CN111970834A

CN111970834A - Stroke-adjustable micro-drill driving device

Info

Publication number: CN111970834A
Application number: CN202010958898.9A
Authority: CN
Inventors: 王波
Original assignee: Hubei University of Science and Technology
Current assignee: Hubei University of Science and Technology
Priority date: 2020-09-14
Filing date: 2020-09-14
Publication date: 2020-11-20

Abstract

The invention provides a micro-drill driving device with an adjustable stroke, and belongs to the technical field of precision machinery. The plunger is internally provided with an airflow reciprocating channel with the upper end penetrating through the upper end surface of the plunger, the top of the middle sleeve is fixedly connected with a cover plate for plugging an opening at the upper end of the middle sleeve, a pressurized air cavity communicated with the airflow reciprocating channel is formed between the lower end surface of the cover plate and the upper end surface of the plunger, and the middle of the plunger is provided with a plurality of functional holes communicated with the airflow reciprocating channel; the lower end of the plunger is provided with a micro-drill mounting head. The invention has the advantages of high operation efficiency and the like.

Description

Stroke-adjustable micro-drill driving device

Technical Field

The invention belongs to the technical field of precision machinery, and relates to a micro-drill driving device with an adjustable stroke.

Background

The PCB is also called a printed circuit board or a printed circuit board, and is an important electronic component, a support body of the electronic component, and a carrier for electrical connection, and along with the rapid development of highly integrated circuit boards, the PCB tends to be smaller, thinner and finer, a drill bit such as a micro screwdriver, a milling cutter and the like for processing the PCB, such as drilling, milling, and the like, tends to be finer, and a requirement for a driving mechanism for controlling the drill bit to rotate and stretch is higher and higher.

Particularly, the service life of the drill bit is seriously influenced by the problems of low strength, easy breakage, easy damage, easy deformation and the like of the drill bit due to the refinement of the drill bit; traditional drill bit actuating mechanism is the integration of many units control mechanism, the in-process occupation space who is applicable to automated production is big, it generally includes the rotary driving unit who orders about the rotation of little brill and the feed drive unit who controls the little brill and vertically feed/go out the sword, not only need coordinate the cooperation to two drive units among the automated production process, and in order to reduce the impact force of drill bit, the drill bit keeps certain rotation rate always, translation and the switching through vertical reciprocating motion cooperation PCB board realize the continuous processing of PCB board, the drill bit is in high fever all the time, high strength operation state, it is very big to the life influence of drill bit.

In addition, during the machining process, the drill bit directly contacts the PCB board at a relatively constant high rotation speed (the rotation speed is considered constant regardless of the change of the rotation speed when contacting the board) in either the feeding or the discharging, which causes the following problems: 1) the cutting heat is instantly generated to cause local thermal deformation on the PCB processing position; 2) the larger impact force can cause the increase of the positioning difficulty of the PCB and the dislocation of the PCB (especially the positioning strength of the micro PCB is not too high in the processing process); 3) the PCB is subjected to high-strength cutting due to no longitudinal buffer between the PCB and the drill, so that burrs/burrs at the edge of the opening or the slotting of the PCB are large, secondary repair deburring is usually needed, and the processing efficiency, the processing precision and the processing quality are negatively affected; 4) at the initial stage of feed, because the micro drill is not yet "eat the silk" with realizing between the panel, the micro drill tip resistance makes the axiality receive the negative surface influence, causes the emergence of the violent wearing and tearing of tool bit, tipping and disconnected sword condition easily, because of the existence of the anterior angle, relief angle, sharp angle and the helix angle of micro drill makes the micro drill receive the stress of deviating from the axis great, takes place the deformation of micro drill middle section easily, will greatly influence the life and the machining precision of micro drill after the axiality is influenced.

The heat dissipation is also an important factor for prolonging the service life of the micro drill, and the existing equipment for driving the micro drill to rotate does not have a means for effectively dissipating the heat of the micro drill.

