A micro drill driving head for PCB board processing

Abstract

The present invention provides a micro-drill drive head for PCB board processing, which belongs to the field of precision machinery technology. It includes a housing, an intermediate sleeve, a plunger and a high-pressure air source, the intermediate sleeve is fixed in the housing, an air inlet channel is formed between the outer wall of the intermediate sleeve and the inner wall of the housing, the upper end of the plunger has a piston rotatably connected to the inner wall of the intermediate sleeve, the middle part of the plunger has an impeller, a driving air cavity is formed between the plunger and the intermediate sleeve, the intermediate sleeve has a plurality of air inlet holes connecting the driving air cavity and the air inlet channel, the plunger has an air flow reciprocating channel with the upper end penetrating the upper end face of the plunger, a pressurized air cavity connecting the air flow reciprocating channel is formed between the lower end face of the cover plate and the upper end face of the plunger, and the middle part of the plunger is provided with a plurality of functional holes connecting the air flow reciprocating channel, the functional holes can connect the outside world with the air flow reciprocating channel when the plunger is downward, and the functional holes can connect the driving air cavity with the air flow reciprocating channel when the plunger is upward. The present invention has the advantages of high operating efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of precision machinery and relates to a micro drill driving head for PCB board processing. Background Art

[0002] PCB board, also known as printed circuit board, is an important electronic component, a support for electronic components and a carrier for electrical connections. With the rapid development of highly integrated circuit boards, PCB boards are becoming smaller, thinner and more precise. The micro screwdrivers, milling cutters and other drills used for drilling holes and milling grooves are also becoming more refined, and the requirements for the drive mechanism that controls the rotation and extension of the drill are also getting higher and higher.

[0003] Specifically, the refinement of the drill bit reduces its strength, and problems such as easy breakage, easy damage, and easy deformation seriously affect the service life of the drill bit; the traditional drill bit drive mechanism is an integration of multiple control mechanisms, which is suitable for automated production and occupies a large space. It generally includes a rotation drive unit that drives the micro-drill to rotate and a feed drive unit that controls the longitudinal feed / exit of the micro-drill. In the automated production process, not only do the two drive units need to be coordinated, but in order to reduce the impact force of the drill bit, the drill bit always maintains a certain rotation speed, and realizes continuous processing of the PCB board through longitudinal reciprocating motion and translation and switching of the PCB board. The drill bit is always in a high-heat, high-intensity operating state, which has a great impact on the service life of the drill bit.

[0004] In addition, during the processing, whether it is feeding or exiting the drill, the drill bit directly contacts the PCB board at a relatively constant high speed (ignoring the change in speed when contacting the board, it can be assumed that its speed is constant). This contact mode causes the following problems: 1) The instantaneous cutting heat causes local thermal deformation of the PCB processing area; 2) The large impact force will increase the difficulty of PCB positioning and the misalignment of the PCB board (especially the positioning strength of the micro PCB board will not be too high during the processing); 3) Since there is no longitudinal buffer between the PCB board and the drill bit, the PCB board is "cut" with high strength, resulting in large burrs / burrs on the edges of the holes or slots of the PCB board, which usually require secondary repair and deburring, which affects the processing efficiency, It has a negative impact on both machining accuracy and quality; 4) In the early stage of cutting, since the micro-drill has not yet achieved "threading" between the micro-drill and the plate, the resistance at the end of the micro-drill has a negative impact on the coaxiality, which can easily cause severe wear, chipping and breakage of the cutter head. Due to the existence of the front angle, back angle, edge angle and spiral angle of the micro-drill, the micro-drill is subjected to greater stress that deviates from the axis, and the middle section of the micro-drill is prone to deformation. Once the coaxiality is affected, the service life and machining accuracy of the micro-drill will be greatly affected.

