JPH04147860A - Uniform squeegee pressure printer - Google Patents

Abstract

PURPOSE:To dispense with procedures for making squeegee pressure uniform and make the pressure adequately uniform by retaining the squeegee on a squeegee retaining part through an elastic device. CONSTITUTION:A pair of coil springs 37 which are an elastic device are installed facing downward at both ends of a squeegee retaining part 17 provided at the lower end of a rod 25, and squeegees 9, 11 are supported at the lower end of the coil spring 37. If the squeegees 9, 11 are afloat from a screen 3, pin 41 comes in contact with the upper end of a slit hole 39, and the squeegees 9, 11 are prevented from dropping off due to the weight of the squeegees 9, 11 and the elastic force of the coil spring 37. A distance between the squeegees 9, 11 which is afloat from the screen 3 is constant due to the length of the slit hole 39. A press-down action is generated by a press-down device. The press-down force is regulated to such an extent that the pin 41 comes to the center of the slit hole 39. Further, the squeegees 9, 11 are pressed under a constant pressure against the screen 3 to become airtight between these two component parts by a elastic force set previously at an elastic device consisting of coil spring 37.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a printing machine such as a cream solder printing machine that applies cream solder to a predetermined position on a printed wiring board by a printing method.

Conventional technology When mounting leadless electronic components such as chip parts on a printed wiring board, first apply cream solder made by mixing flux and fine print agent to a predetermined position on the printed wiring board. Apply accurately. This predetermined position corresponds to a terminal of an electronic component to be attached later. The electronic components are then adhesively attached in the determined locations.

Due to this adhesion, the terminal of the electronic component is placed in contact with the applied cream solder. Thereafter, the printed wiring board with the electronic components attached thereto is passed through a high temperature furnace for a certain period of time. During this passage, the cream solder melts and printing agent is applied to the terminal portion of the electronic component.

In the mounting process, the step of applying cream solder to a predetermined position on the printed wiring board is performed as shown in FIGS. 5 to 7. That is, the screen 3 is placed over the printed wiring board 1. A minute opening 5 is formed in this screen 3, and this minute opening 5 corresponds to a predetermined position on the printed wiring board 1 to which cream solder 7 is to be applied. Cream solder 7 is on screen 3
A lump of water is placed thereon and applied to the minute opening 5 using two squeegees 9 and 11. These two squeegees 9.1
1 are parallel and facing each other with a certain interval. A lump of the cream solder 7 is stored between the two squeegees 9 and 11. This squeegee 9.11 is reciprocated at right angles to the longitudinal direction. During this reciprocating movement, the front squeegee 9 in the moving direction floats up from the surface of the screen 3 by a gap G, and the rear squeegee 11 is pressed against the surface of the screen 3 by a constant pressure. By applying this pressure, the cream solder 7 is applied to the minute openings 5 of the screen 3, and is applied to a predetermined position on the printed wiring board 1.

This reciprocating movement is repeated, and the cream solder 7 is sequentially replenished as it is consumed.

FIG. 7 shows a reduction device for pressurizing the squeegee. The squeegee 9, 11 having a contact portion 15 at the lower end is held by a rotating shaft 19 with respect to a squeegee holding portion 17.
It is biased toward the center in a counterclockwise direction. A micrometer mechanism 21 is attached to one end of this squeegee 9.11, and this one end can be moved up and down. The amount of this vertical movement can be finely adjusted using a knob 23. A central rod 25 of the squeegee holding portion 17 is fixed to a piston 29 of a hydraulic cylinder 27. A spring 31 is provided between the lower side of the piston 29 and the inner wall of the hydraulic cylinder 27. The vertical position of this rod 25 can be adjusted using an adjustment screw 33.

With the above configuration, when the fluid 35 is supplied into the hydraulic cylinder 27, the piston 29 and the rod 25 are pushed down, and the contact portions 15 of the squeegees 9 and 11 pressurize the surface of the screen 3 with a predetermined pressure. Further, when the fluid 35 is discharged, the piston 29 and the rod 25 are pushed up by the action of the spring 31, and the contact portions 15 of the squeegees 9 and 11 float above the screen 3. This hydraulic cylinder 2
The pressure applied to the screen 3 by the squeegees 9 and 11 is kept constant by the amount of fluid supplied to the screen 7 and the action of the adjusting screw 33. Further, by moving one end of the squeegee 9, 11 up and down using the micrometer mechanism 21, fine adjustment can be made so that the contact portion 15 of the squeegee 9, 11 is parallel to the surface of the screen 3. By finely adjusting this parallelism, the pressure applied by the contact portion 15 of the squeegee 9.11 to the screen 3 can be adjusted to the pressure applied to the screen 3 by the squeegee 9.11.
11 can be made uniform in the longitudinal direction.

