic arm are installed; the conveying device is installed on the support frame for conveying a fixture fixing plate carrying the sensor fixture; the fixture fixing plate is an open box structure at the top and is installed with a plurality of fixture units in an array; the three-axis robotic arm is installed above the conveying device for grasping the sensor element and placing it into the sensor fixture;

[0021] A fully automatic screen printing machine, the material inlet of which is connected to the conveying device for feeding.

[0022] Further, the conveying device includes a material bin, a conveyor belt and a motor; the motor provides power to transport the fixture fixing plate from the discharge port of the material bin to the fully automatic screen printing machine and finally complete the printing work.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] In the present invention, the sensor fixture for the SMT screen printing automatic loading system is a key component for mass production of this production line; the fixture fixing plate is equipped with an array of fixture units, and the fixture unit selects a positioning slider group, and provides stable stress output through a cylinder assembly and a spring reset mechanism, and controls the initial positioning accuracy of the sensor device within ±0.007 mm, providing a precise starting position basis for the subsequent printing process. The fixture fixing plate is placed in the material bin to ensure that the entire system maintains stable accuracy during continuous feeding, effectively reducing printing quality problems caused by inconsistent positioning and improving the printing yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0026] Figure 1 Shows the front view of the sensor fixture in the present invention;

[0027] Figure 2 Shows the three-dimensional view of the sensor fixture in the present invention;

[0028] Figure 3 Shows the three-dimensional view of the base and fixed slider of the present invention;

[0029] Figure 4 Shows another angle three-dimensional view of the base and fixed slider of the present invention;

[0030] Figure 5 Shows the three-dimensional view of the movable slider of the present invention;

[0031] Figure 6 Shows the top view of the loading system of the present invention;

[0032] Figure 7 Shows the flowchart of the loading process of the present invention.

[0033] Among them, the above-mentioned drawings include the following reference numerals:

[0034] 1. Base; 2. Workpiece supporting table; 21. Suction cup device; 31. Fixed slider; 311. Air extraction port; 32. Movable slider; 321. Sliding interface; 322. Anti-collision groove; 323. Spring connection groove; 33. Positioning notch; 4. Spring reset mechanism; 5. Cylinder assembly; 6. Sensor component; 7. Support frame; 71. Conveyor belt; 72. Three-axis robotic arm; 8. Fixture fixing plate; 9. Fully automatic screen printing machine. Detailed implementation mode

[0035] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any form, that is, it is not intended to limit the protection scope of the present invention.

[0036] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0037] Embodiment 1

[0038] As Figures 1 to 4 shown, this embodiment discloses a sensor fixture for an SMT screen printing automatic loading system, which includes a plurality of fixture units. Each fixture unit includes a base 1, a workpiece supporting table 2, a positioning slider group, a spring reset mechanism 4 and a cylinder assembly 5;

[0039] The base 1 serves as the supporting main body of the fixture unit;

[0040] The workpiece supporting table 2 is located above the base 1 and is used for placing the sensor component 6; a guide rail is provided on the workpiece supporting table 2;

[0041] The positioning slider group includes a movable slider 32 and a fixed slider 31, which are symmetrically distributed on both sides of the workpiece supporting table 2; the bottom of the movable slider 32 is provided with an interface connected to the guide rail, so that under the drive of the cylinder assembly 5, the movable slider 32 can slide along the guide rail towards the side where the fixed slider 31 is located to clamp the sensor component 6; the fixed slider 31 is integrally fixed above the base 1.

[0042] Preferably, positioning notches 33 adapted to the shape of the sensor component 6 are symmetrically provided on the opposite sides of the movable slider 32 and the fixed slider 31;

[0043] The spring reset mechanism 4 is connected between the movable slider 32 and the workpiece supporting table 2 and is used to automatically reset the movable slider 32 after the cylinder assembly 5 contracts so as to unload the sensor component 6;

[0044] The cylinder assembly 5 is arranged outside the movable slider 32, and its cylinder piston rod faces the movable slider 32 to provide stable thrust to clamp the workpiece. Preferably, the cylinder assembly 5 is a single-acting cylinder, and the preferred model is MI32×15-S-U.