[0005] Heat dissipation is also an important factor in extending the service life of the micro drill. The existing equipment that drives the micro drill to rotate does not have a means to effectively dissipate heat for the micro drill. Summary of the invention

[0006] The purpose of the present invention is to provide a micro drill drive head for PCB board processing in view of the above-mentioned problems existing in the prior art. The technical problem to be solved by the present invention is to realize the rotation of the micro drill by pneumatic means while maintaining a small reciprocating motion to improve the working efficiency and reduce the impact.

[0007] The object of the present invention can be achieved through the following technical solutions: a micro drill driving head for PCB board processing, characterized in that it includes a shell, an intermediate sleeve, a plunger and a high-pressure gas source, the intermediate sleeve is fixed in the shell, an air inlet channel is formed between the outer wall of the intermediate sleeve and the inner wall of the shell, the upper end of the plunger has a piston rotatably connected to the inner wall of the intermediate sleeve, the middle part of the plunger has an impeller, a driving air cavity is formed between the plunger and the intermediate sleeve, the intermediate sleeve has a plurality of air inlet holes connecting the driving air cavity and the air inlet channel, the plunger has an air flow reciprocating channel with the upper end penetrating the upper end face of the plunger, the top of the intermediate sleeve is fixedly connected with a cover plate that blocks the upper end opening of the intermediate sleeve, a pressurized air cavity connecting the air flow reciprocating channel is formed between the lower end face of the cover plate and the upper end face of the plunger, the middle part of the plunger is provided with a plurality of functional holes connecting the air flow reciprocating channel, the functional holes can connect the outside world with the air flow reciprocating channel when the plunger is downward, and the functional holes can connect the driving air cavity with the air flow reciprocating channel when the plunger is upward; the lower end of the plunger has a micro drill mounting head.

[0008] Furthermore, the impeller includes a plurality of flow-guiding ribs uniformly arranged in the middle of the plunger in the circumferential direction, and the flow-guiding ribs are spiral-shaped.

[0009] Furthermore, the diameter of the impeller gradually decreases from top to bottom.

[0010] Furthermore, the air inlet holes are evenly distributed on the intermediate sleeve in the circumferential direction, and an acute angle is formed between the axis of the air inlet hole and the radial line of the intermediate sleeve.

[0011] Furthermore, the upper end of the shell has a connecting pipe connected to the air intake channel, and the high-pressure air source is directly or indirectly connected to the connecting pipe.

[0012] The working process is as follows:

[0013] The plunger moves upward, and the micro-drill rotates to cut out: at this time, the functional hole is connected to the outside world, the driving air cavity and the pressurized air cavity are isolated, and the air flow passes through the high-pressure air source, the connecting pipe, the air inlet channel, and the air inlet hole. When the high-pressure air flow enters the driving air cavity from the air inlet hole, the high-pressure air flow acts on the impeller, causing the plunger to rotate while the volume of the driving air cavity increases, causing the plunger to move upward. The plunger stops moving upward when the functional hole and the driving air cavity are connected and the upward inertia force of the plunger is overcome. The corresponding working state of the micro-drill is: after completing the hole opening and other processing, the micro-drill slowly rotates and moves upward to cut out until the micro-drill is separated from the PCB board.

[0014] The plunger moves downward, and the micro-drill rotates and feeds: at this time, the functional hole connects the driving air cavity and the pressure air cavity, and the air flow passes through the high-pressure air source, the pipe, the air inlet channel, the air inlet hole, the driving air cavity, the functional hole, the air flow round-trip channel and the pressure air cavity. Since the pressure surface of the plunger in the pressure air cavity is larger than the pressure surface of the plunger in the driving air cavity, that is, the pressure surface of the upper end of the plunger is the upper end surface of the piston, and the pressure surface of the middle part of the plunger that drives the plunger upward is the difference between the middle section of the plunger and the piston section, the plunger is subjected to a larger downward pressure from the pressure air cavity and moves downward. During the downward process of the plunger, the pressure air cavity expands greatly, the air flow is large, and the air flow acts on the impeller to rotate the impeller and the plunger. The torque is large, and the plunger rotates at high speed and moves downward. When the functional hole is connected to the outside world, the downward pressure of the plunger decreases instantly and gradually stops moving downward. The corresponding working state of the micro-drill is: the action time limit of the micro-drill moving downward and rotating at high speed limits the feeding of the micro-drill to process the PCB board.

