JPH0722234B2 - Chip component mounting device - Google Patents

Description

The present invention relates to a chip component mounting apparatus for automatically mounting a chip component on a printed circuit board, which increases the operation speed of a suction head and improves the accuracy of a stop position. Can be improved.

[Conventional technology]

As this type of chip component mounting device, a head support part that moves in a horizontal plane at high speed in the XY directions is provided on the conveyor that conveys the printed circuit board, and the chip component supplied from the component supply part is adsorbed on the printed circuit board. It is conventionally known that the head supporting portion is provided with a suction head for moving it to a predetermined position. The suction head includes a suction nozzle that descends to suck the chip component, and a plurality of correction arms that sandwich the chip component sucked by the suction nozzle to correct the position of the chip component with respect to the suction nozzle. There is. Then, in order to improve the positioning accuracy of the chip component when correcting the position of the sucked chip component, the conventional chip component mounting device raises the suction nozzle that sucks the chip component and stops it at a predetermined height position. After that, the position of the chip component with respect to the suction nozzle is forcibly corrected by sandwiching the chip component with the correction arm. For this reason,
The conventional suction head is provided with an actuator for raising and lowering the suction nozzle and an actuator for opening and closing the correction arm separately, and controlling both actuators sequentially to lower the suction nozzle, raise the suction nozzle,
The operation of holding the chip component by the correcting arm, releasing the holding of the chip component, and lowering the suction nozzle are sequentially performed according to a predetermined procedure (for example, Japanese Patent Laid-Open No. 57-15694).

[Problems to be Solved by the Invention]

By the way, in the above-mentioned conventional one, it is necessary to attach two actuators, an actuator for opening and closing the correction arm and an actuator for vertically moving the suction nozzle, to the suction head, and an operation mechanism for operating the correction arm by the actuator and a suction mechanism. Since the two-system operation mechanism including the operation mechanism for operating the head is required, the suction head is heavy and the inertia is inevitably large. Therefore, there are problems that the speed of starting and stopping the suction head is poor, and it is difficult to improve the accuracy of the stop position of the suction head.

In order to improve the efficiency of mounting work of chip parts, it is required to increase the operating speed of the suction head and to improve the accuracy of the stop position, but in order to meet this request, the suction head should be used as much as possible. It is necessary to reduce the weight.

In order to make the suction head as light as possible, the present invention provides a correction arm opening / closing operation mechanism so that the opening / closing operation of the correction arm and the lifting operation of the suction means can be performed directly and directly by a single drive means. The task is to devise.

[Means taken to solve the problem]

 The measures taken to solve the above problems are as follows.

That is, the suction head includes suction means at its lower end that moves up and down and sucks the chip component, and the chip component sucked by the suction means is sandwiched to correct the position of the chip component with respect to the suction means. Further, there is provided a pair of correction arms, which can be moved up and down relatively with respect to the suction means, and which is opened to open the correction arm and which is moved up to close the correction arm, and the correction arm control means. Drive means for moving the correction arm control means up and down, wherein the correction arm control means is a hollow cylindrical body provided outside the suction means and concentric with the suction means. The correction arm control means is lowered by a predetermined stroke with respect to the suction means, and the correction arm is opened by the correction arm opening / closing operation section. Is that which is adapted to be lowered by pressing the suction unit by the subsequent correction arm control means.

[Action]

To pick up the chip component at the chip component suction position,
The correction arm control means is lowered by the driving means. By this lowering, the correction arm opening / closing operation portion of the correction arm control means pushes and opens the correction arm, and then the correction arm control means pushes down the suction means and moves down, and the suction means at the lower end abuts the chip component. The suction means contacts the chip component and then sucks the chip component.

When the correction arm control means is raised again by the driving means after the chip component is sucked, the suction means moves up following the rise of the correction arm control means and stops at a predetermined position. By the subsequent rise of the correction arm control means,
The correction arm held in the opened state by the correction arm control means starts to close, and the chip component sucked by the suction means is caught by the correction arm, and the position of the chip component with respect to the suction means is caught by the correction arm. Will be fixed.

After moving the suction head over the substrate on the conveyor,
The correction arm control means is lowered again by the driving means. By this lowering, the correction arm is pushed open in the same manner as described above, and the sandwiching of the correction arm with respect to the chip is released, and then the suction means descends to place the chip component on the substrate.

