WO2009035179A1

WO2009035179A1 - Bad hanger detecting and removal apparatus for curing machine

Info

Publication number: WO2009035179A1
Application number: PCT/KR2007/004475
Authority: WO
Inventors: Sung-Jin Beck
Original assignee: Minokorea Co., Ltd.
Priority date: 2007-09-11
Filing date: 2007-09-17
Publication date: 2009-03-19
Also published as: KR20090027090A; KR100918303B1

Abstract

A hanger type curing machine having a bad hanger detection unit is disclosed. The hanger type curing machine according to the present invention can periodically detect whether hangers (4) are defective, for example, whether clamp springs of the hangers to hold PCBs (2) to be cured are damaged or the hangers are distorted, using a clamp spring damage detection unit (800) or a distorted hanger detection unit (810) during a PCB curing process. Furthermore, if a bad hanger is detected, the curing machine can remove the bad hanger using a bad hanger removal unit (830) and feed a new normal hanger using a new hanger feed unit (850).

Description

BAD HANGER DETECTING AND REMOVAL APPARATUS

FOR CURING MACHINE

Technical Field

[1] The present invention relates, in general, to hanger type curing machines which cure

PCBs (printed circuit boards) using hangers throughout PCB holding, carrying and separating processes and, more particularly, to a hanger type curing machine having a bad hanger detection unit which can periodically detect whether hangers are defective, for example, whether springs of clamps to hold PCBs to be cured are damaged or the hangers are distorted, while conducting a PCB curing process, and in which if a bad hanger is detected, the bad hanger can be removed and replaced with a new normal hanger. Background Art

[2] Generally, PCBs (printed circuit boards) are widely used in various kinds of electronic or telecommunication products, such as mobile phones, computers, televisions, etc. Typically, circuit patterns are formed on the PCBs in such a way that a copper foil is attached on a thin substrate, a resist is printed on the copper foil into a predetermined pattern, and portions of the copper foil to which no resist is applied are removed using etching agent.

[3] Such a PCB requires several surface treatment processes to prevent an oxide film from being formed on the surface thereof, to remove foreign substances applied to the surface of the PCB during the manufacturing process and dry the PCB, or to rapidly cure coating material applied to the surface of the PCB. The present invention relates to a curing machine which cures PCBs while holding and carrying the PCBs. In this specification, although the present invention will be described while focusing on a curing machine, other surface treatment apparatuses including the curing machine, such as cleaning or drying apparatuses, also fall within the spirit and scope of the present invention.

[4] FIG. 1 is a view showing the construction of one example of a hanger type curing machine used in a process of manufacturing PCBs.

[5] As shown in the drawing, the curing machine 1 is constructed such that a plurality of hangers 4 circulates along conveyors 10 in a machine body 11. The conveyors 10 are horizontally installed in the machine body 11, in which a curing process (or a drying process) is performed, and are spaced apart from each other by a predetermined height.

[6] Furthermore, a PCB feeding unit 16 for feeding PCBs 2 is provided ahead of the machine body 11. A PCB discharge unit 17 is provided behind the machine body 11 to discharge the PCBs 2 to the outside of the machine body 11 after the PCBs 2 are separated from the corresponding hangers 4.

[7] Meanwhile, the machine body 11 has a rectangular tunnel shape which is open on the front and rear ends thereof. The conveyors 10 which are installed in the machine body 11 include a feed conveyor 13 which carries the hangers 4 rearwards, and a return conveyor 15 which carries the hangers 4 forwards. The feed conveyor 13 and the return conveyor 15 which are parallel to each other are respectively disposed at upper and lower predetermined positions. The feed conveyor 13 carries rearwards the hangers 4 that hold PCBs 2, and the return conveyor 15 carries forwards the hangers 4 from which the PCBs 2 are removed.

[8] FIG. 2 is a perspective view showing one hanger which is carried by the conveyors.

FIG. 2 illustrates the hanger having no PCB 2, and FIG. 3 illustrates the hanger which holds a PCB 2 thereon.

[9] As shown in the drawings, the hanger 4 includes two horizontal rods 42 and 43 which protrude to the left and right to enable the hanger 4 to be easily hung on the feed conveyor 13, a seating frame 45 which has a rectangular shape and supports the PCB 2 thereon, and a plurality of clamps 46 which are provided on the seating frame 45 to hold the periphery of the PCB 2. Here, two clamps 46 are provided on each of the upper, left and right ends of the seating frame 45, so that the upper, left and right ends of the PCB 2 are held by the corresponding clamps 46.

[10] Referring to FIG. 1, a hanger ascending device 20 and a hanger descending device 60 are respectively provided on the front and rear ends of the machine body 11 to enable the hangers 4 to sequentially circulate along the feed conveyor 13 and the return conveyor 15 which are spaced apart from each other by a predetermined distance.

[11] In detail, the hanger ascending device 20 is provided on the front end of the machine body 11 and functions to place upright each of the hangers 4 that are returned by the return conveyor 15 and lift and feed it to the feed conveyor 13. The hanger descending device 60 functions to move downwards each of the hangers 4 that are carried rearwards by the feed conveyor 13, and to feed it to the return conveyor 15 after orienting it in a horizontal direction.

[12] Furthermore, the hanger ascending device 20 is coupled to a PCB mounting device

30 which mounts PCBs 2 that are placed on the PCB feeding unit 16 to the hangers 4. The hanger descending device 60 is coupled to a PCB separation unit 70 which separates the PCBs 2 from the hangers 4 and transfers them to the PCB discharge unit 17.

[13] In other words, a hanger ascending and PCB mounting unit 40, which lifts the hangers 4 that are returned by the return conveyor 15 and mounts PCBs 2 to the hangers 4, and a hanger descending and PCB separation unit 50, which moves downwards the hangers 4 that are carried by the feed conveyor 13 and separates the PCBs 2 from the hangers 4, are respectively provided ahead of and behind the machine body 11.

[14] Thereby, the hangers 4 are sequentially circulated in the machine body 11 by the conveyors 10, the hanger ascending and PCB mounting unit 40 and the hanger descending and PCB separation unit 50. The PCBs 2 are processed through a curing process (or a drying or cleaning process) while they are carried along with the hangers 4.

[15] As such, in the hanger type curing machine, the hangers 4 conduct an important role in that they hold the PCBs and carry the PCBs rearwards. Therefore, the hangers 4 must reliably hold the PCBs 2 to prevent the PCBs 2 from being undesirably removed from the hangers 4. However, with the passage of time, there is a probability of removal of a PCB from the hanger 4 attributable to a reduction of the elasticity of the clamps of the hanger 4.

[16] FIG. 4 is an enlarged sectional view showing one of the clamps which are provided on the hanger to hold the PCB. As shown in the drawing, the clamps 46 are fastened to the seating frame 45 of the hanger and, preferably, they are fastened to a support plate 48 which is welded to the seating frame 45 and a support bar 44 which are spaced apart from each other by a predetermined distance.

[17] Each clamp 46 includes a rotating plate 465, a rotating shaft 463 and vertical plates

462. A clamp spring 467 is fitted over the rotating shaft 463, so that the rotating plate 465 is elastically biased by the clamp spring 467 in the direction in which the PCB 2 is compressed and held by the rotating plate 465. The rotating shaft 463 is provided through the two vertical plates 462 which are vertically fastened to the support plate 48. The rotating plate 465 integrally has, on a first end thereof based around the rotating shaft 463, a clamping part 469 for holding the perimeter of the PCB 2 and, on a second end thereof, a push part 468 which is brought into contact with and is compressed by a compression roller rod 703.

[18] Therefore, to mount the PCB 2 to the hanger 4 or to separate the PCB 2 from the hanger 4, a seating surface 470 of each seating frame 45 must be opened by rotating the push parts 468 of the rotating plates 465 around the rotating shafts 463 using external force, thus moving the clamping parts 469 away from the seating surface 470.