[0015] Exhaust: When the plunger moves down to the middle sleeve of the functional hole, the pressure in the pressurized air cavity is relieved, and the air flows through the pressurized air cavity, the air flow round-trip channel, and the functional hole, and the functional hole is connected to the outside world to relieve pressure and exhaust. The setting of the overflow channel can extend the retraction interval after the plunger moves down, so that the micro-drilling speed drops to a low level before moving up.

[0016] The plunger and the micro drill connected to the lower end of the plunger cycle in the following working states: fast rotation and downward movement for feeding operation, slow rotation and upward movement to complete the cutting operation.

[0017] Since the impeller is a cone with a larger diameter at the upper end than at the lower end, during the downward movement of the plunger, the gap between the impeller and the intermediate sleeve gradually decreases, the force surface of the impeller gradually increases, and the airflow that does not participate in driving the impeller gradually decreases, so that the rotation speed of the plunger gradually increases, and the speed is changed from slow to fast to process the PCB board, so as to reduce the impact of the micro-drill on the PCB board and reduce the impact force between the tool and the PCB board before the micro-drill enters the PCB board, which can greatly eliminate the damage to the tool and the rapid temperature rise caused by high-speed cutting; during the upward movement of the plunger, the gap between the impeller and the intermediate sleeve gradually increases, the force surface of the impeller gradually decreases, and the airflow that does not participate in driving the impeller gradually increases, so that the rotation torque of the plunger gradually decreases, and the speed is changed from fast to slow to realize the removal of the tool after the micro-drill processes the PCB board.

[0018] Since the upward and downward movement and rotation of the drive head are both "soft-driven", the impact force is small, and the speed of the plunger remains continuous and gradual during the up and down movement, and the rotation speed also maintains a gradual change that matches the work needs, which greatly reduces the duration of the plunger's working cycle, thereby improving the processing efficiency during the automated processing process.

[0019] Compared with the existing micro-drill drive method, this micro-drill drive head has the following advantages:

[0020] 1. Connect the housing to the machine tool or the robot execution end, and connect the high-pressure air source through the pipe, so as to realize the separation between the power source (air pump) and the drive head, which greatly improves the operating space of the drive head, reduces the space occupied by the drive head, reduces the load-bearing of the robot execution arm, simplifies the online structure of the automated production line, and can realize multi-point synchronous processing with greater density for the processing of small-size PCB boards.

[0021] 2. In response to the trend of PCB boards becoming smaller and thinner, this drive head can achieve "high-frequency and small-width" operation. "Small-width" means that the feed distance required for thin plate processing is small; in the automated production process, multiple machines can operate on one board at the same time.

[0022] 3. The plunger and the micro-drill connected to the plunger are not in rigid contact with the driving parts during the entire working process. The soft contact mode during the whole process can reduce the probability of wear, heating, and tool breakage of the micro-drill, extend the service life of the tool, and is also an indirect manifestation of further improving operating efficiency.

[0023] 4. This drive head can be used for processing with micro drills with smaller diameters. Due to the smaller impact, the weakening of the strength of the small-sized micro drill will not significantly affect the operating quality and service life of the micro drill.

[0024] 5. This drive head realizes high-frequency air cooling of the micro drill, reduces the heat collection of the micro drill, and with the fully enclosed structure of the drive head, it can eliminate the influence of machining chips on the drive head.

[0025] 6. The cross-section of the overflow channel is larger at the beginning of pressure relief, and gradually decreases during the continuous pressure relief process, so as to maintain relatively stable air-cooling pressure and impurity-removing airflow during the pressure relief process, and avoid splashing of slag caused by excessive pressure changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure when the drive head is installed with a micro drill.

[0027] Figure 2 It is a structural schematic diagram of the drive head when the plunger moves downward (or upward) until the functional hole is covered by the adjusting sleeve.