As described above, the operations of opening the correction arm, lowering the suction means, raising the suction means, and closing the correction arm are sequentially performed by raising and lowering the correction arm control means which is a hollow cylindrical body concentric with the suction means. Therefore, in order to perform the two operations of opening / closing the correction arm and raising / lowering the suction means, it suffices that there is one drive means for moving the correction arm control means up and down, and the correction arm control means is the suction means. Since it is a concentric hollow cylinder, it can be compactly incorporated in the suction head, and further, two operations of opening and closing the correction arm and raising and lowering the suction means can be directly performed by raising and lowering the correction arm control means. Therefore, a special operating mechanism for operating the correction arm by the correction arm control means is not required. Therefore, the suction head can be remarkably reduced in size and weight as compared with the prior art.

〔Example〕

 Next, embodiments will be described with reference to the drawings.

FIG. 11 shows a side surface of the chip component mounting apparatus, and a conveyor 2 as a transfer path is horizontally installed on the upper surface of the cabinet 1. The printed board 3 is conveyed from one side by the conveyor 2, and when the printed board 3 reaches the chip component mounting position P ₁ , the feeding of the conveyor 2 is temporarily stopped.

A frame 4 is arranged above the conveyor 2, and the frame 4 has guide rails 5 orthogonal to the conveyor 2,
Guided by 5, it is reciprocated in a horizontal plane parallel to the conveyor 2 in a direction orthogonal to the conveyor 2, that is, in the Y direction. The guide rails 5, 5 are attached to one end of the frame 4.
A lead screw 6 parallel to the screw is screwed. By rotating the lead screw 6 by a motor 7, the frame 4 is fed in the Y direction.

A head support portion 8 is supported by the frame 4, and the head support portion 8 is guided by a guide rail 9 extending along the conveyor 2 to feed the conveyor 2, that is, X direction.
It is reciprocated in the direction. A lead screw 10 parallel to the guide rail 9 is screwed onto the head support portion 8.
Is rotated by the motor 11, the head support 8 is fed in the X direction. Therefore, the head support portion 8 is moved to an arbitrary position in the horizontal plane parallel to the conveyor 2 by the reciprocating movement in the X direction and the feeding of the frame 4 in the Y direction.

On the other hand, a component supply unit 12 is provided on the cabinet 1 on both sides of the conveyor 2 in between. The component supply unit 12 of this embodiment includes a plurality of adhesive tapes 13 wound around reels. Chip components 14 ... Having a rectangular parallelepiped shape are attached to the adhesive tape 13 at equal intervals, and the adhesive tape 13 is attached to the feeding end as shown in FIG. A ratchet type feeding mechanism 16 for intermittently feeding the tape 13 is incorporated.

The feed mechanism 16 is provided with a rickshaw 19 having a ratchet wheel 17 and a claw 18 that is caught by the ratchet wheel 17, and the ratchet wheel 17 is rotated integrally with a feeder wheel (not shown) that meshes with the feed hole of the adhesive tape 13. . Then, the rickshaw 19 is rotated by a certain angle in the direction of arrow A by pushing the pressing rod 20 downward, and then pulled back by the spring 21, and the claw 18 rotates the ratchet wheel 17 by a certain angle in the direction of arrow B by this pulling back.
By the rotation of the ratchet wheel 17, the adhesive tape 13 is fed out at a constant pitch, and the tip part 14 of the chip component 14 is positioned at the suction position P ₂ .

By the way, the head supporting portion 8 has three suction heads 22.
.. are installed in parallel. The suction head 22 transfers the chip component 14 positioned at the suction position P ₂ to a predetermined position on the printed circuit board 3 at the chip component mounting position P ₁ .

The mechanism and structure of the suction head 22 will be described below with reference to FIGS. 1 to 6.

The head body 23 is supported by the head support portion 8,
A cylinder 24 and a mounting hole 25 having a diameter larger than that of the cylinder 24 are coaxially formed in the head body 23. A lid member 26 that closes the upper end release portion of the cylinder 24 is attached to the upper surface of the head body 23, and an intermediate member 27 that closes the lower end release portion of the cylinder 24 is fitted in the mounting hole 25. There is.