Disclosure of Invention

The invention aims to provide a micro-drill driving device with adjustable stroke aiming at the problems in the prior art, and the technical problem to be solved by the invention is to realize the reciprocating stroke adjustment of a micro-drill driving head in a pneumatic mode.

The purpose of the invention can be realized by the following technical scheme: a micro drill driving device with adjustable stroke is characterized by comprising a shell, a middle sleeve, a plunger and a high-pressure air source, wherein the middle sleeve is fixed in the shell, an air inlet channel is formed between the outer wall of the middle sleeve and the inner wall of the shell, the upper end of the plunger is provided with a piston which is rotatably connected with the inner wall of the middle sleeve, the middle part of the plunger is provided with an impeller, an adjusting sleeve is connected between the lower end of the plunger and the middle sleeve, the adjusting sleeve is in threaded connection with the middle sleeve, the adjusting sleeve is in sliding connection with the plunger, a driving air cavity is formed between the upper end of the adjusting sleeve and the lower end of the piston, the middle sleeve is provided with a plurality of air inlets which are communicated with the driving air cavity and the air inlet channel, an air flow return channel with the upper end penetrating through the upper end face of the plunger is arranged in the plunger, the top of the middle sleeve is fixedly connected, a pressurized air cavity communicated with the airflow return channel is formed between the lower end face of the cover plate and the upper end face of the plunger, a plurality of functional holes communicated with the airflow return channel are formed in the middle of the plunger, the functional holes can be communicated with the outside and the airflow return channel when the plunger moves downwards, and the functional holes can be communicated with the driving air cavity and the airflow return channel when the plunger moves upwards; the lower end of the plunger is provided with a micro-drill mounting head.

Furthermore, the impeller includes that circumference evenly sets up a plurality of water conservancy diversion protruding muscle in the middle part of the plunger, the water conservancy diversion protruding muscle is the heliciform.

Further, the diameter of the impeller is gradually reduced from top to bottom.

Furthermore, each air inlet hole is circumferentially and uniformly distributed on the middle sleeve, and an acute angle is formed between the axis of each air inlet hole and the radial line of the middle sleeve.

Furthermore, the upper end of the shell is provided with a connecting pipe communicated with the air inlet channel, and the high-pressure air source is directly or indirectly connected with the connecting pipe.

Furthermore, the upper end face of the adjusting sleeve is provided with a limiting cushion pad made of rubber.

The working process is as follows:

the plunger piston moves upwards, and the micro drill rotates to discharge a cutter: at the moment, the function hole is communicated with the outside, the driving air cavity is separated from the pressurized air cavity, airflow passes through the high-pressure air source, the connecting pipe, the air inlet channel and the air inlet hole, when entering the driving air cavity from the air inlet hole, the high-pressure airflow acts on the impeller to enable the plunger to rotate, the volume of the driving air cavity is increased to enable the plunger to move upwards, and the plunger stops moving upwards when the function hole is communicated with the driving air cavity and overcomes the upward inertia force of the plunger. The working state corresponding to the micro drill is as follows: after finishing the processing such as tapping, the micro drill realizes the cutter by the action of slowly rotating and ascending until the micro drill is separated from the PCB.

The plunger is downwards moved, and the micro drill is rotationally fed: at the moment, the function hole is communicated with the driving air cavity and the pressed air cavity, airflow passes through the high-pressure air source, the connecting pipe, the air inlet channel, the air inlet hole, the driving air cavity, the function hole, the airflow reciprocating channel and the pressed air cavity, the pressed surface of the plunger in the pressed air cavity is larger than the pressed surface of the plunger in the driving air cavity, namely the pressed surface at the upper end of the plunger is the upper end surface of the piston, the pressed surface which is used for driving the plunger to move upwards and is the difference value between the section of the middle section of the plunger and the section of the piston, the plunger is enabled to move downwards under larger downward pressure of the pressed air cavity, the pressed air cavity expands greatly in the downward process of the plunger, the airflow is larger, the torque for the impeller and the plunger to rotate is larger when the function hole is communicated with the outside, the downward pressure of the plunger. The working state corresponding to the micro drill is as follows: the action of the micro drill descending at high speed and rotating limits the feeding of the micro drill, and the PCB is processed.