[0028] Figure 3It is a schematic diagram of the structure of the drive head when the plunger moves downward to the limit position.

[0029] Figure 4 It is a schematic diagram of the structure of the drive head when the plunger moves upward to the limit position.

[0030] Figure 5 yes Figure 2 Cross-sectional view along the AA direction.

[0031] In the figure, 1. shell; 11. connecting pipe; 2. intermediate sleeve; 21. cover plate; 3. plunger; 31. piston; 32. impeller; 321. guide rib; 33. micro drill mounting head; 4. adjusting sleeve; 41. guide cavity; 42. overflow channel; 43. limit buffer pad; 51. air inlet channel; 52. driving air cavity; 53. air inlet hole; 54. air flow round-trip channel; 55. functional hole; 56. pressurized air cavity; 6. micro drill. DETAILED DESCRIPTION

[0032] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0033] like Figure 1 and Figure 2 As shown, the driving head includes a shell 1, an intermediate sleeve 2, a plunger 3 and a high-pressure gas source. The intermediate sleeve 2 is fixed in the shell 1, and an air inlet channel 51 is formed between the outer wall of the intermediate sleeve 2 and the inner wall of the shell 1. The upper end of the plunger 3 has a piston 31 rotatably connected to the inner wall of the intermediate sleeve 2, and the middle part of the plunger 3 has an impeller 32. An adjusting sleeve 4 is connected between the lower end of the plunger 3 and the intermediate sleeve 2. The adjusting sleeve 4 and the intermediate sleeve 2 are threadedly connected, and the adjusting sleeve 4 and the plunger 3 are slidably connected. A driving air cavity 52 is formed between the upper end of the adjusting sleeve 4 and the lower end of the piston 31. The intermediate sleeve 2 has a plurality of air inlet holes 53 connecting the driving air cavity 52 and the air inlet channel 51. The plunger 3 has an air flow reciprocating channel 54 with the upper end penetrating the upper end surface of the plunger 3. The top of the intermediate sleeve 2 is fixedly connected to a cover plate 21 for blocking the upper end opening of the intermediate sleeve 2, and the lower end surface of the cover plate 21 is connected to the plunger 3. A pressurized air cavity 56 connected to the reciprocating air flow channel 54 is formed between the upper end surfaces. A plurality of functional holes 55 connected to the reciprocating air flow channel 54 are provided in the middle of the plunger 3. The functional holes 55 can connect the outside with the reciprocating air flow channel 54 when the plunger 3 moves downward, and the functional holes 55 can connect the driving air cavity 52 with the reciprocating air flow channel 54 when the plunger 3 moves upward. The lower end of the plunger 3 is provided with a micro-drill mounting head 33.

[0034] like Figure 5As shown, the impeller 32 includes a plurality of flow guide ribs 321 uniformly arranged in the middle of the plunger 3 in the circumferential direction, and the flow guide ribs 321 are spiral. The diameter of the impeller 32 gradually decreases from top to bottom. The air inlet holes 53 are uniformly distributed on the intermediate sleeve 2 in the circumferential direction, and the axis of the air inlet hole 53 forms an acute angle with the radial line of the intermediate sleeve 2.

[0035] A guide cavity 41 is formed between the inner wall of the lower end of the adjusting sleeve 4 and the outer wall of the lower end of the plunger 3. An annular overflow channel 42 is formed between the lower end of the guide cavity 41 and the outer wall of the plunger 3. The guide cavity 41 is an annular cavity with a gradually decreasing aperture from top to bottom.

[0036] The upper end of the housing has a connecting pipe 11 connected to the air inlet channel 51, and the high-pressure air source is directly or indirectly connected to the connecting pipe 11. The upper end surface of the adjusting sleeve 4 has a limiting buffer pad 43 made of rubber material.

