KR20030052501A - Air cylinder for press - Google Patents

Abstract

PURPOSE: An air cylinder for a press is provided to prevent damage of the coating surface of the lead frame by adjusting the speed of a piston, and to increase the productivity by quickly lifting the piston up and down. CONSTITUTION: An air cylinder comprises an upper housing(31) forming the large diameter internal space, and having a first air port(41) including an opening part opened in the large diameter space through a first air passage; a lower housing(32) extended to the lower part of the upper housing, and composed of the small diameter internal space, an opening part opened in the large diameter space through a second air passage and a second air port(43) connected to an opening part opened in the small diameter space through a third passage; a piston(33) reciprocating in the upper housing and the lower housing, and having the large diameter portion corresponding to the large diameter internal space and the small diameter portion corresponding to the small diameter internal space; and an air regulating unit installed in the second air passage to generate air flow resistance to the second air passage. The downward movement range of the piston is adjusted by adjusting the insertion position of the adjusting housing.

Description

Air cylinder for press {Air cylinder for press}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air cylinder for presses, and more particularly, to an air cylinder for presses that can be used for downset machining of lead frames.

In general, a semiconductor package using a lead frame, for example, a lead on chip used in the manufacture of a semiconductor package is subjected to downset processing. Downset processing is an operation of deforming the lead frame by pressing at least a portion of the lead frame to form the overall thickness of the semiconductor package as thin as possible. Alternatively, after the plating process is completed, a post treatment may be performed to press a portion of the inner lead to be wire bonded to form a step. At this time, the lead frame is deformed by being pressed by a mold mounted to the cylinder for pressing.

The mold mounted on the press cylinder is pressed to the surface of the lead frame to perform a predetermined downset process. At this time, since the lead frame is already plated in the pre-process, the surface of the mold and the plated surface of the lead frame are brought into contact with each other under pressure so that the plated surface may be damaged.

In practice, even if the plating surface is damaged by contact with the mold, no deterioration in the bonding property of the plating surface occurs. That is, the bonding property between the bonding wire and the plating surface of the lead frame is not much different from the case where the plating surface is not damaged. However, when the plated surface is damaged, an error process is often caused when the image of the wire bonding device is inspected and checked by the camera of the wire bonding device. Even though there is a lead, it is determined that there is no lead, and an error processing is performed. In the end, operation of the lead frame strip is no longer performed without wire bonding.

Damage to the plating surface of the lead frame is that the plating surface is impacted at a pressure of about 500 kg per square centimeter, so that the plating surface is partially broken and pressed, thereby causing a difference in surface roughness. To prevent this phenomenon, the speed of the mold should be adjusted to move the mold as slowly as possible. To this end, it is possible to adjust the mold speed by adopting a servo motor as the power for raising and lowering the mold and adjusting the speed of the servo motor. However, since the servo motor requires a long operation time, the overall productivity is greatly reduced.

On the other hand, when using a pneumatic cylinder to move the mold has the advantage that the overall productivity can be increased because the operating time is shortened, but there is a problem that can not adjust the moving speed of the mold in the pneumatic cylinder. That is, it has a constant speed over the entire stroke of the pneumatic cylinder, so that the piston rod of the pneumatic cylinder cannot be controlled as needed in the downset process.

1 is a schematic cross sectional view of a conventional press cylinder.

Referring to FIG. 1, the press air cylinder 10 includes a cylinder housing 11 and a piston 12 inserted into an inner space 13 of the cylinder housing 11. The piston rod 14 of the piston 12 extends out of the cylinder housing 11, with seals 15 and 16 respectively provided to maintain airtightness between the piston rod 14 and the cylinder housing 11. . On one side of the cylinder housing 11, the first air port 17 and the second air port 18 are formed at the upper and lower portions, respectively.

2 is a front view showing that the joint is coupled to the press air cylinder shown in FIG. Referring to the drawings, the joint 21 is mounted on the lower end of the piston rod 14. A mold, not shown, is connected to the piston rod 14 through the joint 21.

