JP2016072460A - Component holding head of surface mounting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detection accuracy of a sensor for detecting a component holder (nozzle) in a component holding head of a surface mounting machine.SOLUTION: A component holding head of a surface mounting machine includes a plurality of spindles arranged along a circumferential direction of a rotary head 40 that is attached to a head body so as to be rotatable in an R direction around a vertical axis of the head body, and a component holder 42 attached to a lower end of each of the spindles. The component holding head includes an optical sensor 30 of a reflection type that detects the component holder 42a that reaches a predetermined position by rotating in the R direction. The optical sensor 30 includes a light emission part that emits light toward a reflection surface 42b in an outer periphery of the component holder 42a, and a light receiving part that receives light reflected on the reflection surface 42b, the parts being arranged on the same axis. The optical sensor 30 is also arranged so that an optical axis of light emitted from the light emission part is displaced from a position of the reflection surface 42b on a vertical center axis of the component holder 42a to point to a position of the reflection surface 42b on a downstream side in a rotation direction in the R direction.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a component holding head having a component holder for holding components in a surface mounter for mounting components (electronic components) such as IC chips on a substrate.

  In general, a surface mounter moves a component holding head above a component supply unit, and causes a nozzle as a component holder provided in the component holding head to move down and ascend to the lower end of the nozzle. The components are sucked up and picked up, and then the component holding head is moved to the upper side of the board, and then the nozzle is lowered and raised again to mount the parts at predetermined coordinate positions on the board. ing.

  As described above, when picking up a component by causing the nozzle to move down and up, if the lowering stroke of the nozzle is too large, the lower end of the nozzle strongly presses the upper surface of the component and destroys the component. If the descending stroke is too small, the nozzle cannot land on the top surface of the part and picks up the part. The same applies to the case where the component is mounted on the substrate. If the lowering stroke of the nozzle is too large, the component adsorbed on the lower end of the nozzle is strongly pressed against the substrate and destroyed. If the descending stroke is too small, the component cannot land on the top surface of the board, and the component is mismounted. Therefore, the lowering stroke of the nozzle must be accurately controlled.

  As a method for accurately controlling the lowering stroke of the nozzle, Patent Document 1 proposes a method using detection means (sensor for detecting the nozzle) that detects the landing of the nozzle. In addition, the applicant of the present application similarly uses a method using a reflection type optical sensor (optical fiber sensor) as a sensor for detecting a nozzle in Japanese Patent Application No. 2013-212220 as a method for accurately controlling the downward stroke of the nozzle. Proposed. This optical fiber sensor has a light emitting unit that emits light toward a reflecting surface on the outer periphery of the nozzle and a light receiving unit that receives reflected light reflected by the reflecting surface. Detect.

  In this way, when a reflective optical sensor (optical fiber sensor) is used to detect a nozzle based on a change in the amount of received light, the amount of received light before detecting the nozzle from the point of preventing false detection and improving detection accuracy. Is desired to be as constant as possible. From this point, conventionally, the optical axis of the light emitted from the light emitting unit is directed to the central axis in the vertical direction of the nozzle to be detected, but the detection accuracy is not always sufficient.

Japanese Patent No. 3543044

  The problem to be solved by the present invention is to improve the detection accuracy of a sensor for detecting a component holder (nozzle) in a component holding head of a surface mounter.

  As a result of studying the arrangement of sensors for detecting a component holder (nozzle) by the present inventors to solve the above-mentioned problems, the light emitting part of a reflective optical sensor for detecting the component holder will be described in detail later. If the optical axis direction of the light emitted from is offset to the downstream side in the rotation direction (R direction) of the rotary head from the vertical center axis of the component holder, the amount of received light before detecting the nozzle is stabilized at a high level. New findings were obtained. The present invention has been completed based on this finding. Specifically, the present invention provides a component holding head for a surface mounter as described in (1) to (3) below.