Problems to be Solved by the Invention However, in the conventional printing press described above, it was difficult to adjust the parallelism of the squeegees 9 and 11 to make the pressure uniform. That is, in order to make the pressure uniform, the stroke of the piston 29 is adjusted using the adjusting screw 33 to obtain an appropriate pressure, and the knob 23 of the micrometer mechanism 21 is rotated to slightly tilt the squeegee 9, 11. Adjustments must be made, and much of the work depends on the intuition of the operator, making the work time-consuming and evening the pressure itself is insufficient. Furthermore, the micrometer mechanism 21 is expensive, and the mechanism for holding the micrometer mechanism 21 is also complicated, which increases the cost and weight of the entire printing press.

The present invention solves these conventional problems, and eliminates the micrometer mechanism, reduces cost and weight, and eliminates the need for work to equalize the pressure of the squeegee. It does not require much effort and the pressure can be made sufficiently uniform. The object of the present invention is to provide a printing machine with uniform squeegee pressure.

Means for Solving the Problems In order to achieve the above-mentioned object, the first invention provides a method for placing a printing agent on a screen and applying pressure to the screen with a squeegee held in a squeegee holding part of a reduction device. In a printing press that performs printing by moving back and forth, the squeegee is held by a squeegee holding section via an elastic device.

Further, in a second aspect of the invention, the elastic device is provided with an adjusting means for adjusting the elastic force.

Therefore, without having to make fine adjustments to the reduction amount of the reduction device or the parallelism of the squeegee, the elastic device can absorb these fine adjustments. Therefore, the pressure of the squeegee can be made uniform along the length of the squeegee without adjusting the piston stroke of the hydraulic cylinder using an adjustment screw or finely adjusting the parallelism of the squeegee using a micrometer mechanism as in the past. It becomes possible to do so.

EXAMPLE An example of the present invention is shown in FIGS. 1 to 3. FIG. 1 is a front view of the squeegee, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a diagram showing the squeegee in FIG. 1 in a floating state.

A pair of coil springs 37, which are elastic devices, are attached downward to both ends of the squeegee holding portion 17 provided at the lower end of the rod 25.
, 11 are supported.

Further, between the pair of coil springs 37, elongated holes 39 that are long in the vertical direction are provided at two locations in the width direction of the squeegee 9.11.
is formed. A pin 41 protruding from the squeegee holding portion 17 passes through the elongated hole 39 and is movable up and down. The length of this elongated hole 39 is such that it can absorb errors or variations in the amount of reduction by a reduction device (not shown). Furthermore, this reduction is not carried out at all;
As shown in FIG. 3, when the squeegees 9 and 11 are floating, the length and elastic modulus of the coil spring 37 and the length of the elongated hole 39 are adjusted so that the pin 41 comes into contact with the upper end of the elongated hole 39.
The length is set.

Next, the operation of the above embodiment will be explained. As shown in FIG. 3, when the squeegee 9, 11 is not in the printing operation and is floating above the screen 3, the pin 41 comes into contact with the upper end of the elongated hole 39, causing the squeegee 9, 11 to move. The squeegee 9, 11 is prevented from falling downward by its own weight and the elastic force of the coil spring 37. Further, depending on the length of this elongated hole 39, the distance from the screen 3 of the squeegee 9.11 in the floating state is constant. Next, the first
As shown in FIGS. and 2, rolling down is performed by a rolling down device (not shown). At this time, the amount of reduction is such that the pin 41 is located approximately at the vertical center of the elongated hole 39. Depending on this reduction amount and the elastic force of the coil spring 37, that is, the elastic modulus of the coil spring 37, the length of the spring, etc.
1 is designed to pressurize the screen 3 with a predetermined pressure.

As described above, according to the above embodiment, when the rolling down device (not shown) performs rolling down, the rolling down amount is such that the pin 41 is located in the center of the elongated hole 39, and the coil spring 37
Due to the predetermined elastic force of the elastic device, the squeegee 9.11 is pressed against the screen 3 with a constant pressure and brought into close contact with the screen 3. In other words, even if the amount of reduction by the reduction device is not strictly adjusted as in the conventional case, the unadjusted amount is absorbed by the coil spring 37, and the pressure is always maintained at a constant level even if there are irregularities on the surface of the screen 3. pressure is applied.