[0037] The working process is as follows:

[0038] The plunger 3 moves upward, and the micro-drill 6 rotates to cut out: at this time, the functional hole 55 connects the guide cavity 41 and the outside world, and the driving air cavity 52 and the pressurized air cavity 56 are isolated. The air flows through the high-pressure air source, the connecting pipe 11, the air inlet channel 51, and the air inlet hole 53. When it enters the driving air cavity 52 from the air inlet hole 53, the high-pressure airflow acts on the impeller 32, causing the plunger 3 to rotate while the volume of the driving air cavity 52 increases, causing the plunger 3 to move upward. The plunger 3 stops moving upward when the functional hole 55 is connected to the driving air cavity 52 and overcomes the upward inertia force of the plunger 3. The corresponding working state of the micro-drill 6 is: after completing the hole opening and other processing, the micro-drill cuts out by slowly rotating and moving upward until the micro-drill is separated from the PCB board. The intermediate process is as follows: Figure 2 As shown, the extreme position is shown in Figure 4.

[0039] The plunger 3 moves downward, and the micro drill 6 rotates and feeds: at this time, the functional hole 55 connects the driving air chamber 52 and the pressure air chamber 56, and the air flows through the high-pressure air source, the connecting pipe 11, the air inlet channel 51, the air inlet hole 53, the driving air chamber 52, the functional hole 55, the air flow round-trip channel 54 and the pressure air chamber 56. Since the pressure surface of the plunger 3 in the pressure air chamber 56 is larger than the pressure surface of the plunger 3 in the driving air chamber 52, that is, the pressure surface of the upper end of the plunger 3 is the upper end surface of the piston 31, and the pressure surface of the middle part of the plunger 3 that drives the plunger 3 upward is the middle section of the plunger 3 and the piston 31. The difference in cross-section causes the plunger 3 to move downward due to the greater downward pressure from the pressurized air chamber 56. During the downward movement of the plunger 3, the pressurized air chamber 56 expands greatly, the airflow is large, and the airflow acts on the impeller 32 to cause the impeller 32 and the plunger 3 to rotate with a greater torque. The plunger 3 rotates at high speed and moves downward. When the functional hole 55 is connected to the guide cavity 41 and the outside world, the downward pressure on the plunger 3 decreases instantly and the plunger 3 gradually stops moving downward. The corresponding working state of the micro-drill is: the micro-drill 6 moves downward at high speed and rotates during the action time limit of the micro-drill feed, and the PCB board is processed. The intermediate process is shown in Figure 2, and the extreme position is as shown in Figure 2. Figure 3 shown.

[0040] Exhaust cooling: When the plunger 3 moves downward to the functional hole 55 and communicates with the guide cavity 41, the pressure in the pressurized air cavity 56 is released, and the airflow enters the guide cavity 41 through the pressurized air cavity 56, the airflow round-trip channel 54, and the functional hole 55, and is discharged from the overflow channel. The airflow acts on the micro-drill handle from top to bottom, and the handle and the cutter head below the handle are cooled by air. The setting of the overflow channel 42 can extend the retraction interval after the plunger 3 moves downward, so that the micro-drill 6 can move upward after the speed drops to a lower level.

[0041] The plunger 3 and the micro drill connected to the lower end of the plunger 3 cycle through the following working states: fast rotation and downward movement for feeding operation, slow rotation and upward movement to complete the cutting operation.

[0042] Since the impeller 32 is a cone with a diameter at the upper end larger than that at the lower end, during the downward movement of the plunger 3, the gap between the impeller 32 and the intermediate sleeve 2 gradually decreases, the force surface of the impeller 32 gradually increases, and the airflow that does not participate in driving the impeller 32 gradually decreases, so that the rotation speed of the plunger 3 gradually increases, and the PCB board is processed from slow to fast speed to reduce the impact of the micro drill on the PCB board, and reduce the impact force between the tool and the PCB board before the micro drill enters the PCB board, which can greatly eliminate tool damage and rapid temperature rise caused by high-speed cutting; during the upward movement of the plunger 3, the gap between the impeller 32 and the intermediate sleeve 2 gradually increases, the force surface of the impeller 32 gradually decreases, and the airflow that does not participate in driving the impeller 32 gradually increases, so that the rotation torque of the plunger 3 gradually decreases, and the speed changes from fast to slow to achieve the micro drill after the PCB board is processed.