1 and 2, the press air cylinder 10 having the configuration as described in FIG. 2 is a piston (by the force of the pneumatic force supplied or blocked through the first air port 17 and the second air port 18) 12) this reciprocating motion. That is, when air is supplied through the first air port 17 and the air is discharged through the second air port 18, the piston 12 is lowered, while air is supplied through the second air port 18. When supplied and the air is discharged through the first air port 17, the piston 12 is raised.

In the operation of the air cylinder 10 as described above, it is impossible to control the raising and lowering speed of the piston 12. Therefore, it is impossible to prevent damage to the surface of the plating surface by slowing down the speed of the mold when pressing the plating surface of the lead frame. That is, when the piston 12 is close to the bottom dead center when the piston 12 descends, it must be able to reduce the falling speed of the piston 12 to reduce the impact force on the plated surface, but FIGS. 1 and 2 Such an operation is impossible with the air cylinder as shown in FIG.

In addition, in order to solve the above problems, a damper using an elastic body for reducing a separate impact may be provided, but the elastic body finally weakens the force applied to the lead, thereby making it difficult to achieve the desired purpose.

The present invention has been made to solve the above problems, an object of the present invention relates to an air cylinder for a press that can be prevented damage to the plated surface when pressed against the lead frame.

Another object of the present invention relates to an air cylinder for a press capable of speed control when the piston moves.

1 is a cross-sectional view of a conventional press air cylinder.

2 is a front view of a conventional press air cylinder.

3 is a schematic sectional view of a first embodiment of an air cylinder for a press according to the present invention;

Figure 4 is a front view of the air cylinder for press according to the present invention.

5 is a schematic cross-sectional view of a second embodiment of an air cylinder for a press according to the present invention.

6 is an enlarged cross sectional view of a portion of FIG. 5;

7 is a schematic perspective view of an adjustment housing.

<Brief Description of Major Codes in Drawings>

30. Cylinder 31. Cylinder upper housing

32. Cylinder lower housing 33. Piston

41. First air port 42. Cushion valve

43. Second air port 44. Connection flow path

In order to achieve the above object, according to the present invention, a large diameter inner space is formed, the upper housing having a first air port formed to have an opening opened in the large diameter inner space through the first air flow passage on the upper one side ; A second air port extending in a lower portion of the upper housing and having a small diameter internal space, the second air port having an opening opened in the large diameter internal space through a second air flow path, and connected to the second air port; A lower housing having a third air passage connected from the opening opened in the inner diameter space; A piston installed reciprocally in the upper housing and the lower housing, the piston having a large diameter portion corresponding to the large diameter inner space and a small diameter portion corresponding to the small diameter inner space; And a cushion valve installed in the second air flow path and having no flow resistance when supplying air to the large diameter internal space, and having a flow resistance when discharging air from the air cylinder. Is provided.

According to one feature of the invention, a connection flow path for connecting the second air flow path and the third air flow path is further formed.

According to another feature of the invention, from the moment the small diameter portion of the piston is inserted into the small diameter space of the lower housing, the resistance to the flow of air controlled through the cushion valve is generated, thereby increasing the speed of movement of the piston Slows down.

According to another feature of the invention, a large diameter inner space is formed, the upper housing having a first air port formed to have an opening opening in the large diameter inner space through the first air flow passage on the upper one side; A third air passage extending through a lower portion of the upper housing and having a cylindrical space formed therein, the second air port extending through a second air passage, and connected through an open opening of the small diameter inner space; A lower housing; It is installed to be movable in the cylindrical space inside the lower housing, a small diameter space is formed on the inside, the air inlet groove formed on the outer surface to correspond to the third flow path and extends therefrom and is open to the small diameter space An adjustment housing having an opening; A piston installed reciprocally in the upper housing and the adjustment housing, the piston having a large diameter portion corresponding to the large diameter inner space and a small diameter portion corresponding to the small diameter inner space; And a cushion valve installed in the second air flow path and having a flow resistance when the air is discharged.