Inside the mounting hole 25, a cylindrical guide 30 is coaxially supported via a sleeve 28 and a bearing 29.
The lower end of 30 is projected below the mounting hole 25. A hollow shaft part 31 is inserted into the cylinder 24 and the guide 30, and the shaft part 31 is an outer shaft.
It has a double structure in which 32 and the inner shaft 33 are fitted so as to be slidable in the axial direction. The inner shaft 33 constitutes a suction means, and a vacuum passage 34 extending in the axial direction is formed therein.
There is. The upper end of the shaft part 31 penetrates through the lid member and projects upward, and the upper end of the inner shaft 33 projects higher than the outer shaft 32. The upper end of the inner shaft 33 has a bearing 35. The end cap 36 is fitted in through. Then, the vacuum passage 34 in the inner shaft 33
Is a hose 37 communicating with the end cap 36 and the head body
It communicates with a vacuum pump 39 via a communication passage 38 in 23.
Further, the lower end portion of the inner shaft 33 extends below the outer shaft 32, and the rubber damper 40 is provided on the outer periphery of this extended portion at a position separated from the lower end surface of the outer shaft 32 in the axial direction by a distance L _1. Fitted and fixed. When the outer shaft 32 descends, the lower end of the outer shaft 32 comes into contact with the rubber damper 40 and pushes the inner shaft 33 downward. Vacuum passage opening to the lower end surface of the inner shaft 33
Inside the lower end opening of 34, a suction nozzle 41 for sucking the chip component 14 is mounted, and this suction nozzle 41 is fitted through a coil spring 42 so as to be vertically movable in the axial direction, and When the thickness of the coil changes, the change in the thickness can be absorbed by compressing the coil spring.

On the outer circumference of the outer shaft 32, the inside of the cylinder 24 is located in the upper chamber 43.
A piston 45 that divides into a lower chamber 44 and a lower chamber 44 is attached. The upper chamber 43 and the lower chamber 44 are in communication with the air pumps 46, 46 via air supply passages 47, 47, respectively, and by supplying air to the upper chamber 43 or the lower chamber 44, the outer shaft together with the piston 45. 32 is lowered or raised. Therefore, the cylinder 24 and the piston 45 constitute the driving means for the outer shaft 32.

Further, two guide shafts 51, 51 for guiding the up-and-down movement of the inner shaft 33 are connected to the bracket 50 provided on the end cap 36. The guide shafts 51, 51 slidably pass through the vertical hole of the head main body 23 and the shaft portion 31.
Of the outer shaft 32, and one lower end thereof faces the pressing rod 20 of the feeding mechanism 16 when the suction head 22 is located at the suction position P ₂ .

The inner shaft 33 and the guide shafts 51, 51 are
It is urged upward through the return spring 52. An adjusting screw 53 for stroke adjustment is screwed into the lid member 26 through which the shaft part 31 penetrates.

The upper part of the adjusting screw 53 penetrates the bracket 50 in the vertical direction, and the adjusting screw 53 abuts on the upper surface and the lower surface of the bracket 50, and the inner shaft 33 and the guide shaft 51,
Stoppers 54 and 55 for restricting the stroke amount of 51 are attached. The stopper 55 that comes into contact with the lower surface of the bracket 50 is provided at a position separated from this lower surface by a distance L ₂ .
This distance L ₂ is set to be larger than the distance L ₁ between the lower end surface of the outer shaft 32 and the damper 40.

Therefore, when the lower end of the outer shaft 32 comes into contact with the damper 40 of the inner shaft 33, the outer shaft 32 is
The descent starts with 32. And this outer shaft
The stroke amount L of 32 and the piston 45 is L ₁ + L ₂ .

Further, the outer peripheral surfaces of the outer shaft 32 and the inner shaft 33 are flatly cut out in a portion penetrating the guide 30, and the rotation stop pins 57 which are in rolling contact with the flat end surfaces 32a, 33a of the both shafts 32, 33 are pivotally supported. ing. As a result, the guide 30, the outer shaft 32, and the inner shaft 33 are connected so as to be relatively slidable in the axial direction but not relatively rotatable in the rotational direction. Therefore, the three members rotate together.

A piston rod 63 of an air cylinder 62 is connected to the outer peripheral portion of the guide 30 via a joint 60, and the expansion and contraction of the piston rod 63 causes the guide 30, the outer shaft, and the like.
32 and inner shaft 33 are within a certain range (eg 90 degrees)
Are rotated together.