Exhausting: when the plunger moves downwards to the functional hole to be communicated with the outside, the pressure is released in the pressurized air cavity, and the airflow is discharged to the outside through the pressurized air cavity, the airflow reciprocating channel and the functional hole.

The plunger and the micro drill connected to the lower end of the plunger circulate the following working states: the cutter is rotated fast and moved downwards to perform feeding operation, and is rotated slowly and moved upwards to finish cutter discharging.

Because the impeller is in a conical shape with the diameter of the upper end larger than that of the lower end, in the descending process of the plunger, the gap between the impeller and the middle sleeve is gradually reduced, the stress surface of the impeller is gradually increased, and the airflow which does not participate in driving the impeller is gradually reduced, so that the rotating speed of the plunger is gradually increased, the PCB is processed from slow to fast so as to reduce the impact of the micro drill on the PCB, reduce the impact force between the cutter and the PCB before the micro drill enters the PCB, and greatly eliminate the cutter damage and rapid temperature rise caused by high-speed cutting; in the plunger ascending process, the clearance between the impeller and the middle sleeve is gradually increased, the stress surface of the impeller is gradually reduced, the airflow which does not participate in driving the impeller is gradually increased, the rotating torque of the plunger is gradually reduced, and the cutter discharging of the micro drill after the PCB is processed is realized from fast to slow.

The adjusting sleeve can change the position of the limiting cushion pad relative to the middle sleeve through rotation, so that the descending limit position of the plunger is changed, namely the time when the functional hole is communicated with the outside is changed, and the longitudinal reciprocating amplitude of the plunger is further adjusted; when breaking down, the plunger descends to extreme position, and the lower extreme of impeller and the contact of spacing blotter realize that the plunger descends and stops, and in the normal course of work, because begin to carry out the pressure release to the pressurized cavity when the plunger is descending to be close extreme position, the pressure that spacing blotter received also can not be very big, can realize spacing blotter and the exempting from of impeller contact through the position of adjusting atmospheric pressure and adjusting collar.

Because the driving head is in soft driving up and down and rotation, the impact force is small, the speed keeps continuous gradual change in the up and down running process of the plunger, the rotating speed also keeps gradual change matched with the work requirement, the working period of the plunger is greatly shortened, and the processing efficiency in the automatic processing process is further improved.

Compared with the existing micro-drill driving mode, the micro-drill driving head has the following advantages:

1. the shell is connected with the execution end of the machine tool or the mechanical arm, the connecting pipe is connected with the high-pressure air source, the power source (air pump) and the driving head can be arranged separately, the operation space of the driving head is greatly improved, the space occupation of the driving head is reduced, the bearing of the mechanical arm execution arm is reduced, the online structure of the automatic production line is simplified, and the multipoint synchronous processing with higher density can be realized by processing small-size PCB boards.

2. In response to the trend that the PCB is smaller and thinner, the driving head can realize high-frequency small-amplitude operation, and the small-amplitude operation means that the feeding distance required by processing a thin plate is small; the automatic production process can realize simultaneous operation of a plurality of machines on one plate.

3. The plunger and the micro drill connected to the plunger are not in rigid contact with the driving part in the whole working process, the probability of abrasion, heating, cutter breakage and the like of the micro drill can be reduced in the whole process soft contact mode, the service life of the cutter is prolonged, and the indirect performance of further improving the working efficiency is realized.

4. The driving head can be suitable for micro-drills with smaller diameters to be processed, and the weakening of the small-size micro-drill strength and the like still can not greatly influence the operation quality and the service life of the micro-drill due to smaller impact.

5. The driving head realizes high-frequency air cooling of the micro drill, reduces heat collection of the micro drill, and can eliminate the influence on the driving head caused by machining scraps by matching with a totally-enclosed structure of the driving head.