[19] As shown in FIG. 4, the compression roller rods 703 function to push the push parts

468 of the corresponding rotating plates 465 when mounting the PCB 2 to the hanger 4 or separating it therefrom. In detail, when each of the compression roller rods 703 is moved upwards by a predetermined height, the corresponding push part 468 is rotated around the rotating shaft 463, so that the clamping part 469 is moved away from the seating surface 470. Here, every time when the compression roller rods 703 push the corresponding clamps to mount the PCB 2 to the hanger 4 or separate it therefrom, the clamp springs 467 repeatedly undergo stress-strain. Therefore, with the passage of time, the elasticity of each clamp spring 467 deteriorates.

[20] If the elasticities of the clamp springs 467 excessively deteriorate, the PCB 2 may become undesirably removed and separated from the hanger 4 while it is carried by the feed conveyor 13. The conventional hanger type curing machine 1 has no means for preventing the PCB 2 from being arbitrarily dropped by the hanger 4. Thus, in the case of the conventional hanger type curing machine 1, events in which the operation of the machine is stopped by an accident of arbitrary removal of PCBs have frequently taken place.

[21] Therefore, the conventional hanger type curing machine 1 is problematic in that the productivity is reduced or the number of defective products is increased due to an accident of arbitrary removal of PCBs while the machine is being operated. Furthermore, to prevent arbitrary removal of PCBs, a worker must inspect the elasticity of every clamp spring before the machine is operated. If a bad hanger is detected, the replacement thereof must be performed by a manual method, with the result that the labor costs are increased. Disclosure of Invention Technical Problem

[22] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a hanger type curing machine having a clamp spring damage detection device which can automatically inspect whether clamp springs of hangers are damaged in such a way as to measure the elasticities of the clamp springs of each of the hangers, every time when a PCB is separated from each of the hangers which sequentially circulate in a curing machine body.

[23] Another object of the present invention is to provide a hanger type curing machine having a distorted hanger detection device which can automatically inspect whether each hanger is distorted in such a way as to measure whether upper and lower horizontal rods of the hanger that is carried by a return conveyor maintain the level state.

[24] A further object of the present invention is to provide a hanger type curing machine having a bad hanger removal unit which automatically removes, from the return conveyor, a hanger that is determined as a bad hanger by the clamp spring damage detection device and/or the distorted hanger detection device.

[25] Yet another object of the present invention is to provide a hanger type curing machine having a new hanger feed unit which automatically feeds a new normal hanger onto the return conveyor in place of the bad hanger removed by the bad hanger removal unit. Technical Solution

[26] In order to accomplish the above objects, the present invention provides a hanger type curing machine having a bad hanger detection unit, the curing machine including a plurality of hangers circulating along a conveyor, each of the plurality of hangers having a plurality of clamps to hold a PCB (printed circuit board), the bad hanger detection unit including a clamp spring damage detection unit, comprising: a hanger descending device to separate the hangers from the conveyor and orient the hangers in a horizontal direction; a plurality of compression roller rods provided to correspond to the respective clamps of each of the hangers; a main cylinder to move the compression roller rods to the respective clamps of the hanger to open the clamps; a load cell provided under a lower end of each of the compression roller rods, the load cell being compressed by the compression roller rod, thus measuring an elasticity of a clamp spring of the corresponding clamp; and a control unit electrically connected to the load cells, the control unit comparing the elasticity of each of the clamp springs measured by the load cells to a preset reference elasticity and determining the hanger as a bad hanger when the elasticity of the clamp spring of at least one clamp is less than the reference elasticity, and outputting a control signal indicating the determination result, whereby the clamp spring damage detection unit detects whether each of the clamp springs of the hanger is damaged, every time when the PCB is separated from the corresponding hanger.

[27] In order to accomplish the above objects, the present invention provides a hanger type curing machine having a bad hanger detection unit, the curing machine including a plurality of hangers, each of which has two horizontal rods to hold a PCB having a predetermined size, the hangers being returned by a return conveyor in a horizontally oriented state, the bad hanger detection unit including a distorted hanger detection unit, comprising: a plurality of distance measurement sensors provided above the return conveyor at predetermined heights at positions corresponding to opposite ends of the horizontal rods of each of the hangers that are returned by the return conveyor; a stopper unit to stop each of the hangers that are returned by the return conveyor at a constant position; a hanger lift device to lift the hanger that is stopped by the stopper unit to a predetermined height such that the horizontal rods of the hanger come into contact with the corresponding distance measurement sensors; and a control unit electrically connected to the distance measurement sensors, the control unit determining the hanger as a distorted hanger when a difference in distances or pressures measured by the distance measurement sensors is beyond a predetermined limit, and outputting a control signal indicating the determination result, whereby the distorted hanger detection unit detects whether the hanger is distorted, every time when the hanger is returned along the return conveyor. [28] In order to accomplish the above objects, the present invention provides a hanger type curing machine having a bad hanger detection unit, the curing machine including: a plurality of hangers, each of which has a plurality of clamps to hold a PCB; a feed conveyor to carry the hangers holding the PCBs rearwards while the hangers are hung on the feed conveyor in a vertically oriented state; a return conveyor provided below the feed conveyor at a position spaced apart from the feed conveyor by a predetermined distance, the return conveyor returning each of the hangers forwards in a horizontally oriented state after the PCB is separated from the hanger; a machine body having the feed conveyor and the return conveyor therein; a hanger ascending and PCB mounting unit provided ahead of the machine body, the hanger ascending and PCB mounting unit moving upwards each of the hangers that are returned and placing the hanger upright, and hanging the hanger on the feed conveyor after mounting a subsequent PCB to the hanger; and a hanger descending and PCB separating unit provided behind the machine body, the hanger descending and PCB separating unit moving downwards each of the hangers that are carried rearwards and orienting the hanger in a horizontal direction, and placing the hanger onto the return conveyor after separating the PCB from the hanger, wherein the bad hanger detection unit comprises: a clamp spring damage detection unit comprising a hanger descending device to hold each of the hangers that are carried rearwards by the feed conveyor and move the hanger downwards, and orient the hanger such that the hanger is parallel to a ground and the clamps of the hanger face the ground, a plurality of compression roller rods provided to correspond to the respective clamps of the hanger that is held by the hanger descending device, a main cylinder to move the compression roller rods to the respective clamps of the hanger to open the clamps, a load cell provided under a lower end of each of the compression roller rods, the load cell being compressed by the compression roller rod, thus measuring an elasticity of a clamp spring of the corresponding clamp, and a control unit electrically connected to the load cells, the control unit comparing an elasticity of each of the clamp springs measured by the load cells to a preset reference elasticity and determining that the hanger is a bad hanger when the elasticity of at least one clamp spring is less than the reference elasticity, and outputting a control signal indicating the determination result; and a distorted hanger detection unit comprising a plurality of distance measurement sensors provided above the return conveyor at predetermined heights at positions corresponding to opposite ends of horizontal rods of each of the hangers that are returned by the return conveyor, a stopper unit to stop each of the hangers that are returned by the return conveyor at a constant position, a hanger lift device to lift the hanger that is stopped by the stopper unit to a predetermined height such that the horizontal rods of the hanger come into contact with the corresponding distance measurement sensors, and a control unit electrically connected to the distance measurement sensors, the control unit determining the hanger as a distorted hanger when a difference in distances or pressures measured by the distance measurement sensors is beyond a predetermined limit, and outputting a control signal indicating the determination result, whereby the bad hanger detection unit detects whether each of the clamp springs of the hanger is damaged, every time when the PCB is separated from each of the hangers, and detects whether the hanger is distorted every time when the hanger is returned along the return conveyor.

[29] Preferably, each of the hangers may include: a seating frame provided at a central position between the upper and lower horizontal rods, the seating frame having a rectangular shape and supporting a periphery of the PCB; and the plurality of clamps integrally provided on the seating frame to hold the periphery of the PCB.

[30] Furthermore, each of the clamps may include: a rotating plate provided so as to be rotatable around a rotating shaft; and the clamp spring fitted over the rotating shaft to apply elastic force to the rotating plate in a direction in which the rotating plate holds the PCB.