(1) A plurality of spindles are arranged along the circumferential direction of a rotary head that is attached to the head body so as to be rotatable in the R direction around the vertical axis, and a component holder is attached to the lower end of each spindle. In component holding head of surface mounter,
A reflective optical sensor that detects the component holder that rotates in the R direction and arrives at a specific position is provided.
The optical sensor has a light emitting unit that emits light toward a reflection surface on the outer periphery of the component holder at the specific position, and a light receiving unit that receives the reflected light reflected by the reflection surface, on the same axis. In addition, the optical axis of the light emitted from the light emitting unit is lower than the position of the reflecting surface on the vertical center axis of the component holder at the specific position on the reflecting surface on the downstream side in the rotation direction in the R direction. A component holding head of a surface mounter, wherein the component holding head is arranged to be offset so as to direct the position.

(2) The component holding head of the surface mounter according to (1), wherein the amount of the offset is set such that a change in the amount of light received by the light receiving unit is minimized with respect to a change in the amount of offset. .

(3) The optical sensor detects a component holder by a change in the amount of received light with respect to a predetermined threshold, and the threshold is set based on the amount of received light in a stable region of the amount of received light by the light receiving unit. Or the component holding head of the surface mounting machine as described in (2).

  According to the present invention, in a reflection type optical sensor that detects a component holder (nozzle), the amount of received light before detecting the component holder is stabilized at a high level. Thereby, the detection precision of the component holder by the said sensor improves, and the downward stroke of a component holder etc. can be controlled more appropriately.

It is a perspective view which shows the whole structure of the components holding head of this invention. 2A and 2B are diagrams showing a mechanism for raising and lowering a spindle in the Z direction in the component holding head of FIG. 1, wherein FIG. 1A is a front view, FIG. 1B is a left side view, and FIGS. . It is explanatory drawing which shows the structure around a raising / lowering member in the mechanism which raises / lowers the spindle of FIG. 2 to a Z direction. It is a perspective view which shows the principal part of the optical fiber sensor used in the component holding head of FIG. 1 including the attachment state. FIG. 2 is an enlarged perspective view showing a section of a nozzle portion mounted on a lower end of a spindle in the component holding head of FIG. 1. It is a figure which shows typically the change of the light reception amount of an optical fiber sensor when a nozzle lands. It is a top view which shows notionally "offset" in this invention. The result of measuring the amount of light received by the light receiving portion of the optical fiber sensor by changing the offset angle θ (offset amount d) is shown (offset angle = −1.0 °). Same as above (offset angle θ = −0.5 °). Same as above (offset angle θ = 0.0 °). Same as above (offset angle θ = + 0.5 °). Same as above (offset angle θ = + 1.0 °). Same as above (offset angle θ = + 1.5 °). Same as above (offset angle θ = + 2.0 °). Based on the results of FIGS. 8A to G, the received light amount in each example is plotted against the offset angle θ.

  Hereinafter, embodiments of the present invention will be described based on examples shown in the drawings.

  FIG. 1 is a perspective view showing the overall configuration of the component holding head of the present invention.

  The component holding head 10 shown in the figure is a rotary head type component holding head, and a rotary head 40 is attached to a head body (main frame) 20 so as to be rotatable in the R direction around the vertical axis. A plurality of spindles 41 are arranged at equal intervals along the circumferential direction of the rotary head 40, and nozzles 42 are attached to the lower ends of the spindles 41 as component holders for sucking and holding components.

  The rotary head 40 rotates in the R direction by driving an R servo motor 21 installed in the head body 20. Each spindle 41 rotates in the T direction around its axis by driving a T servo motor 22 installed in the head body 20. Further, the head main body 20 is provided with a Z servo motor 23 for raising and lowering a spindle 41a (see FIG. 3) at a specific position in the Z direction along the axial direction. Since a mechanism for rotating the rotary head 40 in the R direction by driving the R servo motor 21 and a mechanism for rotating the respective spindles 41 in the T direction by driving the T servo motor 22 are well known, description thereof will be omitted. A mechanism for moving the spindle 41a up and down by driving the Z servo motor 23 will be described below.

  2A and 2B are diagrams showing a mechanism for raising and lowering the spindle 41a in the Z direction in the component holding head 10 of FIG. 1, wherein FIG. 2A is a front view, FIG. 2B is a left side view, and FIG. 2C and FIG. It is a perspective view of a part.