By the way, at the lower end of the guide 30, four correction arms 63a, 63b and 64a, 64b for positioning the chip component 14 sucked by the suction nozzle 41 are arranged at equal intervals in the circumferential direction. These correction arms 63a, 63b and 64a, 64b are a set of two diametrically opposed arms, the upper end of which enters the slit 65 ... It is supported via the guide 30 so as to be rotatable in the radial direction. And correction arms 63a, 63b, 64
A sandwiching piece 67 that sandwiches two opposite surfaces of the chip component 14 is fixed to the lower ends of the a and 64b, and a lever portion 68 that projects radially outward from the guide 30 is provided at the upper end thereof. Are integrally formed.

The modified arms 63a, 63b, 64a, 64b above are the shaft parts 31
It is arranged so as to surround the outside of the shaft part
A cam follower 69, which comes into contact with a conical cam 32b provided at the lower end of the outer shaft 32, is projectingly provided on the surfaces facing each other across 31. The cam follower 69 extends obliquely inward, and when the outer shaft 32 descends, the conical cam 32b pushes the cam follower 69 outward in the radial direction, and the correction arm
63a, 63b, 64a, 64b are expanded outward. By lowering the outer shaft, the correction arms 63a, 63b, 64a, 64b are opened outward, and then the cam follower 69 is provided more than the damper 40 provided at the lower end of the inner shaft 33 so that the suction nozzle 41 starts to descend. It is located above.

Further, a correction arm 63 is provided on the outer peripheral surface of the lower end portion of the guide 30.
A sleeve 70 for urging a, 63b, 64a, 64b in the closing direction is fitted slidably in the axial direction. The sleeve 70 is an inner sleeve 71 that interlocks the one pair of correction arms 63a and 63b.
And outer sleeve that interlocks the other correction arm 64a, 64b
It has a double structure with 72, and each sleeve 71, 72 is urged downward by a return spring 73 so that the lower end portion thereof abuts on the lever portion 68. In this case, the lower end of the inner sleeve 71 has a lever portion of the other pair of correction arms 64a and 64b.
A recess 74 is provided to avoid interference with 68, and a recess 75 is provided at the lower end of the outer sleeve 72 thereof for avoiding interference with the lever 68 of one of the correction arms 63a and 63b.
Is provided. Therefore, the correction arms 63a, 63b and 64a, 64b are biased in the closing direction independently by each group by the inner sleeve 71 and the outer sleeve 72.

A damper 80 is provided on each of the correction arms 63a, 63b, 64a, 64b so as to come into contact with the outer periphery of the lower end of the inner shaft 33 when the correction arms 63a, 63b, 64a, 64b are closed. , 63b, 64a, 64b are slidably mounted in the opening / closing direction, and the damper 80 absorbs and relaxes the shock when the holding piece 67 holds the chip component 14.

In such a configuration, when the suction head 22 stops at the suction position P ₂ due to the movement of the head support portion 8 in the XY directions, air is supplied to the upper chamber 43 through the air pump 46,
The piston 45 is pushed downward and the outer shaft 32 connected to the piston 45 starts to descend. At this time, since the inner shaft 33 is biased upward by the return spring 52, the inner shaft 33 and the outer shaft 32 do not descend integrally.

When the outer shaft 32 descends and its conical cam 32b contacts the cam follower 69 of each correction arm 63a, 63b, 64a, 64b, each correction arm 63a, 63b, 64a, 64b causes the sleeve 71, 72 to move.
They simultaneously open against the biasing force of the return spring 73 that presses. As shown in FIG. 8, in order to shorten the time required to mount the chip component, the timing at which the correction arm opens and leaves the chip component and the timing at which the suction nozzle starts to descend can be set to be substantially the same. ,
Further, by adjusting the timing of the lowering of the correction arm control means and the lowering of the suction nozzle appropriately in accordance with the largest chip component to be handled, all of the chip components to be handled have the suction nozzle after the correction arm is opened. It is possible to allow the chip component to be lowered after it has started to be lowered.

As shown in FIG. 8, when the lower end of the outer shaft 32 passes through the cam follower 69 and comes into contact with the damper 40, the inner shaft 33 and the guide shaft 51 follow the outer shaft 32 and start descending. By lowering this inner shaft 33,
The suction nozzle 41 projects from between the sandwiching pieces 67, and one guide shaft 51 pushes the pressing rod 20 to rotate the rickshaw 19 of the feed mechanism 16 by a certain angle.