[31] The clamp spring damage detection unit may further comprise a seating frame holding device to hold the seating frame or a support bar provided with the clamps, before the compression roller rods compress the respective clamps, wherein the seating frame holding device may include: a plurality of holders respectively having holding depressions on ends thereof to hold or release the seating frame or the support bar using horizontal movement of the holders; a horizontal cylinder to actuate the holders in the horizontal directions; a support frame supporting the horizontal cylinder and the holders thereon; and a vertical cylinder to actuate the support frame upwards or downwards.

[32] In addition, each of the compression roller rods may include: a movable part, having two vertical sidewalls integrally provided at positions spaced apart from each other by a predetermined distance, and a support shaft provided between the vertical sidewalls in a horizontal direction, with at least one rotating roller provided on the support shaft so as to be rotatable; and a stationary part, having a guide depression to guide vertical movement of the movable part, and a seating depression supporting the load cell therein such that the load cell comes into contact with the movable part and is operated in conjunction with the movable part.

[33] The stopper unit of the distorted hanger detection unit may include: at least one detecting sensor to sense positions of the hangers that are returned by the return conveyor and decelerate or stop the return conveyor; a stopper to stop each of the hangers at the constant position in such a way as to protrude from the return conveyor upwards; and a cylinder to actuate the stopper upwards or downwards depending on a control signal of the detecting sensor.

[34] The hanger lift device of the distorted hanger detection unit may include: two arms having V-shaped notches, into which the horizontal rods of each of the hangers that are returned by the return conveyor are seated; a drive unit including a motor to move the two arms upwards or downwards, and a belt and a pulley to convert rotating motion of the motor into vertical linear motion; a slide block connected to the belt to move the two arms upwards or downwards; and at least one guide rod to guide the vertical movement of the two arms.

[35] The control unit of the clamp spring damage detection unit and the control unit of the distorted hanger detection unit may be integrated into a single control unit.

[36] The control unit may include: a reception unit to receive electrical signals from the load cells or the distance measurement sensors; a main processor to convert the electrical signals input from the load cells or the distance measurement sensors into elasticity values or distance values or compare the electrical signals to the preset reference elasticity pressure value, and determine whether each of the hangers is a bad hanger; a transmission unit to transmit a control signal output from the main processor to an outside; an input unit to input reference value data, a memory unit to store the data input by the input unit; and a power supply unit to supply power.

[37] The hanger type curing machine may further include a bad hanger removal unit, comprising: a first slider provided above the return conveyor at a position spaced apart from the return conveyor by a predetermined height; a first guide rail to guide the first slider such that the first slider is horizontally movable in a direction perpendicular to a direction in which the return conveyor moves the hangers; a plurality of first hanger clampers provided under a lower surface of the first slider to hold the upper and lower horizontal rods of one bad hanger selected from among the hangers that are moved by the return conveyor; a plurality of first vertical cylinders provided in the first slider to move the first hanger clampers upwards or downwards; and a first drive unit to control the horizontal movement of the first slider and the actuation of the first hanger clampers and the first vertical cylinders depending on a control signal of the clamp spring damage detection device, whereby the bad hanger removal unit removes the bad hanger having a damaged clamp spring from the return conveyor.

[38] Furthermore, the hanger type curing machine may further comprise a new hanger feed unit to feed a new hanger onto the return conveyor in place of the bad hanger that is removed by the bad hanger removal unit. Advantageous Effects

[39] A hanger type curing machine according to the present invention can automatically inspect whether clamp springs of hangers are damaged in such a way as to measure the elasticities of the clamp springs of each hanger, every time when a PCB is separated from each of the hangers which sequentially circulate in a curing machine body.

[40] Furthermore, the curing machine of the present invention can automatically inspect whether each hanger is distorted in such a way as to measure whether upper and lower horizontal rods of each of the hangers that circulate in the curing machine body maintain the level state while the hanger is carried by a return conveyor.

[41] In addition, the curing machine of the present invention can automatically remove a hanger that is determined as a bad hanger from the return conveyor and replace the bad hanger with a new normal hanger, while the hangers are being carried by the return conveyor.

[42] Moreover, the present invention continuously performs the operation of detecting and removing a hanger which is determined as a bad hanger due to damage of clamp springs or distortion of horizontal rods, thus preventing a PCB from being undesirably dropped by the hanger during a curing process. Hence, the curing machine of the present invention can enhance the productivity thereof, reduce the number of defective products, and reduce labor consumption, thereby preventing an increase of the cost of producing PCBs.

[43] As well, in the present invention, even if a bad hanger occurs while the curing machine is operated, because the bad hanger can be automatically detected and removed, an accident of arbitrary removal of a PCB is prevented when the curing machine is in operation. Therefore, the present invention can markedly reduce the number of defective PCBs attributable to the accidental removal of the PCB. Furthermore, the present invention can automatically perform the operation of detecting and removing a bad hanger and the operation of replacing it with a new one, thus reducing labor consumption. Brief Description of Drawings

[44] FIG. 1 is a view showing the construction of a typical hanger type curing machine used in a process of manufacturing PCBs;

[45] FIGS. 2 and 3 are perspective views showing a hanger used in the typical hanger type curing machine;

[46] FIG. 4 is an enlarged side view showing a clamp for clamping a PCB;

[47] FIG. 5 is a side view illustrating a curing machine having a bad hanger detection unit, according to the present invention;

[48] FIG. 6 is a side view illustrating a hanger ascending and PCB mounting unit according to the present invention; [49] FIG. 7 is a side view illustrating a hanger descending and PCB separating unit according to the present invention; [50] FIG. 8 is a schematic perspective view illustrating a machine body and a conveyor unit according to the present invention; [51] FIG. 9 is a schematic plan view illustrating a clamp spring damage detection unit, a distorted hanger detection unit, a bad hanger removal unit and a new hanger feed unit according to the present invention;

[52] FIG. 10 is a block diagram showing the construction of a control unit of FIG. 9;

[53] FIGS. 11, 12 and 13 respectively are a plan view, a front view and a side view showing the construction of the clamp spring damage detection unit according to the present invention; [54] FIG. 14 is an enlarged side view showing the construction of the clamp spring damage detection unit and compression roller rods according to the present invention; [55] FIG. 15 is a schematic side view showing one example of the distorted hanger detection unit according to the present invention; [56] FIGS. 16, 17 and 18 respectively are a plan view, a front view and a side view showing another example of the distorted hanger detection unit according to the present invention; and [57] FIG. 19 is a schematic side view illustrating the bad hanger removal unit and the new hanger feed unit according to the present invention. [58] ***Description of the elements in the drawings***

[59] 2: PCB 4: hanger

[60] 42, 43: horizontal rod 110: conveyor unit

[61] 111: machine body 116: PCB feeding unit

[62] 117: PCB discharge unit 130: feed conveyor

[63] 150: return conveyor 200: hanger ascending device

[64] 250: hanger feed cylinder 300: PCB mounting device

[65] 400: hanger ascending and PCB mounting unit 467: clamp spring

[66] 500: hanger descending and PCB separation unit

[67] 600: hanger descending device

[68] 650: hanger drawing device 700: PCB separation unit

[69] 703: compression roller rods 706: main cylinder

[70] 720: seating frame holding device 721: holder

[71] 800: clamp spring damage detection unit 801: load cell

[72] 802: control unit 811: distance measurement sensor

[73] 820: hanger lift device 828: arm

[74] 850: stopper unit 830: bad hanger removal unit [75] 850: new hanger feed unit

Best Mode for Carrying out the Invention

[76] Hereinafter, a curing machine having a bad hanger detection unit according to the present invention will be described in detail with reference to the attached drawings.

[77] FIG. 5 is a side view illustrating the curing machine having the bad hanger detection unit, according to the present invention.

[78] Referring to FIG. 5, the curing machine 100 having the bad hanger detection unit according to the present invention (hereinafter, referred to as 'curing machine') includes a machine body 111, a PCB feeding unit 116 and a PCB discharge unit 117.

[79] Furthermore, a conveyor unit 110 is provided in the machine body 111. The conveyor unit 110 includes a feed conveyor 130 which moves hangers 4 rearwards, and a return conveyor 150 which returns forwards the hangers 4 that have been moved rearwards. The feed conveyor 130 and the return conveyor 150 are provided parallel to each other at positions spaced apart from each other in a vertical direction by a predetermined distance.