  A motor shaft of the Z servo motor 23 is connected to a screw shaft 24 of a ball screw mechanism, and a nut of the ball screw mechanism is attached to the screw shaft 24, and an elevating member 25 is fastened to the nut. The elevating member 25 is provided with an upper spline shaft 26 for rotation prevention and elevating guide. A pressing tool 25 a is integrally connected to the elevating member 25. Therefore, the drive of the Z servo motor 23 moves the pressing tool 25 a in the Z direction together with the lifting member 25.

  Only one lifting member 25 and pressing tool 25a are provided on the head body 20 side. When the spindle 41 is lowered, the spindle 41 to be lowered (the spindle 41a at the specific position) is selected by moving the spindle 41 relative to the pressing tool 25a, and the spindle is lowered by lowering the pressing tool 25a. 41a and the nozzle 42a attached to the lower end thereof are lowered. In this embodiment, as shown in FIG. 3, the spindle 41 is moved with respect to the pressing tool 25a by rotating the rotary head 40 in the R direction, and the spindle 41a immediately below the pressing tool 25a is lowered. There may be two or more specific positions.

  Returning to FIG. 2, the base end of the arm member 28 is connected to the elevating member 25 to which the pressing tool 25 a is connected via an adapter member 27, and the sensor holder member 29 is connected to the distal end side of the arm member 28. The optical fiber sensor 30 is connected as a sensor for detecting the nozzle. In addition, a lower spline shaft 31 is attached to the distal end side of the arm member 28 in order to guide the raising / lowering of the arm member 28 accompanying the raising / lowering of the raising / lowering member 25. The lower spline shaft 31 is fixed to the head main body 20 via a fixing member 32.

  Here, the adapter member 27 is an XY direction position adjusting member for adjusting the position of the optical fiber sensor 30 in the XY direction. That is, the adapter member 27 is connected to the elevating member 25 so that the position of the adapter member 27 can be adjusted in the XY direction within a horizontal plane perpendicular to the Z direction. Accordingly, the position in the XY direction of the arm member 28 integrated with the adapter member 27 is adjusted, and as a result, the position in the XY direction of the optical fiber sensor 30 connected to the arm member 28 is adjusted.

  The sensor holder member 29 is a Z direction position adjusting member for adjusting the position of the optical fiber sensor 30 in the Z direction. That is, the sensor holder member 29 is connected to the arm member 28 so that the position of the sensor holder member 29 can be adjusted in the Z direction. As a result, the position in the Z direction of the optical fiber sensor 30 integrally connected (held) to the sensor holder member 29 is adjusted.

  As described above, the optical fiber sensor 30 is connected to the elevating member 25 via the adapter member 27, the arm member 28, and the sensor holder member 29, but after the position adjustment by the adapter member 27 and the sensor holder member 29 is performed, It is integrated with the elevating member 25 and the pressing tool 25a. Accordingly, when the pressing tool 25a moves in the Z direction by driving the Z servo motor 23, the optical fiber sensor 30 moves in the Z direction in conjunction with this. That is, the optical fiber sensor 30 moves in the Z direction in synchronization with the movement of the spindle 41a in the Z direction due to the raising and lowering of the pressing tool 25a. The spindle 41 is always urged toward the upper initial position by an elastic body 41b (see FIG. 1) composed of two coil springs.

  The optical fiber sensor 30 has a light emitting part and a light receiving part incorporated together with an optical fiber and a lens on the same axis, and its configuration itself is well known. FIG. 4 is a perspective view showing the main part of the optical fiber sensor 30 used in the present embodiment including its mounting state. As described above, the optical fiber sensor 30 is connected to the arm member 28 via the sensor holder member 29. The optical fiber sensor 30 of the present embodiment has an eccentric collar 30a as an optical axis direction adjusting means for adjusting the optical axis direction. That is, the eccentric collar 30a is attached to the lens 30b of the optical fiber sensor 30, and the optical axis direction of the optical fiber sensor 30 is adjusted by rotating the eccentric collar 30a with respect to the lens 30b.

  Next, the basics of the sensor function of the optical fiber sensor 30 will be described.

  In this embodiment, the optical fiber sensor 30 is disposed obliquely above the nozzle 42 (nozzle 42a at the specific position) attached to the lower end of the spindle 41 as shown in FIG. And the light emission part of the optical fiber sensor 30 emits the light P diagonally downward toward the reflective surface 42b of the outer peripheral upper surface of the nozzle 42a shown in FIG. The light P is received as reflected light by the light receiving unit of the optical fiber sensor 30.