Then, as shown in FIG. 7, when the inner shaft 33 descends to the lowest position and the suction nozzle 41 sucks the upper surface of the chip component 14, the upper chamber 43 is evacuated and the lower chamber 44 is pumped. Air is supplied from 46. As a result, the piston 45 receives an upward force and the outer shaft 32 starts to rise, which causes the inner shaft 33 to return to the return spring 52.
The chip component 14 is peeled off from the adhesive tape 13 by being pushed up by the urging force of.

Simultaneously with the rise of the inner shaft 33, the guide shaft 51 also rises, and the rickshaw 19 and the ratchet wheel 17 of the feed mechanism 16 are pulled back by the spring 21, so that the adhesive tape 13 is fed out,
The next chip component 14 is sent to the suction position P ₂ .

By the way, the correction arms 63a, 63b, 64a, 64b are constantly biased in the closing direction by the sleeves 71, 72, and their cam followers 69 are in contact with the outer peripheral surface of the lower end of the outer shaft 32. When the cam 32b rises to the position of the cam follower 69, the correction arms 63a, 63b, 64
The sandwiching pieces 67 of a and 64b sandwich the side surfaces of the chip component 14 sucked by the suction nozzle 41 from the directions orthogonal to each other. By this pinching, the position of the chip component 14 with respect to the suction nozzle 41 in the width direction and the longitudinal direction is adjusted, and the chip component is centered with respect to the suction nozzle.

Therefore, the outer shaft 32 causes the correction arms 63a, 63b, 64 to
This constitutes a correction arm control means for opening / closing a and 64b and moving up / down the inner shaft 33.

Next, the head support portion 8 again moves in the XY directions, the suction head 22 that has sucked the chip component 14 is stopped at a predetermined position on the printed circuit board 3 at the chip component mounting position P ₁ , and the suction nozzle is sucked by the air cylinder. 41 and correction arm
63a, 63b, 64a, 64b are integrally rotated within a predetermined range (for example, 90 degrees), and the mounting direction of the chip component 14 is selected. Subsequently, the lower chamber 44 is evacuated, and at the same time, the upper chamber 43 is exhausted.
When air is supplied to the shaft part 31 to start descending, the correction arms 63a, 63b, 64a, 64b start to open again, and then the suction nozzle 41 descends to adsorb the chip part 14 as shown in FIG. Is placed at a predetermined position on the printed circuit board 3. Then, the suction of the chip component 14 is released and the mounting on the printed circuit board 3 is completed.

Incidentally, reference numeral B in FIG. 7 indicates an adhesive for fixing the chip component 14.

As described above, the lifting operation of the outer shaft 32 can perform the opening / closing operation of the four correction arms 63a, 63b, 64a, 64b and the lifting operation of the inner shaft 33 having the suction nozzle 41. Adsorption of chip parts to 41,
The suction position of the chip component is corrected by raising and lowering the outer shaft 32 driven by the piston 45, and the suction head is remarkably different from the conventional technique in which the above two operations are performed by different actuators. It will be smaller and lighter.

From the above, the suction head 22 is in the chip mounting position.
The inertia of the suction head 22 when starting and stopping at P ₁ or the chip suction position P ₂ is small, and therefore its start,
The stopping operation is performed quickly, the positioning accuracy of the suction head 22 with respect to the chip component 14 on the adhesive tape or the printed circuit board 3 is improved, and the operating speed and work efficiency of the chip component mounting work can be significantly improved.

The shape of the chip component is not limited to a rectangular parallelepiped, and it may be circular or cylindrical, and the number of correction arms may be appropriately selected according to the shape of the chip and the usage of the chip component mounting apparatus. Is.