6. The lower end of the adjusting sleeve extends to the joint (contraction joint) of the micro-drill tool shank and the tool bit after the micro-drill is installed, so that air flow can cool the tool bit part along the surface of the micro-drill. In the installation process, the micro drill is installed firstly, and then the adjusting sleeve is installed.

Drawings

FIG. 1 is a schematic view of the structure of the driving head when a micro drill is installed.

Fig. 2 is a schematic structural diagram of the driving head when the plunger moves downwards (or upwards) until the functional hole is covered by the adjusting sleeve.

Fig. 3 is a schematic view of the present drive head as the plunger is lowered to an extreme position.

Fig. 4 is a schematic view of the present drive head as the plunger travels up to the limit position.

3 fig. 3 5 3 is 3 a 3 sectional 3 view 3 taken 3 along 3 a 3- 3 a 3 in 3 fig. 32 3. 3

In the figure, 1, a housing; 11. taking over a pipe; 2. a middle sleeve; 21. a cover plate; 3. a plunger; 31. A piston; 32. an impeller; 321. flow guiding convex ribs; 33. a micro-drill mounting head; 4. an adjusting sleeve; 41. a flow guide cavity; 42. an overflow channel; 43. a limiting buffer cushion; 51. an air intake passage; 52. a drive air cavity; 53. an air inlet; 54. an airflow shuttle channel; 55. a functional hole; 56. a pressurized air cavity; 6. and (5) micro-drilling.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

As shown in fig. 1 and 2, the driving head comprises a shell 1, a middle sleeve 2, a plunger 3 and a high-pressure air source, wherein the middle sleeve 2 is fixed in the shell 1, an air inlet channel 51 is formed between the outer wall of the middle sleeve 2 and the inner wall of the shell 1, a piston 31 which is rotatably connected with the inner wall of the middle sleeve 2 is arranged at the upper end of the plunger 3, an impeller 32 is arranged at the middle part of the plunger 3, an adjusting sleeve 4 is connected between the lower end of the plunger 3 and the middle sleeve 2, the adjusting sleeve 4 is in threaded connection with the middle sleeve 2, the adjusting sleeve 4 is in sliding connection with the plunger 3, a driving air cavity 52 is formed between the upper end of the adjusting sleeve 4 and the lower end of the piston 31, a plurality of air inlet holes 53 which are communicated with the driving air cavity 52 and the air inlet channel 51 are arranged on the middle sleeve 2, an air flow back-and-forth channel 54 is arranged in the plunger 3, the upper, a pressurized air cavity 56 communicated with the airflow reciprocating channel 54 is formed between the lower end face of the cover plate 21 and the upper end face of the plunger 3, a plurality of functional holes 55 communicated with the airflow reciprocating channel 54 are formed in the middle of the plunger 3, the functional holes 55 can be communicated with the outside and the airflow reciprocating channel 54 when the plunger 3 moves downwards, and the functional holes 55 can be communicated with the driving air cavity 52 and the airflow reciprocating channel 54 when the plunger 3 moves upwards; the plunger 3 has a microdriller attachment head 33 at its lower end.

As shown in fig. 5, the impeller 32 includes a plurality of flow guiding ribs 321 uniformly arranged in the middle of the plunger 3 in the circumferential direction, and the flow guiding ribs 321 are spiral. The diameter of the impeller 32 is gradually reduced from the top to the bottom. All the air inlet holes 53 are circumferentially and uniformly distributed on the middle sleeve 2, and an acute angle is formed between the axis of each air inlet hole 53 and the radial line of the middle sleeve 2.

A flow 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 flow guide cavity 41 and the outer wall of the plunger 3, and the flow guide cavity 41 is an annular cavity with the diameter gradually reduced from top to bottom.

The upper end of the shell is provided with a connecting pipe 11 communicated with the air inlet channel 51, and a high-pressure air source is directly or indirectly connected with the connecting pipe 11. The upper end surface of the adjusting sleeve 4 is provided with a limiting buffer cushion 43 made of rubber.