  Here, the nozzle 42 is attached to the lower end of the spindle 41 via a coil spring 43 (elastic body) as shown in FIG. Accordingly, when the nozzle 42a at the lower end of the spindle 41a is landed by the lowering of the spindle 41a at the specific position, the coil spring 43 is compressed and the vertical position of the nozzle 42a with respect to the spindle 41a changes. Specifically, the nozzle 42a relatively moves toward the lower end side of the spindle 41a.

  On the other hand, the light P emitted from the light emitting portion of the optical fiber sensor 30 is focused on the reflecting surface 42b in the initial state where the nozzle 42a is not landed by the lens 30b shown in FIG. Therefore, when the nozzle 42a lands and its vertical position changes, the amount of reflected light reflected by the reflecting surface 42b decreases, and the amount of light received by the light receiving portion of the optical fiber sensor 30 decreases (FIG. 6). reference). In this embodiment, this decrease in the amount of received light is detected by a sensor unit (not shown) of the optical fiber sensor 40. The sensor unit determines that the nozzle 42a has landed when the received light amount has decreased by a predetermined amount, for example, when the amount is equal to or less than the threshold value A shown in FIG. 6, and issues a landing detection signal.

  In this specification, the landing of the nozzle (component holder) means that the lower end of the nozzle is landed on the upper surface of the component in the component pick-up process, and the component held on the lower end of the nozzle in the component mounting process. Is a concept including both landing on the upper surface of the substrate.

  Referring to FIG. 6 again, it is preferable that the amount of received light before the landing of the nozzle 42a at the specific position is as stable as possible over time. If the temporal change in the amount of light received before the nozzle 42a lands is large, the amount of light received will be less than or equal to the threshold A even though the nozzle 42a has not landed, and a landing detection signal will be erroneously generated. is there. Further, it is preferable that the amount of received light before landing of the nozzle 42a is as high as possible. This is because if the amount of received light before the landing of the nozzle 42a is at a high level, the degree of freedom in setting the threshold A increases and the landing of the nozzle 42a can be detected more accurately.

  In the present invention, the optical axis direction of the light emitted from the light emitting portion of the optical fiber sensor 30 is offset in a specific direction in order to stabilize the received light amount before landing of the nozzle 42a at a high level.

  FIG. 7 is a plan view conceptually showing this offset. In the figure, the optical fiber sensor 30 detects the landing of the nozzle 42a that has arrived at a specific position in the manner described above. In the present invention, the optical axis of the light P emitted from the light emitting unit of the optical fiber sensor 30 is determined by the rotational direction (R) of the rotary head 40 from the position of the reflecting surface 42b on the vertical center axis C of the nozzle 42a at the specific position. The optical fiber sensor 30 is arranged so as to be offset so as to be directed to the position of the reflecting surface 42b on the downstream side in the direction). In other words, the optical axis direction of the light emitted from the light emitting portion of the optical fiber sensor 30 that detects the nozzle 42a at the specific position is downstream of the rotation direction (R direction) of the rotary head from the vertical center axis C of the nozzle 42a. An offset amount d is offset on the side.

  8A to 8G show results of measuring the amount of light received by the light receiving unit of the optical fiber sensor 30 by changing the offset amount d in FIG. 7 as a test for verifying the effect of the present invention. In the test, the offset amount d at the specific position was changed by changing the offset angle θ in the R direction of the rotary head with the specific position as a reference (zero). The relationship between the offset angle θ and the offset amount d is as shown in Table 1 below. The direction in which the optical axis direction of the light emitting part of the optical fiber sensor 30 is offset to the downstream side in the R direction is plus (+), and the offset is upstream. The direction to do was minus (-). In the test, for each example set to the offset angle θ (offset amount d) of No. A to G in Table 1, the rotary head is rotated in the R direction following the actual operation of the rotary head, and the nozzle is The time-dependent change in the amount of light received by the light receiving unit of the optical fiber sensor 30 from the time before reaching the specific position to the time when the specific position was passed was measured. Nos. A to G in Table 1 correspond to the results of FIGS.