[0045] After the three-axis manipulator clamps the sensor device 6 into the fixture, it will be placed on the workpiece support table 2. At this time, due to errors generated during the clamping and placement process, the bottom surfaces of some sensor devices 6 cannot be completely attached to the workpiece support table 2, that is, the central axis of the sensor device 6 is not perpendicular to the fixture base 1. If fixed at this time, it will cause certain wear to the sensor device 6 itself, and even unable to clamp, resulting in irreversible damage to the fixture itself. Therefore, a suction cup device 21 is set in the workpiece support table 2. The suction cup device 21 includes a plurality of adsorption holes provided on the workpiece support table 2, and a suction port 311 is provided on the fixed slider 31 to set a leather tube. One end of the leather tube is connected to the adsorption hole, and the other end is connected to a suction fan, so as to form a stable effect on the workpiece and adsorb and fix the sensor device 6 in an inclined and unstable state. A suction port is provided on the fixed slider to set a leather tube. After the sensor device 6 is stably placed on the workpiece support table 2, the cylinder assembly 5 pushes the movable slider 32 to the maximum stroke, and the sensor device 6 is completely fixed under the action of the fixture. After processing is completed, the cylinder assembly 5 contracts, and the spring return mechanism 4 restores the movable slider 32 to the initial position, thus completing a clamping operation.

[0046] Embodiment 2

[0047] In this embodiment, the structure and parameters of the movable slider 32 are further described:

[0048] As Figure 5 shown, the positioning notch 33 is designed as a V shape; compared with positioning devices such as pin positioning, gear tooth shape positioning, and wedge positioning, the positioning of the movable slider 32 with the V-shaped positioning notch 33 has better positioning accuracy, which is consistent with the high-precision processing requirements of current electronic components. In addition, the V-shaped positioning notch 33 has a higher degree of fit for fixing cylindrical and disc-shaped sensor devices 6.

[0049] The positioning notch 33 is a key part for positioning the workpiece, and its positioning error is closely related to the working angle of the positioning notch 33. The working angle of the slider is inversely proportional to the positioning error, but too large a working angle will cause the positioning stability of the workpiece to deteriorate. Therefore, when designing the working angle of the slider, in order to balance its positioning accuracy and positioning stability, the working angle of the V-shaped positioning notch 33 is set to 90 degrees.

[0050] In addition, this positioning slider group can position cylindrical and disc-shaped sensor devices 6 with a diameter of 12±0.01 mm.

[0051] When the working angle of the V-shaped positioning notch 33 is α, the positioning error is:

[0052]

[0053] In the formula: D is the maximum diameter of the sensor device 6; d is the minimum diameter of the sensor device 6; α is the working angle of the V-shaped positioning notch 33;

[0054] When calculating the positioning error, in order to make the calculated positioning error distribution symmetrical, the D value in the formula can be taken as the middle size of the positioning surface, that is where D = 12.01 mm and d = 11.99 mm.

[0055] Substitute the parameters of the slider into Equation (1): The positioning error Δy = 0.0071 mm.

[0056] On the movable slider 32, there is a sliding interface 321 that is slidably matched with the guide rail, and there is also an anti-collision groove 322 that is adapted to the side shape of the workpiece supporting table 2, and its depth matches the thickness of the side wall of the workpiece supporting table 2. When the movable slider 32 presses against the sensor device 6, the anti-collision groove 322 can prevent the workpiece supporting table 2 from colliding with the movable slider 32 and enable the fixture to be clamped smoothly during operation.

[0057] On the movable slider 32, there is also a spring connection groove 323 for fixing one end of the spring return mechanism 4; preferably, the spring return mechanism 4 is a circular spring, and the depth L of the spring connection groove 323 is equal to the length L' after the spring is completely compressed, so that after the air cylinder stops working, the spring has enough elastic potential energy to stably push the movable slider 32 back to the starting position.

[0058] Example 3

[0059] This embodiment discloses the parameter design of the spring:

[0060] The spring used in this design needs to complete the work repeatedly, so a type of spring is selected, and 65Mn is initially selected as the spring material. 65Mn is a low-manganese spring steel with an elastic modulus of 75 Mpa and a shear modulus of 79 Gpa.