The working process is as follows:

the plunger 3 moves upwards, and the micro drill 6 rotates to discharge: at this time, the function hole 55 communicates with the diversion cavity 41 and the outside, the driving air cavity 52 is isolated from the pressurized air cavity 56, the air flow passes through the high-pressure air source, the connection pipe 11, the air inlet channel 51 and the air inlet hole 53, when entering the driving air cavity 52 from the air inlet hole 53, the high-pressure air flow acts on the impeller 32, the plunger 3 rotates, simultaneously, the volume of the driving air cavity 52 is increased, the plunger 3 moves upwards, and the plunger 3 stops moving upwards when the function hole 55 is communicated with the driving air cavity 52 and overcomes the upward inertia force of the plunger 3. The working state of the corresponding micro drill 6 is as follows: after finishing the processing such as drilling, the micro drill performs the action of slowly rotating and ascending until the micro drill is separated from the PCB, the middle process is shown as figure 2, and the limit position is shown as figure 4.

The plunger 3 descends, and the micro drill 6 rotates and feeds: at this time, the functional hole 55 communicates the driving air cavity 52 and the pressurized air cavity 56, the air flow passes through the high pressure air source, the adapter 11, the air inlet channel 51, the air inlet 53, the driving air cavity 52, the functional hole 55, the air flow back and forth channel 54 and the pressurized air cavity 56, because the pressurized surface of the plunger 3 in the pressurized air cavity 56 is larger than the pressurized surface of the plunger 3 in the driving air cavity 52, namely, the pressurized surface of the upper end of the plunger 3 is the upper end surface of the piston 31, and the pressurized surface of the middle part of the plunger 3 driving the plunger 3 to move upwards is the difference between the section of the middle part of the plunger 3 and the section of the piston 31, the plunger 3 moves downwards under the larger downward pressure of the pressurized air cavity 56, the pressurized air cavity 56 expands more in the downward movement process of the plunger 3, the air flow is larger, the torque for rotating the impeller 32 and the plunger 3 is larger when the air flow acts on, the pressure of the plunger 3 descending is instantaneously reduced to gradually stop descending. The working state corresponding to the micro drill is as follows: the action of the micro drill 6 descending at high speed and rotating limits the feeding of the micro drill to process the PCB, the middle process is shown as figure 2, and the limit position is shown as figure 3.

And (3) exhausting and cooling: when the plunger 3 moves downwards to the functional hole 55 to be communicated with the flow guide cavity 41, the pressure is released in the pressurized air cavity 56, air flow enters the flow guide cavity 41 from the pressurized air cavity 56, the air flow back and forth channel 54 and the functional hole 55 and is discharged from the overflow channel, and the air flow acts on the micro-drill tool shank from top to bottom to cool the tool shank and the tool bit below the tool shank. The overflow channel 42 can prolong the retraction interval after the plunger 3 descends, so that the micro drill 6 can ascend after the speed is reduced to be lower.

The plunger 3 and the micro drill connected to the lower end of the plunger 3 circulate the following working states: the cutter is rotated fast, moved downwards to perform feeding operation, rotated slowly and moved upwards to finish cutter discharging.

Because the impeller 32 is conical with the diameter of the upper end larger than that of the lower end, in the descending process of the plunger 3, the gap between the impeller 32 and the middle sleeve 2 is gradually reduced, the stress surface of the impeller 32 is gradually increased, and the airflow which does not participate in driving the impeller 32 is gradually reduced, so that the rotating speed of the plunger 3 is gradually increased, the PCB is processed at a slow speed to a fast speed, the impact of a micro drill on the PCB is reduced, the impact force between a cutter and the PCB before the micro drill enters the PCB is reduced, and the damage and the rapid temperature rise of the cutter caused by high-speed cutting can be greatly eliminated; in the upward process of the plunger 3, the clearance between the impeller 32 and the middle sleeve 2 is gradually increased, the stress surface of the impeller 32 is gradually reduced, and the airflow which does not participate in driving the impeller 32 is gradually increased, so that the rotating torque of the plunger 3 is gradually reduced, and the cutter discharging of the micro-drill after the PCB is processed is realized at the rotating speed from high speed to low speed.