[80] In addition, a hanger ascending and PCB mounting unit 400 is provided on the front end of the machine body 111, that is, between the machine body 111 and the PCB feeding unit 116. The hanger ascending and PCB mounting unit 400 raises each hanger 4 which has been returned forwards and mounts a corresponding PCB 2 to the front surface of the hanger 4. A hanger descending and PCB separation unit 500 is provided on the rear end of the machine body 111, that is, between the machine body 111 and the PCB discharge unit 117. The hanger descending and PCB separation unit 500 moves downwards each of the hangers 4 which have been moved rearwards and separates the corresponding PCB 2 from the front surface of the hanger 4.

[81] Moreover, a clamp spring damage detection unit 800 is installed below the hanger descending and PCB separation unit 500, specifically, below a PCB separation device 700. The clamp spring damage detection unit 800 measures the elasticity of clamp springs using load cells when separating a PCB from the corresponding hanger 4, compares it to a reference elasticity, and determines whether the hanger 4 is a bad hanger.

[82] A distorted hanger detection unit 810, a bad hanger removal unit 830 and a new hanger feed unit 850 are installed in the machine body 111, specifically, around the return conveyor 150, and are disposed at positions spaced apart from each other at regular intervals.

[83] The construction of the curing machine will be explained in more detail with reference to the attached drawings.

[84] As shown in FIGS. 5 and 6, the PCB feeding unit 116 is installed ahead of the machine body 111 and has a plurality of rollers 118 for carrying PCBs 2. The PCB feeding unit 116 functions to feed PCBs, which have been carried from another curing machine or printer (not shown), into the machine body 111.

[85] Referring to FIGS. 5 and 7, the PCB discharge unit 117 is installed behind the machine body 111 and has a conveyor belt 119 for horizontally carrying the PCBs 2. The PCB discharge unit 117 functions to feed the PCBs to another curing machine or printer.

[86] Referring to FIGS. 5 and 8, the machine body 111 includes a main body casing 112 which has a rectangular tunnel shape, and a conveyor unit 110 which is installed in the main body casing 112 and circulates the hangers 4.

[87] The main body casing 112 has a rectangular tunnel shape which is open on front and rear ends thereof such that the PCBs 2, each of which has a predetermined size and is in an upright state, can move through the main body casing 112. Apparatuses (not shown) required for curing PCBs 2 are installed in the main body casing 112. The PCBs 2 are held by the corresponding hangers 4 and carried along the conveyor unit 110 while they are cured.

[88] As shown in FIG. 8, the feed conveyor 130 is constructed such that several hangers 4 can be carried in upright states. For example, the feed conveyor 130 includes two plate-shaped conveyors 131, which are oriented parallel to each other and are spaced apart from each other by a predetermined distance. Each plate-shaped conveyor 131 comprises two plates 132 and 133 which are disposed adjacent to each other. Hanging depressions 134, on one of which an upper horizontal rod 42 of each hanger 4 is seated, are formed in each plate 132, 133 at positions spaced apart from each other at regular intervals. Therefore, the horizontal rod 42 which has been hung on one hanging depression 134 is consecutively moved to the following hanging depression 134 by alternately actuating the plates 132 and 133 upwards, downwards, forwards and rearwards using a drive unit (not shown).

[89] The return conveyor 150 is constructed such that the hangers 4 from which the PCBs

2 are removed can be returned in horizontally placed states. For example, the return conveyor 150 comprises two conveyor belts 151 and 152 which are spaced apart from each other by a predetermined distance. It is preferable that the conveyor belts 151 and 152 be spaced apart from each other by a predetermined distance such that the opposite ends of horizontal rods 42 and 43 of each hanger 4 protrude outwards from the conveyor belts 151 and 152. Therefore, when the return conveyor 150 is rotated, the hangers 4 placed thereon are carried in the direction in which the return conveyor 150 is rotated.

[90] Referring to FIGS. 5 and 6, the hanger ascending and PCB mounting unit 400 is installed in the front end of the machine body 111 and includes a hanger ascending device 200 and a PCB mounting device 300. The hanger ascending device 200 raises each of the hangers 4 which have been returned by the return conveyor 150 and supports the hanger 4 after orienting it in the vertical direction. The PCB mounting device 300 holds, by suction, a PCB 2 which is placed on the PCB feeding unit 116, rotates the PCB 2, and mounts it to the corresponding hanger 4, which is supported by the hanger ascending device 200 in the upright state. Furthermore, the hanger ascending and PCB mounting unit 400 further includes a hanger feed cylinder 250 which moves the hanger 4 that holds the PCB 2 rearwards and hangs it on the corresponding hanging depressions 134 of the feed conveyor 130.

[91] As shown in FIGS. 5 and 7, the hanger descending and PCB separation unit 500 is installed in the rear end of the machine body 111 and includes a hanger descending device 600 and a PCB separation device 700. The hanger descending device 600 moves each of the hangers 4 that are carried in the upright states by the feed conveyor 130 downwards and orients the hanger 4 in the horizontal direction. The PCB separation device 700 pushes clamps 46 of the hanger 4 and thus separates the PCB 2 from the hanger descending device 600.

[92] Furthermore, a hanger drawing device 650 is further provided between the feed conveyor 130 and the hanger descending device 600. The hanger drawing device 650 draws each of the hangers 4 from the feed conveyor 130 and supplies it to the hanger descending device 600 one by one. In addition, a hanger transfer device (not shown) may be provided between the PCB separation device 700 and the return conveyor 150. The hanger transfer device transfers each hanger 4 which is separated from the PCB separation device 700 to the return conveyor 150.

[93] Next, the clamp spring damage detection unit 800, the distorted hanger detection unit

810, the bad hanger removal unit 830 and the new hanger feed unit 850 will be explained with reference to FIGS. 5, 9 and 10.

[94] FIG. 9 is a view schematically showing the clamp spring damage detection unit 800, which is provided on the PCB separation device 700, and showing the distorted hanger detection unit 810, the bad hanger removal unit 830 and the new hanger feed unit 850 which are arranged along the return conveyor 150.

[95] As shown in the drawing, the clamp spring damage detection unit 800 includes a plurality of load cells 801 which are provided under respective compression roller rods 703 and measure the elasticities of the corresponding clamp springs in conjunction with the compression roller rods 703, and a control unit 802 which determines whether the corresponding hanger 4 is bad using pressures measured by the load cells 801.

[96] The distorted hanger detection unit 810 includes a plurality of distance measurement sensors 811 which are provided above the return conveyor 150 and measure whether the horizontal rods 42 and 43 of each of the hangers 4 which are carried by the return conveyor 150 are horizontally oriented or are parallel to each other. The distorted hanger detection unit 810 further includes the control unit 802 which determines whether the horizontal rod 42 or 43 is distorted in such a way as to compare pressure values measured by the distance measurement sensors 811 to the reference value.

[97] Each of the bad hanger removal unit 830 and the new hanger feed unit 850 includes a slider 831, 851 which perpendicularly moves the hanger 4 that is placed on the return conveyor 150, and guide rails 833, 853 which guides the slider 831, 851. Each of the bad hanger removal unit 830 and the new hanger feed unit 850 further include hanger clampers 835, 855 which are provided under the slider 831, 851 and hold the hanger 4, and a drive unit 834, 854 which moves the slider 831, 851.

[98] In addition, at least two position sensors 809 and 839 are provided around the return conveyor 150 to sense the position of the hanger 4. The position sensors 809 and 839 reduce the velocity of the return conveyor 150 or operate a stopper which will be described later.

[99] Meanwhile, preferably, the control unit 802 which detects a bad hanger and the control unit 802 which detects distortion of the horizontal rods may be integrated into a single control unit 802. Furthermore, the control unit 802 controls the drive units 834 and 854 of the bad hanger removal unit 830 and the new hanger feed unit 850.

[100] Next, the curing machine having the bad hanger detection unit according to the present invention will be described in more detail with reference to the attached drawings.