[0061] Table 1 Common values of the spring index C

[0062]

[0063] It can be seen from Table 1 that when the wire diameter d of the spring is 1.1 mm, the common spring index is 5.

[0064] The axial deformation λ of the cylindrical helical compression (tension) spring can be obtained according to Equation (2):

[0065]

[0066] Substitute the above data into Equation (2): λ = 12.84 mm is obtained;

[0067] That is, when a stress of 150 N is applied, the spring will produce an axial deformation of 12.84 mm. All the parts clamped in this design are sensor parts 6 with a diameter of 12 mm, so the requirements are met.

[0068] The spring stiffness represents the force required to produce a unit deformation of the spring, also known as the stiffness coefficient.

[0069] Substitute the designed spring parameters into Equation (3):

[0070]

[0071] K is obtained f = 9.66 N / mm;

[0072] According to Hooke's law, the force provided by the spring is the product of its stiffness coefficient and deformation, that is

[0073] Substitute the above results into Equation (4):

[0074] F 弹 = λK f (4);

[0075] F 弹 = 124.03 N.

[0076] Example 4

[0077] This example discloses the parameter design of the cylinder assembly 5:

[0078] Since the clamping fixture in this design is applicable to cylindrical and disc-shaped sensor parts 6 with a diameter of 10 mm, the size, power, etc. of the cylinder should not be too large. Secondly, the cylinder assembly 5 only needs to provide force for the one-way sliding of the movable slider 32, so the selection range is narrowed down to single-acting cylinders.

[0079] Table 2 MI Cylinder Parameters

[0080]

[0081] Table 2 shows the parameters of several small cylinders. Since during the processing, it is necessary to ensure that the cylinder stroke is larger than the theoretical stroke of the spring, and considering the actual space size of the cylinder, the MI32*15-S-U model cylinder is finally selected.

[0082] Example 5

[0083] As Figure 6As shown in the figure, this embodiment discloses a feeding system including the above-mentioned fixture unit, specifically including a full-automatic screen printing machine 9, a support frame 7, a conveying device, a three-axis robotic arm 72, and a workpiece operating table 10;

[0084] The full-automatic screen printing machine 9 is arranged on one side of the support frame 7, and the conveying device is installed on the support frame 7; the conveying device includes a material bin, a conveyor belt 71, and a motor; one end of the conveyor belt 71 is connected to the workpiece operating table for feeding, and the other end is connected to the material inlet of the full-automatic screen printing machine 9; the conveyor belt 71 is used to place the fixture fixing plate 8, and the fixture fixing plate 8 is preferably a box structure with an open top for fixing a plurality of fixture units in an array. The fixture fixing plate 8 is installed with 4×4 fixture units. In the actual production process, the specific processing quantity of this unit can be flexibly adjusted according to production requirements.

[0085] The three-axis robotic arm 72 is integrally installed on the support frame 7 above the conveyor belt 71; the movement of the robotic arm is realized by the mutual cooperation of three-dimensional motion groups in the X, Y, and Z directions. The motion groups are equipped with racks, guide rails, and drag chains to ensure the stability of the robotic arm movement and grasping. The CCD high-definition camera equipped at the grasping end of the three-axis robotic arm 72 takes images of the sensor device 6 to be processed, and then converts the image signal into an electrical signal and transmits it to the system to control the three-axis robotic arm 72 to perform the grasping operation; the three-axis robotic arm 72 provides the grasping force by a pneumatic claw, and the end of the pneumatic claw is a suction cup, which can grasp four sensor devices 6 at one time. The suction cup is made of NBR nitrile rubber, with excellent durability and convenient replacement, and can well meet the grasping work of small sensor devices 6.

[0086] The conveyor belt 71 is made of rubber material, which is light in weight, thin in belt body, and excellent in physical properties, and can meet the requirements of actual production; the motor provides power to transport the fixture fixing plate 8 from the discharge port of the material bin to the printing platform and finally complete the printing work.