The adjusting sleeve 4 can change the position of the limiting cushion 43 relative to the middle sleeve 2 through rotation, so that the descending limit position of the plunger 3 is changed, namely the time when the functional hole 55 is communicated with the flow guide cavity 41 is changed, and the longitudinal reciprocating amplitude of the plunger 3 is adjusted; when a fault occurs, the plunger 3 descends to the limit position, the lower end of the impeller 32 contacts with the limiting cushion 43 to realize the descending stop of the plunger 3, and in the normal working process, because the pressure relief of the pressure cavity is started when the plunger 3 descends to approach the limit position, the pressure received by the limiting cushion 43 cannot be large, and the contact-free of the limiting cushion 43 and the impeller 32 can be realized by adjusting the positions of the air pressure and the adjusting sleeve 4.

Because the driving head is in soft driving up and down and rotation, the impact force is small, the speed keeps continuous and gradual change in the up and down running process of the plunger 3, the rotating speed also keeps gradual change matched with the work requirement, the working period of the plunger 3 is greatly shortened, and the processing efficiency in the automatic processing process is further improved.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims

1. A micro drill driving device with adjustable stroke is characterized by comprising a shell (1), a middle sleeve (2), a plunger (3) and a high-pressure air source, wherein the middle sleeve (2) is fixed in the shell (1), an air inlet channel (51) is formed between the outer wall of the middle sleeve (2) and the inner wall of the shell (1), the upper end of the plunger (3) is provided with a piston (31) which is rotatably connected with the inner wall of the middle sleeve (2), the middle part of the plunger (3) is provided with an impeller (32), an adjusting sleeve (4) is connected between the lower end of the plunger (3) and the middle sleeve (2), the adjusting sleeve (4) is in threaded connection with the middle sleeve (2), the adjusting sleeve (4) is in sliding connection with the plunger (3), and 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 middle sleeve (2) is provided with a plurality of air inlets (53) which are communicated with the driving air cavity (52) and the air inlet channel (51), the plunger (3) is internally provided with an airflow back-and-forth channel (54) the upper end of which penetrates through the upper end surface of the plunger (3), the top of the middle sleeve (2) is fixedly connected with a cover plate (21) for plugging the opening at the upper end of the middle sleeve (2), a pressurized air cavity (56) communicated with an airflow back-and-forth channel (54) is formed between the lower end surface of the cover plate (21) and the upper end surface of the plunger (3), the middle part of the plunger (3) is provided with a plurality of functional holes (55) communicated with the airflow reciprocating channel (54), the functional hole (55) can be communicated with the outside and the airflow reciprocating channel (54) when the plunger (3) descends, the functional hole (55) can communicate the driving air cavity (52) with the air flow back-and-forth channel (54) when the plunger (3) moves upwards; the lower end of the plunger (3) is provided with a micro-drill mounting head (33).

2. The stroke-adjustable micro-drill driving device as claimed in claim 1, wherein the impeller (32) comprises a plurality of flow guiding ribs (321) uniformly arranged in the middle of the plunger (3) in the circumferential direction, and the flow guiding ribs (321) are helical.

3. A stroke adjustable micro-drill drive as claimed in claim 1 or 2, characterized in that the diameter of the impeller (32) is gradually reduced from top to bottom.

4. The micro drill driving device with adjustable stroke according to claim 1 or 2, characterized in that the air inlet holes (53) are evenly distributed on the middle sleeve (2) in the circumferential direction, and the axes of the air inlet holes (53) form an acute angle with the radial line of the middle sleeve (2).

5. The adjustable-stroke micro-drill driving device according to claim 1 or 2, wherein the upper end of the housing is provided with a connecting pipe (11) communicated with an air inlet channel (51), and the high-pressure air source is directly or indirectly connected with the connecting pipe (11).

6. A stroke-adjustable micro-drill driving device as claimed in claim 1 or 2, characterized in that the upper end surface of the adjusting sleeve (4) is provided with a limiting cushion pad (43) made of rubber.