Furthermore, since the pair of coil springs 37 are provided in the longitudinal direction of the squeegee 9, 11, this fine adjustment can be made without having to strictly finely adjust the parallelism of the squeegee 9, 11 as in the conventional case. The coil spring 37 absorbs the pressure and can maintain uniform pressure in the longitudinal direction of the squeegees 9 and 11. Therefore, a conventional micrometer mechanism for finely adjusting the parallelism of the squeegee 9.11 is not required, and the cost and weight of the entire printing press can be reduced.

A second embodiment of the invention is shown in FIG. In this embodiment, a coil spring 37 constituting an elastic device is provided with an adjusting screw 43 as an adjusting means for adjusting the elastic force. That is,
By rotating the adjusting screw 43 provided on the squeegee holding part 17, the tip of the adjusting screw 43 is aligned with the coil spring 3.
7 to adjust the overall length of the coil spring 37.

This makes it easy to apply the present invention to variations in printing conditions, such as when printing is performed with different elastic forces of the left and right coil springs 37, or to variations in the spring performance of the coil springs 37.

In addition, in the above two embodiments, a pair of coil springs 37 provided at both longitudinal ends of the squeegee 9.11 were explained as an example of the elastic device, but in other embodiments, three or more coil springs 37 may be provided. It is also possible to use another leaf spring or the like instead of the coil spring 37. Furthermore, instead of a spring, an elastic device using another air cylinder or the like may be used.

Although the above embodiments have been described using a cream solder printing machine as an example of a printing machine, the present invention is not limited to the cream solder printing machine, but can be implemented in other printing machines that perform printing operations using a squeegee. For example, a non-printed material such as paper or plastic may be used instead of a printed wiring board, an aperture for forming a printed pattern as a screen, and a medium-viscosity printing agent instead of cream solder. Further, in the embodiment, the printing operation is performed using two squeegees, but the printing operation may be performed using only one squeegee. That is, the squeegee moves in one direction, floats once, and then moves in the same direction again in the floated state to overcome the lump of printing material. Thereafter, it descends and is pressed onto the screen, and moves in the opposite direction, allowing a single squeegee to perform a printing operation.

Effects of the Invention As is clear from the above examples, the present invention has the following effects.

(1) In the first invention, the elastic device absorbs the unadjusted amount without having to make fine adjustments to the reduction amount of the reduction device or the parallelism of the squeegee, so there is no need to work to equalize the pressure of the squeegee. The squeegee pressure can be made sufficiently uniform without requiring much time or effort. Furthermore, since there is no need to finely adjust the parallelism of the squeegee, a micrometer mechanism necessary for this fine adjustment can be provided, and the cost and weight of the printing press as a whole can be reduced.

(2) In the second invention, by further adjusting the elastic force of the elastic device, it is possible to respond more flexibly to variations in printing conditions.

[Brief explanation of drawings]

Fig. 1 is a front view showing the squeegee portion of a squeegee pressure uniform printing machine showing an embodiment of the present invention, Fig. 2 is a side view of Fig. 1, and Fig. 3 is a state in which the squeegee shown in Fig. 1 is floating. FIG. 4 is a front view showing a second embodiment of the present invention, and FIG. 5 is a side view of the squeegee portion of a printing press having a conventional squeegee. 6 is a schematic plan view of FIG. 5, and FIG. 7 is a front view showing the pressurizing device for the squeegee shown in FIG. 5. DESCRIPTION OF SYMBOLS 1... Printed wiring board, 3... Screen, 4... Micro opening, 7... Cream solder, 9.11... Squeegee, 17... Squeegee holding part, 19... Rotation Shaft, 21... Micrometer mechanism, 23... Knob,
25...Rod, 27...Hydraulic cylinder, 29...
・Piston, 31... Spring, 33... Adjustment screw, 3
7... Coil spring (elastic device), 39... Long hole, 4
1... Pin, 43... Adjustment screw (adjustment means). Name of agent: Patent attorney Akira Koeji, et al. 22 Figures Figures Figures Figures! Diagram

Claims (2)

[Claims] (1) In a printing machine that prints by placing a printing agent on a screen and pressing a squeegee held in a squeegee holding part of a reduction device against the screen and moving it back and forth, the squeegee is moved through an elastic device to the squeegee. Squeegee pressure uniform printing machine held in a holding unit. (2) The squeegee pressure uniform printing machine according to claim (1), wherein the elastic device is provided with an adjusting means for adjusting the elastic force.