According to another feature of the invention, the air inlet groove is formed as an annular space on the outer surface of the adjustment housing to have a width larger than the diameter of the third air flow path, so that the flow of air even if the adjustment housing is moved Can be done.

Hereinafter, the present invention will be described in more detail with reference to an embodiment shown in the accompanying drawings.

3 is a cross-sectional view of an air cylinder for a press according to the present invention.

Referring to the drawings, the air cylinder 30 includes an upper housing 31, a cylinder housing consisting of a lower housing 32, and a piston 33 inserted into the inner space of the cylinder housing to be reciprocated. A piston rod 34 is formed above and below the piston 33, and the piston rod 34 extends outside the upper housing 31 and the lower housing 32. Seals 37 and 38 are provided for airtightness between the piston rod 34 and the upper and lower housings 31 and 32, respectively.

The upper housing 31 defines a large diameter space 35 therein, and the lower housing 32 defines a small diameter space 36 inside. The large diameter space 35 and the small diameter space 36 are spaces extending upward and downward. On the other hand, the piston 33 also has a large diameter portion 33a and a small diameter portion 33b. The large diameter portion 33a of the piston 33 is formed to have a diameter corresponding to the large diameter space 35 of the upper housing 31, and the small diameter portion 33b of the piston 33 is the lower housing. It is formed to have a diameter corresponding to the small diameter space 36 of (32).

The first air port 41 is formed on one side of the upper end of the upper housing 31. The first air port 41 is opened to the large diameter space 35 through the first air flow passage 41a. Air supplied through the first air port 41 lowers the piston 33 downward. Air will also be exhausted through the first air port 41 when the piston 33 rises upwards.

The set screw 42 restricts the second air flow path 42a. That is, the inner end of the set screw 42 is formed in a conical shape, it is possible to limit the flow rate of the air flowing through the second air flow path (42a) in accordance with the degree of insertion into the second air flow path (42a). When the set screw 42 is deeply inserted into the second air flow passage 42a, the flow rate decreases, and conversely, when the set screw 42 is inserted shallowly, the flow rate increases. The second air passage 42a communicates with the second air port 43 through the connection passage 44.

The second air port 43 is formed at one side of the lower housing 32. The second air port 43 is opened to the inner surface of the large diameter space 35 through the connecting flow path 44 and the second air flow path 42a, and is also opened through the third air flow path 43a to the small diameter space. It is open to the inner surface of (36). The second air passage 42a and the third air passage 43a are connected to each other through the connection passage 44.

As shown in the figure, the small diameter space 36 is a closed space when the small diameter portion 33b of the piston 33 is closing the upper end of the small diameter space 36. Air supplied or discharged through the second air port 43 is supplied to or discharged from the small diameter space 36 through the third air flow passage 43a, and also the connection flow path 44 and the second air flow path ( 42a) is supplied or discharged to the large diameter space 35 below the large diameter portion 33a of the piston. A seal 39 is provided to maintain airtightness when the small diameter portion 33b of the piston 33 is inserted into the small diameter space 36.

4 is a front view showing that the joint is coupled to the air cylinder shown in FIG.

Referring to the drawings, the joint 44 is coupled to the lower end of the piston rod 34. A mold capable of downsetting the lead frame is mounted through the joint 44. The threaded upper end 49 of the joint 44 is screwed into the threaded hole formed in the piston rod 34, and the washer 48 is fitted to the threaded upper end 49.