〔The invention's effect〕

As described above, since the chip component mounting apparatus of the present invention opens and closes the correction arm and raises and lowers the suction means by raising and lowering the correction arm control means, the opening and closing of the correction arm and the raising and lowering of the suction means are performed by the correction arm control means. This can be performed by one actuator for raising and lowering. Therefore, both the opening and closing of the correction arm and the raising and lowering of the suction means are performed by separate actuators, respectively, and the correction arm is dedicated via a special operating mechanism. The suction head can be remarkably reduced in size and weight as compared with the above-described conventional technique operated by an actuator. Further, the correction arm control means is a hollow cylindrical body provided outside the suction means and concentric with the suction means, and has a correction arm opening / closing operation section, and the correction arm opening / closing operation section directly applies the correction arm. Therefore, the drive mechanism of the correction arm by the drive means can be made extremely small and simple. Further, the driving means of the present invention is a suction means,
Instead of moving up and down the main members of the opening / closing mechanism such as the correction arm and the correction arm support, the drive means only moves up and down the correction arm control means and the suction means, the moving mass is small, and the weight of the drive means is small. Can be lightened. Therefore, the inertia of the suction head can be significantly reduced. Therefore, the start and stop operations of the suction head at a predetermined position can be speeded up, the operating speed can be increased, and the accuracy of the stop position can be significantly improved.

Further, there is known a device in which a single actuator is used to open and close the correction arm and raise and lower the suction nozzle (Japanese Utility Model Publication No. 52-20666). It is composed of a protrusion, a ratchet gear, and a ratchet pawl.The correction arm is held in an open state by the ratchet gear and the ratchet pawl, and the ratchet pawl is pushed up by the correction arm control means. Since it is for closing, the opening / closing drive mechanism of the correction arm is complicated and the suction head cannot be made lighter,
In order to place the sucked chip component on the substrate, the chip component sucked by the suction nozzle must be held by the correction arm and lowered against the gripping force. Since an unreasonable force acts on the chip component after the correction of, the position of the chip component is unavoidable. However, according to the present invention, since the opening / closing operation of the correction arm and the lifting operation of the suction means can be sequentially performed by a predetermined procedure by raising and lowering the correction arm control means, regardless of the size of the chip component to be handled, the correction arm is provided. After the gripping of the chip component by is completely released, the descent of the chip component can be started. therefore,
The above problems of the known ones are certainly avoided.

[Brief description of drawings]

1 is a sectional view of an embodiment, FIG. 2 is a side view of the suction nozzle of FIG. 1, FIG. 3 is an enlarged cross-sectional view of the suction nozzle and the correction arm of FIG. 1, and FIG. 4 is FIG. View IV, Figure 5,
FIG. 6 is a perspective view around the correction arm of FIG. 1, FIG. 6 is a sectional view taken along line VI-VI of FIG. 2, FIG. 7 is a sectional view of the suction nozzle in the most lowered state, and FIG. FIG. 9 is a plan view of the entire chip component mounting apparatus to which the present invention is applied, and FIG. 11 is a side view of FIG. 10. . 2 ... Conveyor (conveyance path), 3 ... Printed circuit board (board), 8 ... Head support part, 12 ... Component supply part, 14 ...
Chip parts, 22 …… Suction head, 24,25 …… Drive means (cylinder, piston), 30 …… Guide, 31 …… Shaft parts, 32 …… Outer shaft (correction arm control means),
32b: conical cam, 33: inner shaft, 41: suction nozzle (suction means), 63a, 63b, 64a, 64b: correction arm, 68: lever part, 69: cam follower, 70: sleeve.

Claims (1)

[Claims] 1. A component supply unit is movable between a component suction position for sucking a chip component and a component mounting position for mounting a component on a board. The chip component is sucked and sucked at the component suction position. In a chip component mounting apparatus having a suction head for mounting a chip component on a substrate at the component mounting position, the suction head includes a suction means at its lower end for moving up and down and suctioning the chip component. It is provided with at least one set of correction arms for sandwiching the sucked chip component to correct the position of the chip component with respect to the suction means, and further capable of moving up and down relative to the suction means and the correction arm. A correction arm control means for opening the correction arm by lowering it and closing the correction arm by raising it, and The correction arm control means is a hollow cylinder provided outside the suction means and concentric with the suction means, and the correction arm opening / closing operation cam portion is provided. The correction arm control means is lowered by a predetermined stroke with respect to the suction means and the correction arm to open the correction arm by the correction arm opening / closing operation cam portion, and then the correction arm control means pushes down the suction means. And raising the correction arm control means,
Following this rise, the suction means is raised to a predetermined position, and then only the correction arm control means is further raised to close the correction arm by the correction arm opening / closing operation cam portion.