  8A to G, the offset angle θ (offset amount d) is positive, that is, the optical axis direction of the light emitted from the light emitting portion of the optical fiber sensor 30 is the rotational direction (R direction) of the rotary head from the vertical center axis of the nozzle. ) Is offset to the downstream side, it can be seen that the amount of light received by the light receiving portion of the optical fiber sensor 30 is prevented from changing with time and the amount of received light is stabilized. Here, the upper limit of the offset angle θ (offset amount d) is inevitably determined from the precondition that the optical fiber sensor 30 detects the nozzle. Specifically, since it is a necessary condition that the optical axis direction of the light emitted from the light emitting portion of the optical fiber sensor 30 is within the range of the reflecting surface 42b of the nozzle 42a described in FIG. The upper limit of the offset angle θ (offset amount d) is determined.

  Here, the threshold value A described with reference to FIG. 6 is set based on the received light amount in the stable region of the received light amount in the temporal change of the received light amount in the example of the present invention shown in FIGS. The stable region of the received light amount is a region excluding the rising region and the falling region of the received light amount in FIGS. Thus, an accurate threshold can be set by setting the threshold based on the amount of received light in the stable region of the amount of received light, leading to an improvement in detection accuracy of the optical fiber sensor 30.

  FIG. 9 is a plot of the amount of light received in each example against the offset angle θ based on the results of FIGS. From FIG. 9, it can be seen that in the present embodiment, when the offset angle θ is + 1.0 °, the amount of received light is maximized and the change in the amount of received light is minimized with respect to the change in the offset angle θ. The fact that the change in the amount of received light with respect to the change in the offset angle θ is small means that a stable amount of received light can be obtained even if the offset angle θ (offset amount d) slightly changes due to an error or the like. This is preferable for improving and stabilizing the detection accuracy of the sensor 30. Therefore, in this embodiment, the offset angle θ is optimally + 1.0 °. The optimum value of the offset angle θ (offset amount d) varies depending on the configuration and dimensions of the rotary head, but can be obtained by performing the same test as that in FIG. 9 on the rotary head.

  The adjustment of the offset angle θ (offset amount d) is performed by adjusting the adapter member 27 (XY direction position adjusting member) and the sensor holder member 29 (Z direction position adjusting member) described in FIG. 2 and the eccentric collar 30a described in FIG. (Optical axis direction adjusting means) is used.

10 Component holding head 20 Head body (main frame)
21 R Servo Motor 22 T Servo Motor 23 Z Servo Motor 24 Screw Shaft of Ball Screw Mechanism 25 Elevating Member 25a Pressing Tool 26 Upper Spline Shaft 27 Adapter Member 28 Arm Member 29 Sensor Holder Member 30 Optical Fiber Sensor 30a Eccentric Color 30b Lens 31 Lower Spline shaft (guide member)
32 Fixing member 40 Rotary head 41, 41a Spindle 41b Bullet 42, 42a Nozzle (component holder)
42b Reflecting surface 43 Coil spring (elastic body)

Claims (3)

A surface mounter in which a plurality of spindles are arranged along the circumferential direction of a rotary head mounted so as to be rotatable in the R direction around the vertical axis with respect to the head body, and a component holder is mounted at the lower end of each spindle. In the component holding head of
A reflective optical sensor that detects the component holder that rotates in the R direction and arrives at a specific position is provided.
The optical sensor has a light emitting unit that emits light toward a reflection surface on the outer periphery of the component holder at the specific position, and a light receiving unit that receives the reflected light reflected by the reflection surface, on the same axis. In addition, the optical axis of the light emitted from the light emitting unit is lower than the position of the reflecting surface on the vertical center axis of the component holder at the specific position on the reflecting surface on the downstream side in the rotation direction in the R direction. A component holding head of a surface mounter, wherein the component holding head is arranged to be offset so as to direct the position.   2. The component holding head of the surface mounter according to claim 1, wherein the amount of the offset is set such that a change in the amount of light received by the light receiving unit is minimized with respect to a change in the amount of offset.   The said optical sensor detects a component holder by the change of the light reception amount with respect to a predetermined threshold value, The said threshold value is set based on the light reception amount in the stable region of the light reception amount by the said light-receiving part. The component holding head of the surface mounting machine described.

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