[101] As shown in FIGS. 5 and 6, the hanger ascending device 200 according to the present invention includes an ascending head 203 which moves upwards or downwards, and a hanger clamper 205 which is provided on the ascending head 203 and removably holds the upper horizontal rod 42 of one hanger 4. The hanger ascending device 200 further includes a guide rail 201 which is inclined at a predetermined angle to guide the operation of raising the hanger 4, and a drive unit 204 which actuates the ascending head 203. The ascending head 202 having the above-mentioned construction holds and raises each of the hangers 4 which are transferred from the return conveyor 150 and, simultaneously, places it upright.

[102] The PCB mounting device 300 includes a rotating unit 301 which is provided above the PCB feeding unit 116, and a cylinder rod 303 which is connected to the rotating unit 301. The PCB mounting device 300 further includes a rotating head 305 which is provided on the front end of the cylinder rod 303 and is rotated forwards or rearwards by the rotating unit 301, and a plurality of suction plates 307 which are provided on the rotating head 305 and removably hold, by suction, one PCB 2 which is placed on the PCB feeding unit 116. Hence, the rotating head 305 holds the PCB 2 by suction and is thereafter rotated by the rotation of the rotating unit 301 such that the PCB 2 faces the corresponding hanger 4.

[103] Here, horizontal compression roller rods 309 are provided ahead of the hanger 4 that is placed upright by the ascending head 203, and they are disposed at positions corresponding to the respective clamps 46 of the hanger 4. In addition, a support unit is provided behind of the hanger 4 that is placed upright to maintain the upright state of the hanger 4. Furthermore, the PCB mounting device 300 further includes a cylinder (not shown) which moves the horizontal compression roller rods 309 rearwards by a predetermined distance.

[104] When the horizontal compression roller rods 309 compress the respective clamps 46 of the hanger 4 after the PCB 2 that is held by the PCB mounting device 300 faces the hanger 4, the clamps 46 are opened, in other words, a seating surface of the hanger 4 is opened. Thereafter, the cylinder rod 303 is extended so that the PCB 2 is seated onto a seating frame 45 of the hanger 4. Subsequently, the horizontal compression roller rods 309 are contracted. Then, clamping parts of the clamps 46 hold the PCB 2. Thereafter, the suction plates 307 are removed from the PCB 2 and the cylinder rod 303 is contracted. The rotating head 305 is subsequently rotated and returned to its original position. The hanger 4 that holds the PCB 2 is hung on the corresponding hanging depressions of the feed conveyor 130 by the hanger feed cylinder 250.

[105] Meanwhile, as shown in FIGS. 5 and 7, the hanger drawing device 650 includes a drawing head 651 which is provided on the upper portion of the rear end of the feed conveyor 130, a hanger clamper 653 which is provided under the lower end of the drawing head 651 and holds the upper horizontal rod 42 of the corresponding hanger 4, and a drawing cylinder 656 which moves the drawing head 651 forwards or rearwards.

[106] The hanger descending device 600 includes a guide rail 601 which has an inclined surface thereon, a rectangular descending head 602 which moves upwards or downwards along the guide rail 601, and a hanger clamper 657 which is provided on the descending head 602 and holds the upper horizontal rod 42 of the hanger 4 that is drawn out by the hanger drawing device 650. The hanger descending device 600 further includes hanger holding rods 658 which hold the left and right edges of the hanger 4, and a drive unit 659 which actuates the descending head 602 such that it moves along the guide rail 601.

[107] Therefore, the descending head 602 moves downwards after holding the hanger 4 that is drawn out by the hanger drawing device 650. Thereafter, the descending head 602 is guided by the inclined surface of the guide rail 601 and is oriented in the horizontal direction such that the descending head 602 is parallel to the bottom surface of the machine.

[108] The PCB separation device 700 is installed such that it corresponds to the lower surface of the descending head 602 that is placed in the horizontal direction by the hanger descending device 600. The PCB separation device 700 includes a plurality of compression roller rods 703 which are oriented in vertical directions and are disposed at positions corresponding to the clamps 46 of the hanger 4 that is held by the descending head 602 in the horizontal state, and rod supports 704 to which the compression roller rods 703 are mounted. The PCB separation device 700 further includes main cylinders 706 which move the respective rod supports 704 upwards or downwards, and a seating frame holding device 720 which holds the seating frame 45 or a support bar 44 of the hanger 4 to prevent the hanger 4 from being undesirably bent.

[109] Thus, when the descending head 602 moves downwards, the clamps 46 of the hanger 4 enter a state in which they face the respective compression roller rods 703 of the PCB separation device 700. In this state, when the compression roller rods 703 are moved upwards by the respective main cylinders 706 and thus push the corresponding clamps 46 of the hanger 4, as shown in FIG. 4, the clamps 46 are opened. Then, the PCB 2 falls from the hanger 4. The PCB 2 that is removed from the hanger 4 is discharged to the outside of the machine by the conveyor belt 119.

[110] Subsequently, the hanger clamper 675 and the hanger holding rods 658 of the descending head 602 release the hanger 4. Then, the hanger 4 which has been held by the descending head 602 is removed from the descending head 602 and falls downwards. Thereafter, the hanger 4 removed from the descending head 602 is returned by the return conveyor 150.

[I l l] Meanwhile, as stated above, in the clamp spring damage detection unit 800 according to the present invention, the load cells 801 are provided under the respective compression roller rods 703. When each compression roller rod 703 compresses the corresponding clamp 46, the corresponding load cell 801 measures the elasticity of the clamp spring 467 of the clamp 46. Each load cell 801 is constructed such that when a load is applied thereto, an electrical signal proportional to the magnitude of the load is output. Preferably, the load cell 801 comprises a strain gauge type load cell. Therefore, an electrical signal proportional to the magnitude of the elasticity of each clamp spring 467 can be obtained.

[112] Hereinafter, the clamp spring damage detection unit 800 according to the present invention will be explained in detail with reference to FIG. 10. FIG. 11 is a plan view showing the PCB separation device 700 having the clamp spring damage detection unit 800, FIG. 12 is a front view thereof, and FIG. 13 is a side view thereof.

[113] As shown in the drawings, the compression roller rods 703 which are oriented in the vertical direction are provided in the PCB separation device 700 to correspond to the respective clamps 46 of the hanger 4 that is held by the descending head 602. The compression roller rods 703 are fixed to the rod supports 704. Preferably, the rod supports 704 comprise three rod supports 704 which are arranged in a 'U' shape, and two compression roller rods 703 are mounted to each rod support 704. Furthermore, the load cells 801 which measure the elasticities of the corresponding clamp springs 467 are provided on the respective compression roller rods 703, as described above.

[114] The main cylinders 706 are provided under the respective rod supports 704 to actuate the rod support 704 upwards or downwards. In addition, guide cylinders 705 are provided under the respective rod supports 704 to guide the vertical movement of the rod supports 704. Thus, when the rod supports 704 are moved upwards by the main cylinders 706 under guidance of the guide cylinders 705, the compression roller rods 703 push the corresponding clamps 46 of the hanger 4 and thus separate the PCB 2 from the hanger 4. At this time, each load cell 801 measures the elasticity of the corresponding clamp spring. In the drawings, the reference numeral 708 denotes a base, on which the main cylinders 706 and the guide cylinders 705 are supported.

[115] Meanwhile, there is a probability of a problem in that the seating frame 45 or the support bar 44 are bent upwards by repeatedly applying pressure from the compression roller rods 703 to the hanger 4. Therefore, to prevent the seating frame 45 or the support bar 44 from being bent upwards, the seating frame holding device 720 is further provided.

[116] The seating frame holding device 720 functions to reliably hold the seating frame 45 or the support bar 44 before the compression roller rods 703 compress the clamps 46. As shown in FIG. 11, the seating frame holding device 720 includes a plurality of holders 721 which holds or releases the seating frame 45 or the support bar 44 depending on a direction of horizontal movement thereof, and horizontal cylinders 723 which actuate the holders 721 in the horizontal directions. Furthermore, the seating frame holding device 720 may further include vertical cylinders 725 which adjust the heights of the holders 721. Here, the holders 721 and the horizontal cylinders 723 are supported by a support frame 726.