The operation of the air cylinder described with reference to FIGS. 3 and 4 is as follows. When the piston 33 is raised, the air supplied through the second air port 43 is supplied to the large diameter space 35 and the small diameter space 36 defined at the lower portion of the piston 33. Here, the force for raising the piston until the bottom surface of the piston passes from the bottom dead center to the point where the seal 39 is provided is actually used to supply the small diameter space 36 through the third air passage 43a. Pressure. That is, since the conical end of the set screw 42 restricts the second air flow path 42a, the flow rate of the air supplied to the large diameter space 35 through the second air flow path 42a is relatively small, Therefore, the pressure by the air supplied to the large diameter space 35 is not so large. In addition, even after the bottom surface of the piston 33 passes through the seal 39, the supply of air through the third air flow path 43a is limited to the small diameter space 36 and the large diameter space 35 defined in the lower portion of the piston 33. ), The piston 33 rises smoothly. At this time, air is discharged through the first air port 41 along the first flow path 41a from the large diameter space 35 defined at the upper portion of the piston 33. Accordingly, the piston 33 can be raised quickly. In fact, when the piston 33 is raised, the air cylinder 30 shown in FIGS. 3 and 4 will raise the piston 33 at the same speed as the air cylinders of the prior art shown in FIGS. 1 and 2. Can be.

Next, when the piston 33, which is actually being worked down, the air flows into the large diameter space 35 defined above the piston 33 through the first air port 33, while the piston The air present in the large diameter space 35 and the small diameter space 36 defined at the lower portion of 33 must be discharged through the second air port 43. As described above, since the set screw 42 is installed in the second air flow path 42a, air flow resistance will be generated by the conical end portion which closes part of the flow path when the air is discharged. However, before the small diameter portion 33b of the piston 33 is inserted into the small diameter space 36, even though there is an air flow resistance in the second air passage 42a, most of the air passes through the third air passage. Piston 33 can be lowered quickly because it can be discharged through the second air port 43 through.

Once the small diameter portion 33b of the piston 33 is inserted into the small diameter space 36, the large diameter space 35 and the small diameter space 36 formed below the piston 33 are insulated from each other. do. Therefore, in order for the piston 33 to continue descending, the air present in the large diameter space 35 formed in the lower part of the piston 33 is the air at the conical end of the set screw 42 provided in the second air flow path 42a. Since it can only be discharged through flow resistance, its discharge flow rate is relatively very small. On the other hand, the air present in the small diameter space 36 can be smoothly discharged through the third air port 43. Therefore, since the flow resistance by the set screw provided in the 2nd air flow path 42a generate | occur | produces, the speed decreases as the piston 33 descends. That is, the combination of the two air flow paths 42a and 43a and the set screw 42 serves as a cushion valve to reduce the descending speed of the piston 33.

As described above, a small diameter space 36 is formed in the lower housing 32 and an air flow path provided with a set screw 42 which causes a flow resistance, and corresponds to the small diameter space 36 in the piston 33. The lowering speed of the piston 33 can be adjusted by forming the small diameter portion 33b. The discharge flow resistance of the air by the set screw 42 installed in the second air flow passage 42a starts to arise from the moment when the large diameter space 35 and the small diameter space 36 under the piston are mutually isolated. The instant coincides with the instant when the lower end of the small diameter portion 33b of the piston 33 begins to insert into the small diameter space 36.

5 is a cross-sectional view schematically showing a second embodiment of the press air cylinder according to the present invention. The second embodiment is to adjust the reach to the top of the object to be pressurized in the present invention, it is possible to further increase the productivity by increasing the section to be lowered quickly and the section to which the actual press is made short.

Referring to FIG. 5, the overall structure of the air cylinder 50 is similar to the first embodiment shown in FIG. 3, and the same parts are denoted by the same reference numerals. In addition, descriptions of components already described with reference to FIG. 3 will be omitted.

In the first embodiment shown in FIG. 3, the second air port 42 and the third air port 43 are formed on one side of the lower housing 32, while the second embodiment shown in FIG. 5 is formed. In the lower housing 32 'is further provided with an adjustment housing 51 formed to be adjustable, the second air port 43' is formed on one side of the lower housing (32 '). In addition, a second air flow passage 42a 'and a third air flow passage 43a' are formed, and are provided in the second air flow passage 42a 'and include a set screw 42' capable of generating flow resistance. do.