[0043] The adjusting sleeve 4 can change the position of the limit buffer pad 43 relative to the middle sleeve 2 by rotating, so that the downward limit position of the plunger 3 is changed, that is, the timing of the functional hole 55 connecting to the guide chamber 41 is changed, thereby realizing the adjustment of the longitudinal reciprocating amplitude of the plunger 3; when a fault occurs, the plunger 3 moves downward to the limit position, and the lower end of the impeller 32 contacts the limit buffer pad 43 to stop the plunger 3 from moving downward. During normal working, since the pressure chamber has been depressurized when the plunger 3 moves downward and approaches the limit position, the pressure on the limit buffer pad 43 will not be very large. The contact-free state between the limit buffer pad 43 and the impeller 32 can be achieved by adjusting the air pressure and the position of the adjusting sleeve 4.

[0044] Since the up and down movement and rotation of the drive head are both "soft-driven", the impact force is small, and the speed of the plunger 3 remains continuous and gradual during the up and down movement, and the rotation speed also maintains a gradual change that matches the work needs, which greatly reduces the duration of the working cycle of the plunger 3, thereby improving the processing efficiency during the automated processing process.

[0045] During installation, install the micro drill first, then install the adjustment sleeve.

[0046] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A micro drill driving head for PCB board processing, characterized in that: The invention comprises a housing (1), an intermediate sleeve (2), a plunger (3) and a high-pressure gas source, wherein the intermediate sleeve (2) is fixed in the housing (1), an air inlet passage (51) is formed between the outer wall of the intermediate sleeve (2) and the inner wall of the housing (1), the upper end of the plunger (3) has a piston (31) rotatably connected to the inner wall of the intermediate sleeve (2), the middle part of the plunger (3) has an impeller (32), the plunger (3) and the intermediate sleeve (2) form a driving air cavity (52), the intermediate sleeve (2) has a plurality of air inlet holes (53) connecting the driving air cavity (52) and the air inlet passage (51), and the plunger (3) has an air flow passing through the upper end surface of the plunger (3). A reciprocating passage (54), the top of the intermediate sleeve (2) is fixedly connected to a cover plate (21) for sealing the upper opening of the intermediate sleeve (2), a pressurized air cavity (56) communicating with the reciprocating passage (54) is formed between the lower end surface of the cover plate (21) and the upper end surface of the plunger (3), a plurality of functional holes (55) communicating with the reciprocating passage (54) are provided in the middle of the plunger (3), the functional holes (55) being able to communicate with the outside world and the reciprocating passage (54) when the plunger (3) moves downward, and the functional holes (55) being able to communicate with the driving air cavity (52) and the reciprocating passage (54) when the plunger (3) moves upward; the lower end of the plunger (3) is provided with a micro-drill mounting head (33); The pressure-bearing surface of the plunger (3) in the pressure-bearing air cavity (56) is larger than the pressure-bearing surface of the plunger (3) in the driving air cavity (52); The diameter of the impeller (32) gradually decreases from top to bottom; The air inlet holes (53) are evenly distributed on the intermediate sleeve (2) in the circumferential direction, and an axis of the air inlet hole (53) forms an acute angle with a radial line of the intermediate sleeve (2).

2. According to claim 1, a micro drill driving head for PCB board processing, characterized in that: The impeller (32) comprises a plurality of flow-guiding convex ribs (321) uniformly arranged in the circumferential direction at the middle of the plunger (3); the flow-guiding convex ribs (321) are spiral-shaped.

3. A micro drill driving head for PCB board processing according to claim 1 or 2, characterized in that: The upper end of the shell has a connecting pipe (11) connected to the air inlet passage (51), and the high-pressure air source is directly or indirectly connected to the connecting pipe (11).

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