[117] In the above-mentioned construction, before the compression roller rods 703 compress the clamps 46, the horizontal cylinders 723 are operated, so that the holders 721, each of which has a holding depression 722 therein, hold the periphery of the seating frame 45 or the support bar 44. Here, the holding depression 722 which is formed in the front end of each holder 721 has a shape appropriate to insert the periphery of the seating frame 45 or the support bar 44 thereinto. After the process of separating the PCB 2 from the hanger 4 has been completed, the horizontal cylinders 723 are retracted backwards, thus releasing the hanger 4 from the holder 721.

[118] FIGS. 12 and 14 show enlargements of one compression roller rod 703 and the load cell 801 which is provided under the compression roller rod 703. As shown in the drawings, each compression roller rod 703 includes a movable part 871 which is provided so as to be movable in the vertical direction, and a stationary part 872 which is fixed to the corresponding rod support 704. The movable part 871 includes two vertical sidewalls 874 which are integrally provided on the upper end of the movable part 871, and a support shaft 875 which is provided between the two vertical sidewalls 874 and is oriented in the horizontal direction. At least one roller 876 is rotatably provided on the support shaft 875.

[119] Guide depressions 883 are formed in the stationary part 872 and guide the movable part 871. Furthermore, a seating depression 884 is formed in the movable part 871, and the load cell 801 is installed in the seating depression 884 so as to be able to contact the lower surface of the movable part 871. Thus, the load cell 801 is moved upwards or downwards in conjunction with the movable part 871 and transfers pressure to the compression roller rod 703, thus measuring the elasticity of the corresponding clamp spring 467.

[120] Referring to FIG. 10, the control unit 802 which is electrically connected to the load cells 801 compares the elasticities of the clamp springs 467 that are measured by the corresponding load cells 801 to the reference elasticity. If the elasticity of a certain clamp spring 467 is less than the reference elasticity, the control unit 802 determines that the clamp spring is damaged and outputs a control signal indicating the determination result. In detail, the control unit 802 sends the control signal both to the drive unit 834 of the bad hanger removal unit 830 and to the drive unit 854 of the new hanger feed unit 850 or to a display (not shown).

[121] As shown in the drawing, the control unit 802 includes a reception unit 803 which receives electrical signals, and a main processor 805 which compares the electrical signals transmitted from the load cells 801 to a preset reference pressure value and determines whether the clamp springs are damaged. The control unit 802 further includes a transmission unit 807 which transmits a control signal output from the main processor 805 to the outside, an input unit 804 which inputs the reference pressure value, a memory unit 806 which stores data input by the input unit 804, and a power supply unit 808 which supplies power.

[122] As shown in FIGS. 5 and 9, the distorted hanger detection unit 810 measures whether the horizontal rods 42 and 43 of each hanger 4 that is returned along the return conveyor 150 maintain the level state. If a difference in height between the horizontal rods 42 and 43 is greater than a reference value, the distorted hanger detection unit 810 determines the hanger 4 as a bad hanger, the horizontal rods of which are distorted.

[123] FIG. 15 is a view showing one embodiment of the distorted hanger detection unit

810. In this embodiment, the distorted hanger detection unit 810 includes a plurality of distance measurement sensors 811 which are provided above the return conveyor 150 at a predetermined height and measure the distances by which the distance measurement sensors 811 are respectively spaced apart from the upper and lower horizontal rods 42 and 43 of each of the hangers 4 that are carried along the return conveyor 150. Preferably, each distance measurement sensor 811 is a non-contact sensor which emits infrared rays or ultrasonic waves and receives the infrared rays or ultrasonic waves reflected by the corresponding horizontal rod 42, 43, thus measuring the distance between the sensor and the horizontal rod 42, 43. Here, the distance measurement sensors 811 may be provided below the return conveyor 150.

[124] FIGS. 16, 17 and 18 respectively are a plan view, a front view and a side view showing another embodiment of the distorted hanger detection unit 810.

[125] As shown in the drawings, in this embodiment, the distorted hanger detection unit 810 includes a plurality of distance measurement sensors 811 which are provided above the return conveyor 150 at a predetermined height, and a hanger lift device 820 which lifts one hanger 4 that is returned by the return conveyor 150 such that the horizontal rods 42 and 43 of the hanger 4 are brought into contact with the respective distance measurement sensors 811 at predetermined pressures. The distorted hanger detection unit 810 further includes the control unit 802 which is electrically connected to the distance measurement sensors 811. The control unit 802 compares the difference in the distance between the distance measurement sensors 811 and the respective horizontal rods to a reference distance difference. If the difference in the distance between the distance measurement sensors 811 and the respective horizontal rods is greater than the reference distance difference, the control unit determines the hanger 4 as a distorted hanger, thus outputting a control signal indicating the result of the determination of the control unit.

[126] Here, each of the distance measurement sensors 811 is a kind of pressure sensor which measures a distance using pressure which is applied thereto when it comes into contact with the corresponding horizontal rod 42, 43. If the measured pressure is equal to a preset pressure, it is determined that the corresponding horizontal rod maintains the level state. If the measured pressure is greater than the preset pressure, it is determined that the horizontal rod is bent upwards, and if the measured pressure is less than the preset pressure, it is determined that the horizontal rod is bent downwards. For this, the distance measurement sensors 811 are provided above the return conveyor 150 at positions spaced apart from the return conveyor 150 at predetermined heights. The distance measurement sensors 811 must be fixed such that they are disposed at the same height.

[127] The hanger lift device 820 includes two arms 828 which lift the hanger 4 that has been carried along the return conveyor 150 at a predetermined height and maintain the hanger 4 horizontal, a drive unit 821 which moves the arms 828 upwards or downwards, and a guide unit 891 which guides the vertical movement of the arms 828. [128] The drive unit 821 includes a motor 822, a belt 828 and a pulley 824 which convert the rotating force of the motor into the vertical linear motion. The guide unit 891 includes a slide block 893 which is moved upwards or downwards in conjunction with the belt 823, and a guide rod 895 which guides the vertical movement of the slide block 893. Furthermore, V-shaped notches 889 are formed in the upper surfaces of the arms 828, so that the upper and lower horizontal rods 42 and 43 of one hanger 4 can be seated into the V-shaped notches 889.

[129] Meanwhile, the distorted hanger detection unit 810 includes a stopper unit 850 which decelerates or stops the return conveyor 150. Preferably, the stopper unit 850 includes first and second detecting sensors 809 and 839 which sense the position of the hanger 4. The first and second detecting sensors 809 and 839 sense the position of the hanger 4 that is being carried by the return conveyor 150 and thus decelerates or stops the return conveyor 150 depending on the position of the hanger 4. Preferably, as shown in FIG. 16, the return conveyor 150 comprises at least two conveyors 150 and 150' which are arranged in a line, so that even though one conveyor is decelerated or stopped, the entire return conveyor can be prevented from being stopped.

[130] Furthermore, the distorted hanger detection unit 810 further includes a stopper 851 which stops each of the hangers 4 at the same preset position. The stopper 851 re- tractably protrudes upwards from the return conveyor 150 in conjunction with the first and second detecting sensors 809 and 839. In detail, when necessary, the stopper 851 is moved upwards and protruded from the return conveyor 150 by a cylinder 852 which is provided under the return conveyor 150, thus stopping each of the hangers 4 at the same preset position. In the drawings, the reference numeral 851 denotes a guide cylinder for guiding the vertical movement of the stopper 851.