The adjusting housing 51 has a cylindrical shape that can be inserted into the cylindrical space formed by the lower housing 32 ', and has an opening in which the lower end of the piston rod 34 can be inserted. Seal 38 ′ is provided to maintain airtight between the piston rod 34 and the adjustment housing 51. In addition, the adjustment housing 51 is formed with a small diameter space 36 'into which the small diameter portion 33b of the piston 33 can be inserted. A seal 39 'is provided to maintain airtightness between the small diameter portion 33b and the small diameter space 36' of the adjustment housing 51.

The second air port 42 'is formed at one side of the lower housing 32', is opened to the large diameter space 35 through the second air flow passage 42a ', and the third air flow passage 43a'. Through small diameter space 36 '. As described with reference to the first embodiment of FIG. 3, a set screw 42 ′ for generating a flow resistance is provided in the second air flow path 42 a ′. On the other hand, the third air flow passage 43a 'is connected to the air flow passage of the adjustment housing 51, which will be described later in detail, and consequently opens to the small diameter space 36' of the adjustment housing 51. The second air passage 42a 'and the third air passage 43a' are connected to each other through the connection passage 44 '.

The adjusting housing 51 can move in the up and down direction with respect to the lower housing 32 ′. That is, the insertion depth can be adjusted by moving the adjustment housing 51 inward or outward of the lower housing 32 'according to the intention of the operator. This adjustment operation of the adjustment housing 51 is the moment when the small diameter part 33b of the piston 33 is inserted in the small diameter space 36 'of the adjustment housing 51 in the lowering of the piston 33. As shown in FIG. Will be decided. As described above, since the descending speed of the piston 33 can be reduced from the moment when the small diameter portion 33b of the piston 33 is inserted into the small diameter space 36 ', the small diameter space 36' is defined. The insertion depth adjustment of the adjustment housing 51 is to determine the moment when the descending speed of the piston 33 starts to slow down.

FIG. 6 is an enlarged cross-sectional view of a portion indicated by A in FIG. 5.

Referring to the drawings, the adjustment housing 51 is formed with an air passage 62 having an opening 63 that opens into the small diameter space 36 '. The air flow path 62 is connected to the air flow path 43 'formed in the lower housing 32'. The connection between the air passage 62 and the air passage 43a 'is formed through the air inlet groove 61. The air inflow groove 61 is an annular groove formed in the outer surface of the adjustment housing 51.

Shown in FIG. 7 is a schematic perspective view of the adjustment housing 51.

By referring to FIG. 7, the shape of the air inlet groove 61 may be understood. The outer opening of the air flow path 62 formed in the adjustment housing 51 is open to the surface of the air inlet groove 61.

As can be understood from FIG. 6 and FIG. 7, the upper and lower heights of the air inlet groove 61 are formed to be larger than the diameter of the opening of the third air flow path 43a 'opened to the inner surface of the lower housing 32'. . Therefore, even if the position of the air inlet groove 61 is changed by the adjustment housing 51 moving up and down with respect to the lower housing 32 ', the air inlet groove 61 with respect to the opening of the third air flow path 43a'. ) Is not disconnected. Air supplied or discharged through the third air flow path 43a 'of the lower housing 32' flows into or flows out of the air flow path 62 in which at least one is formed through the air inlet groove 61 of the adjustment housing 51. This air flow can be made without disconnection even if the lower housing 32 'is moved up and down because the air inlet groove 61 is widened up and down.

The action of the air cylinder 50 described with reference to FIGS. 5 to 7 is similar to the first cylinder 30 of FIG. 3. When the piston 33 rises, air flowing through the second air port 43 'flows into the small diameter space 36' without flow resistance through the third air flow path 43a ', and thereafter, When the bottom of the diameter portion 33b is raised above the position of the seal 39 ', the piston 33 can rise quickly by flowing into the large diameter space 35 again.