[0087] After the fixture fixing plate 8 is transported from the upper plate opening to the printing platform of the full-automatic screen printing machine 9, the screen printing plate starts to perform positioning and fixing work. The screen printing plate of the full-automatic screen printing machine 9 and the fixture fixing plate 8 need to be used in a matching manner (4×4). After the fixing is completed, the squeegee works at a constant speed to ensure the printing quality and printing stability.

[0088] The working process of the SMT screen printing automatic feeding system is as Figure 7 shown.

[0089] In the present invention, the fixture unit is selected as a positioning slider group, and a stable stress output is provided by the cylinder assembly 5 and the spring reset mechanism 4, so that the initial positioning accuracy of the sensor device 6 is controlled within ±0.007 mm, providing an accurate starting position basis for the subsequent printing process. The fixture fixing plate 8 is placed in the material bin to ensure the stable accuracy of the whole system during continuous feeding, effectively reducing the printing quality problems caused by inconsistent positioning and improving the printing yield.

[0090] In this embodiment, the number of fixture units is 16, and 16 three-dimensional sensor devices 6 can be printed at one time. Each feeding process takes about 25 seconds, that is, 2300 three-dimensional sensor devices 6 are printed per hour.

[0091] It should be noted that the above content is a further detailed description of the present invention in combination with specific implementation manners, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions; the size data of this embodiment does not limit the technical solution, but only shows one specific working condition. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple improvements and retouches can be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A sensor fixture for SMT screen printing automatic feeding system, characterized in that: The invention comprises a plurality of fixture units arranged in an array, each fixture unit comprising: A base, serving as a supporting body of the fixture unit; The workpiece support platform is fixed above the base, and a guide rail is provided on its upper surface; A symmetrically arranged positioning slider group includes a fixed slider and a movable slider, wherein the fixed slider is fixedly connected to the base, and a sliding interface matching the guide rail is provided at the bottom of the movable slider; A spring return mechanism connects the movable slider and the workpiece support platform and is used to automatically return the movable slider after the cylinder assembly is retracted; The cylinder assembly is arranged outside the movable slide block, and its piston rod provides clamping thrust to the movable slide block.

2. The sensor fixture according to claim 1, characterized in that: The opposite side of the positioning slide block group is provided with a positioning notch matched with the shape of the sensor component.

3. The sensor fixture according to claim 2, characterized in that: The positioning notch is V-shaped, the notch working angle α=90°, and the positioning error Δy satisfies: Δy=((D+d) / 2)*[1 / sin(α / 2)-1]; where: D is the maximum diameter of the sensor device 12.01mm, d is the minimum diameter of the sensor device 11.99mm, and Δy=0.0071mm is calculated.

4. The sensor fixture according to claim 1, characterized in that: The movable slide block is also provided with an anti-collision groove, the depth of which matches the thickness of the side wall of the workpiece support platform.

5. The sensor fixture according to claim 1, characterized in that: The spring return mechanism is a circular spring; the movable slide block is also provided with a spring connection groove, the depth of which is equal to the fully compressed length of the spring.

6. The sensor fixture according to claim 1, characterized in that: The workpiece supporting platform is provided with a suction cup device, which includes a plurality of suction holes arranged on the workpiece supporting platform. The fixed slider is provided with an air exhaust port to set a leather hose, one end of the leather hose is connected to the suction hole, and the other end is connected to the exhaust fan.

7. An SMT screen printing automatic feeding system, characterized in that: A sensor fixture comprising any one of claims 1 to 6, and comprising: A support frame is provided with a conveying device and a three-axis robot arm; the conveying device is installed on the support frame and is used to transport a fixture fixing plate carrying a sensor fixture; the fixture fixing plate is provided with a plurality of fixture units installed in an array and has a box structure with an open top; the three-axis robot arm is installed above the conveying device and is used to grab the sensor device and place it in the sensor fixture; Fully automatic screen printing machine, the material inlet is connected to the conveyor device for easy loading.

8. The SMT screen printing automatic feeding system according to claim 7, characterized in that: The conveying device includes a material bin, a conveyor belt and a motor; the motor provides power to transport the fixture fixing plate from the material bin outlet to the fully automatic screen printing machine, and finally completes the printing work.

Images