[131] As shown in FIGS. 5, 9 and 19, the bad hanger removal unit 830 includes a first slider 831 which is spaced apart from the return conveyor 150 by a predetermined height, and first guide rails 833 which horizontally move the first slider 831 in the direction perpendicular to the direction in which the return conveyor 150 moves the hangers. The bad hanger removal unit 830 further includes a plurality of first hanger clampers 835 which are provided below the lower surface of the first slider 831 to hold the upper and lower horizontal rods 42 and 43 of one selected from among the hangers 4 that are returned along the return conveyor 150, and a plurality of first vertical cylinders 836 which are provided under the lower surface of the first slider 831 and move the first hanger clampers 835 upwards or downwards. The bad hanger removal unit 830 further includes a drive unit 834 which controls the horizontal movement of the first slider 831 and the extension or contraction of the first hanger clampers 835 and the first vertical cylinders 836. The drive unit 834 may include a motor and a switch or a hydraulic pump and a hydraulic controller. [132] The new hanger feed unit 850 which is disposed ahead of the bad hanger removal unit 830 includes a second slider 851 which is spaced apart from the return conveyor 150 by a predetermined height, and second guide rails 853 which horizontally move the second slider 851 in the direction perpendicular to the direction in which the return conveyor 150 moves the hangers. The new hanger feed unit 850 further includes a plurality of second hanger clampers 855 which are provided below the second slider 851 to hold upper and lower horizontal rods 42 and 43 of a new hanger 4, and a plurality of second vertical cylinders 856 which are provided under the lower surface of the second slider 851 and move the second hanger clampers 855 upwards or downwards. The new hanger feed unit 850 further includes a second drive unit 854 which controls the horizontal movement of the second slider 851 and the operation of the second hanger clampers 855 and the vertical cylinders 856. The second drive unit 854 is electrically connected to the control unit 802.

[133] The operation of the bad hanger detection unit according to the present invention will be described with reference to FIGS. 5, 9 and 10 through 13.

[134] The curing machine according to the present invention repeatedly conducts the operation of carrying the hangers 4 rearwards using the feed conveyor 130 and returning the hangers 4 forwards using the return conveyor 150 which is provided below the feed conveyor 130. Here, the hangers 4 that are returned forwards by the return conveyor 150 are moved upwards by the hanger ascending device 200 and then hung on the feed conveyor 130 again. The hangers 4 that are carried rearwards by the feed conveyor 130 are moved downwards by the hanger descending device 600 and supplied to the return conveyor 150. Thus, the hangers 4 sequentially circulate in the machine body 111.

[135] The PCBs 2 are held by the corresponding hangers 4 that are carried rearwards by the feed conveyor 130 and thus are carried rearwards along with the hangers 4. Here, the PCBs 2 are mounted to the corresponding hangers 4 by the hanger mounting device 300 which is provided on the front end of the machine body 111. The PCBs 2 are separated from the hangers 4 by the PCB separation device 700 which is provided on the rear end of the machine body 111. Each PCB 2 is seated onto the seating frame 45 of the corresponding hanger 4 and held by the clamps 46 of the hanger 4.

[136] The PCBs 2 that are held by the corresponding hangers 4 are treated through a curing process while being carried rearwards. Thereafter, each of the PCBs 2 that are completely treated through the curing process is moved downwards by the hanger descending device 600 and oriented in the horizontal direction along with the corresponding hanger 4. Subsequently, the compression roller rods 703 of the PCB separation device 700 push the respective clamps 46 of the hanger 4, thus separating the PCB 2 from the hanger 4. [137] The operation of detecting whether the clamp springs of each of the hangers 4 are damaged is performed when the compression roller rods 703 of the PCB separation device 700 push the respective clamps 46 of the hanger 4 to separate the PCB 2 from the hanger 4. In detail, when the compression roller rods 703 of the PCB separation device 700 push the respective clamps 46 of the relevant hanger 4 to separate the PCB 2 from the hanger 4, the load cells 801 which are provided under the respective compression roller rods 703 measure the elasticities of the respective clamp springs 467. The control unit 802 compares the elasticity of each clamp spring 467 measured by the corresponding load cell 801 to the reference elasticity value and thus determines by discrimination whether the clamp spring 467 is damaged.

[138] Thereafter, the hanger 4 from which the PCB 2 was removed is separated from the hanger descending device 600 and is placed onto the return conveyor 150. While the hanger 4 is returned forwards by the return conveyor 150, the operation of detecting whether the hanger 4 is distorted is performed. In detail, the distance measurement sensors 811, which are provided above or below the return conveyor 150 at positions spaced apart from the return conveyor 150 by predetermined distances, measure the heights of the horizontal rods 42 and 43 of the hanger 4, in other words, the distances between the horizontal rods 42 and 43 and the corresponding distance measurement sensors 811. The control unit 802 determines whether the hanger is a bad hanger in such a way as to compare a difference between distances between the horizontal rods 42 and 43 and the corresponding distance measurement sensors 811 to the reference distance difference or compare contact pressures between the horizontal rods 42 and 43 and the corresponding sensors to a reference pressure.

[139] If the hanger 4 is determined as a bad hanger by the clamp spring damage detection unit 800 or the distorted hanger detection unit 810, the drive unit 834 of the bad hanger removal unit 830 is operated under the control of the control unit 802, so that the first slider 831, the first hanger clampers 835 and the first vertical cylinders 836 are actuated by the operation of the drive unit 834, thus removing the bad hanger from the return conveyor 150.

[140] As such, in the case where one hanger 4 is determined as a bad hanger and thus removed, the drive unit 854 of the new hanger feed unit 850 is operated under the control of the control unit 802, so that the second slider 851, the second hanger clamper 855 and the second vertical cylinders 856 are actuated by the operation of the drive unit 854, thus feeding a new hanger onto the return conveyor 150.

[141] As described above, in the present invention, every time when each of PCBs is separated from a corresponding hanger, a clamp spring damage detection unit can detect whether clamp springs of the hanger are damaged using load cells and a control unit. Furthermore, every time when each of the hangers is returned forwards by a return conveyor, a distorted hanger detection unit can detect whether horizontal rods of the hanger maintain the level state using distance measurement sensors. In addition, a bad hanger removal unit and a new hanger feed unit can remove a bad hanger from the return conveyor and feed a new hanger depending on a control signal of the control unit. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, the scope and spirit of the invention is not limited to the above- described embodiments or attached drawings. Furthermore, it should be recognized that various modifications and changes may be made to the invention by those skilled in the art which also fall within the scope of the invention as defined by the appended claims.

Claims

[1] A hanger type curing machine having a bad hanger detection unit, the curing machine including a plurality of hangers circulating along a conveyor, each of the plurality of hangers having a plurality of clamps to hold a PCB (printed circuit board), the bad hanger detection unit including a clamp spring damage detection unit, comprising: a hanger descending device to separate the hangers from the conveyor and orient the hangers in a horizontal direction; a plurality of compression roller rods provided to correspond to the respective clamps of each of the hangers; a main cylinder to move the compression roller rods to the respective clamps of the hanger to open the clamps; a load cell provided under a lower end of each of the compression roller rods, the load cell being compressed by the compression roller rod, thus measuring an elasticity of a clamp spring of the corresponding clamp; and a control unit electrically connected to the load cells, the control unit comparing each of the elasticities of the clamp springs measured by the load cells to a preset reference elasticity and determining the hanger as a bad hanger when the elasticity of the clamp spring of at least one clamp is less than the reference elasticity, and outputting a control signal indicating the determination result, whereby the clamp spring damage detection unit detects whether each of the clamp springs of the hanger is damaged, every time when the PCB is separated from the corresponding hanger.

[2] A hanger type curing machine having a bad hanger detection unit, the curing machine including a plurality of hangers, each of which has two horizontal rods to hold a PCB having a predetermined size, the hangers being returned by a return conveyor in a horizontally oriented state, the bad hanger detection unit including a distorted hanger detection unit, comprising: a plurality of distance measurement sensors provided above the return conveyor at predetermined heights at positions corresponding to opposite ends of the horizontal rods of each of the hangers that are returned by the return conveyor; a stopper unit to stop each of the hangers that are returned by the return conveyor at a constant position; a hanger lift device to lift the hanger that is stopped by the stopper unit to a predetermined height such that the horizontal rods of the hanger come into contact with the corresponding distance measurement sensors; and a control unit electrically connected to the distance measurement sensors, the control unit determining the hanger as a distorted hanger when a difference in distances or pressures measured by the distance measurement sensors is beyond a predetermined limit, and outputting a control signal indicating the determination result, whereby the distorted hanger detection unit detects whether the hanger is distorted, every time when the hanger is returned along the return conveyor.