On the contrary, when the piston 33 is lowered, the lowering of the piston 33 is rapidly lowered until the small diameter portion 33b of the piston 33 is inserted into the small diameter space 36 'of the lower housing 32'. Is done. This is because the air in the large diameter space 35 and the small diameter space 36 'is smoothly flowed through the third air flow passage 43a' even if there is a flow resistance by the set screw 42 in the second air flow passage 42a '. Because it can be discharged. However, once the small diameter portion 33b of the piston 33 is inserted into the small diameter space 36 ', the air in the large diameter space 35 is transferred to the set screw 42 provided in the second air flow passage 42a'. The lowering of the piston 33 is subject to resistance because it can be discharged to the outside through the connecting flow path 44 'and the second port 43' only after passing through the air flow resistance. Accordingly, the lowering speed of the piston 33 is decelerated, and the mold (not shown) that is lowered by the movement of the piston 33 can press the plated surface of the lead frame at low speed. By adjusting the insertion depth of the adjustment housing 51 with respect to the lower housing 32 ', it is possible to adjust the moment at which the deceleration speed is reduced.

Press air cylinder according to the present invention can be lowered at a reduced speed over a predetermined period when the piston descends, there is an advantage that can perform a desired press action without damaging the plated surface of the lead frame. In addition, since the piston is raised and lowered rapidly, it may contribute to productivity improvement. Moreover, when the adjustment housing is provided, the lowering section of the piston can be adjusted according to the characteristics of the work by adjusting the insertion position of the adjustment housing.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is only illustrative, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. In particular, the air cylinder according to the present invention may be applied to operations other than the plated surface press of the lead frame. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (7)

An upper housing having a large diameter inner space, the upper housing having a first air port formed to have an opening opened in the large diameter inner space through a first air flow passage at an upper side thereof; Extends below the upper housing, a small diameter inner space is formed, and is connected to an opening opened in the large diameter inner space through a second air flow path and an opening opened in the small diameter inner space through a third flow path; A lower housing having a second air port formed therein; A piston installed reciprocally in the upper housing and the lower housing, the piston having a large diameter portion corresponding to the large diameter inner space and a small diameter portion corresponding to the small diameter inner space; And, And an air conditioner installed in the second air flow path to generate an air flow resistance to the second air flow path. The method of claim 1, The air cylinder for a press, characterized in that the connection passage further connecting the second air passage and the third air passage. The method of claim 1, From the moment when the small diameter portion of the piston is inserted into the small diameter space of the lower housing during the lowering of the piston, resistance to the flow of air discharged through the second air flow path is generated, thereby increasing the speed of movement of the piston. Air cylinder for press, characterized in that the deceleration. An upper housing having a large diameter inner space, the upper housing having a first air port formed to have an opening opened in the large diameter inner space through a first air flow passage at an upper side thereof; A cylindrical space extending in a lower portion of the upper housing and formed therein and connected to an opening opened in the large diameter space through a second air flow path and an opening opened in the small diameter internal space through a third air flow path; A lower housing having a second air port; It is installed to be movable in the cylindrical space inside the lower housing, a small diameter space is formed on the inside, the air inlet groove formed on the outer surface to correspond to the third flow path and extends therefrom and is open to the small diameter space An adjustment housing having an opening; A piston installed reciprocally in the upper housing and the adjustment housing, the piston having a large diameter portion corresponding to the large diameter inner space and a small diameter portion corresponding to the small diameter inner space; And, And an air conditioner installed in the second air flow path to generate an air flow resistance to the second air flow path. The method of claim 4, wherein The air inlet groove is formed on the outer surface of the adjustment housing to have a width larger than the diameter of the opening of the third air flow path, so that the air flow can be made even if the adjustment housing is moved. cylinder. The method of claim 4, wherein The air cylinder for a press, characterized in that the connection passage further connecting the second air passage and the third air passage. The method of claim 4, wherein From the moment the small diameter portion of the piston is inserted into the small diameter space of the lower housing, the resistance to the flow of air discharged through the cushion valve is generated, the movement speed of the piston is reduced for Air is loaded.