[3] A hanger type curing machine having a bad hanger detection unit, the curing machine including: a plurality of hangers, each of which has a plurality of clamps to hold a PCB; a feed conveyor to carry the hangers holding the PCBs rearwards while the hangers are hung on the feed conveyor in a vertically oriented state; a return conveyor provided below the feed conveyor at a position spaced apart from the feed conveyor by a predetermined distance, the return conveyor returning each of the hangers forwards in a horizontally oriented state after the PCB is separated from the hanger; a machine body having the feed conveyor and the return conveyor therein; a hanger ascending and PCB mounting unit provided ahead of the machine body, the hanger ascending and PCB mounting unit moving upwards each of the hangers that are returned and placing the hanger upright, and hanging the hanger on the feed conveyor after mounting a subsequent PCB to the hanger; and a hanger descending and PCB separating unit provided behind the machine body, the hanger descending and PCB separating unit moving downwards each of the hangers that are carried rearwards and orienting the hanger in a horizontal direction, and placing the hanger onto the return conveyor after separating the PCB from the hanger, wherein the bad hanger detection unit comprises: a clamp spring damage detection unit comprising: a hanger descending device to hold each of the hangers that are carried rearwards by the feed conveyor and move the hanger downwards, and orient the hanger such that the hanger is parallel to a ground and the clamps of the hanger face the ground; a plurality of compression roller rods provided to correspond to the respective clamps of the hanger that is held by the hanger descending device; a main cylinder to move the compression roller rods to the respective clamps of the hanger to open the clamps; a load cell provided under a lower end of each of the compression roller rods, the load cell being compressed by the compression roller rod, thus measuring an elasticity of a clamp spring of the corresponding clamp; and a control unit electrically connected to the load cells, the control unit comparing an elasticity of each of the clamp springs measured by the load cells to a preset reference elasticity and determining that the hanger is a bad hanger when the elasticity of at least one clamp spring is less than the reference elasticity, and outputting a control signal indicating the determination result; and a distorted hanger detection unit comprising: a plurality of distance measurement sensors provided above the return conveyor at predetermined heights at positions corresponding to opposite ends of horizontal rods of each of the hangers that are returned by the return conveyor; a stopper unit to stop each of the hangers that are returned by the return conveyor at a constant position; a hanger lift device to lift the hanger that is stopped by the stopper unit to a predetermined height such that the horizontal rods of the hanger come into contact with the corresponding distance measurement sensors; and a control unit electrically connected to the distance measurement sensors, the control unit determining the hanger as a distorted hanger when a difference in distances or pressures measured by the distance measurement sensors is beyond a predetermined limit, and outputting a control signal indicating the determination result, whereby the bad hanger detection unit detects whether each of the clamp springs of the hanger is damaged, every time when the PCB is separated from each of the hangers, and detects whether the hanger is distorted every time when the hanger is returned along the return conveyor.

[4] The hanger type curing machine having the bad hanger detection unit according to any one of claims 1, 2 and 3, wherein each of the hangers comprises: a seating frame provided at a central position between the upper and lower horizontal rods, the seating frame having a rectangular shape and supporting a periphery of the PCB; and the plurality of clamps integrally provided on the seating frame to hold the periphery of the PCB.

[5] The hanger type curing machine having the bad hanger detection unit according to claim 4, wherein each of the clamps comprises: a rotating plate provided so as to be rotatable around a rotating shaft; and the clamp spring fitted over the rotating shaft to apply elastic force to the rotating plate in a direction in which the rotating plate holds the PCB.

[6] The hanger type curing machine having the bad hanger detection unit according to claim 1 or 3, wherein the clamp spring damage detection unit further comprises: a seating frame holding device to hold the seating frame or a support bar provided with the clamps, before the compression roller rods compress the respective clamps, wherein the seating frame holding device comprises: a plurality of holders respectively having holding depressions on ends thereof to hold or release the seating frame or the support bar using horizontal movement of the holders; a horizontal cylinder to actuate the holders in the horizontal directions; a support frame supporting the horizontal cylinder and the holders thereon; and a vertical cylinder to actuate the support frame upwards or downwards.

[7] The hanger type curing machine having the bad hanger detection unit according to claim 1 or 3, wherein each of the compression roller rods comprises: a movable part, having two vertical sidewalls integrally provided at positions spaced apart from each other by a predetermined distance, and a support shaft provided between the vertical sidewalls in a horizontal direction, with at least one rotating roller provided on the support shaft so as to be rotatable; and a stationary part, having a guide depression to guide vertical movement of the movable part, and a seating depression supporting the load cell therein such that the load cell comes into contact with the movable part and is operated in conjunction with the movable part.

[8] The hanger type curing machine having the bad hanger detection unit according to claim 2 or 3, wherein the stopper unit of the distorted hanger detection unit comprises: at least one detecting sensor to sense positions of the hangers that are returned by the return conveyor and decelerate or stop the return conveyor; a stopper to stop each of the hangers at the constant position in such a way as to protrude from the return conveyor upwards; and a cylinder to actuate the stopper upwards or downwards depending on a control signal of the detecting sensor.

[9] The hanger type curing machine having the bad hanger detection unit according to claim 2 or 3, wherein the hanger lift device of the distorted hanger detection unit comprises: two arms having V-shaped notches, into which the horizontal rods of each of the hangers that are returned by the return conveyor are seated; a drive unit including a motor to move the two arms upwards or downwards, and a belt and a pulley to convert rotating motion of the motor into vertical linear motion; a slide block connected to the belt to move the two arms upwards or downwards; and at least one guide rod to guide the vertical movement of the two arms.

[10] The hanger type curing machine having the bad hanger detection unit according to any one of claims 1, 2 and 3, wherein the control unit of the clamp spring damage detection unit and the control unit of the distorted hanger detection unit are integrated into a single control unit.

[11] The hanger type curing machine having the bad hanger detection unit according to any one of claims 1, 2 and 3, further comprising a bad hanger removal unit, comprising: a first slider provided above the return conveyor at a position spaced apart from the return conveyor by a predetermined height; a first guide rail to guide the first slider such that the first slider is horizontally movable in a direction perpendicular to a direction in which the return conveyor moves the hangers; a plurality of first hanger clampers provided under a lower surface of the first slider to hold the upper and lower horizontal rods of one bad hanger selected from among the hangers that are moved by the return conveyor; a plurality of first vertical cylinders provided in the first slider to move the first hanger clampers upwards or downwards; and a first drive unit to control the horizontal movement of the first slider and the actuation of the first hanger clampers and the first vertical cylinders depending on a control signal of the clamp spring damage detection device, whereby the bad hanger removal unit removes the bad hanger having a damaged clamp spring from the return conveyor.

[12] The hanger type curing machine having the bad hanger detection unit according to claim 11, further comprising a new hanger feed unit, comprising: a second slider provided above the return conveyor at a position spaced apart from the return conveyor by a predetermined height; a second guide rail to guide the second slider such that the second slider is horizontally movable in a direction perpendicular to a direction in which the return conveyor moves the hangers; a plurality of second hanger clampers provided under a lower surface of the second slider, the second hanger clampers holding upper and lower horizontal rods of a new hanger to feed the new hanger onto the return conveyor; a plurality of second vertical cylinders provided in the second slider to move the second hanger clampers upwards or downwards; and a first drive unit to control the horizontal movement of the second slider and the actuation of the second hanger clampers and the second vertical cylinders depending on a control signal of the clamp spring damage detection device, whereby the new hanger feed unit feeds the new hanger onto the return conveyor in place of the bad hanger that is removed from the return conveyor by the bad hanger removal unit.

[13] The hanger type curing machine having the bad hanger detection unit according to claim 10, wherein the control unit comprises: a reception unit to receive electrical signals from the load cells or the distance measurement sensors; a main processor to convert the electrical signals input from the load cells or the distance measurement sensors into elasticity values or distance values or compare the electrical signals to the preset reference elasticity pressure value, and determine whether each of the hangers is a bad hanger; a transmission unit to transmit a control signal output from the main processor to an outside; an input unit to input reference value data, a memory unit to store the data input by the input unit; and a power supply unit to supply power.