JPH02230789A - Squeegee apparatus for screen printing machine - Google Patents

Abstract

PURPOSE:To realize a squeegee apparatus for a screen printing machine which is excellent in following-up property to fine unevenness on a substrate by using an elevating means capable of expanding by supplying gas to the inside of a bellows-type cylinder. CONSTITUTION:At the time of printing, gas at a specified pressure is supplied to a contraction and expansion body 13 by a compressor 19, and said body 13 is expanded by a dimension C; then a stepping motor is driven, and an elevating block 15 is made to descend by a ball screw 17; a screen 4 is pressed down by a squeegee tip 5a; said squeegee tip descends by a dimension D to come into contact with the upper surface of a substrate 2 at a specified pressing-down pressure; then the squeegee is stopped by a brake 28 and maintains the state. In this state, on account of the elasticity of gas in the contraction and expansion body 13, the above dimension C becomes C'; the squeegee tip 5a descends by a dimension D', and comes into contact with the substrate 2 via a screen 4; thus a specified pressing-down pressure is applied. During printing, the squeegee tip 5a repeats fine up-and-down motion in accordance with unevenness of the substrate 2 surface, but the contraction and expansion body 13 absorbs the up-and-down motion.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a squeegee device for a screen printing machine, and in particular, to a squeegee device that allows the squeegee to closely follow minute irregularities on the surface of a substrate when printing fine electronic circuits. This article relates to a squeegee device for screen printing machines that enables printing with a uniform film thickness and prevents the occurrence of scratches and blurring in the printing. [Prior Art] As described in Japanese Unexamined Patent Application Publication No. 53-61419, a conventional device is constructed by dividing a squeegee into a plurality of blocks, and only the blocks that hit the protrusions on the surface of the substrate escape. ，
The other blocks were designed to slide closely together on the screen. The squeegee is raised and lowered using an air cylinder, hydraulic cylinder, or electric power. In addition,
An example of this type of device using a cam and cross-shaft gears is JP-A No. 57-201658. (Problems to be Solved by the Invention) In the above prior art, when a fine electronic circuit is printed on a substrate, the squeegee tip escapes from the unevenness of the substrate or minute unevenness due to the printed circuit due to the elasticity of the material constituting the squeegee. This is done by deforming or raising and lowering the squeegee with sliding resistance of the piston inside the cylinder. In either case, the downward pressure at the tip of the squeegee fluctuates locally and does not follow the unevenness of the substrate, resulting in uneven film pressure of the printed ink. In addition, the guide for raising and lowering the squeegee is attached to the squeegee boulder, and when the squeegee goes up and down, the guide also goes up and down, which increases the mass of the squeegee to move up and down, further worsening the ability to follow the unevenness described above. Furthermore, since the guide moves up and down, it was not possible to improve the precision of the guide's guidance, and it was not possible to improve the printing precision. Since the lifting speed of the squeegee is not controlled to obtain at least a low speed, when the squeegee rises, the downward pressure of the squeegee suddenly disappears, and the screen shakes due to the elasticity of the tension, causing ink to scatter. There was a problem in that contact between the screen and the printed substrate caused unnecessary ink adhesion, so-called whiskers, and blurring. An object of the present invention is to provide a squeegee device for a screen printing machine that can follow minute irregularities on a substrate without changing the pressing pressure of the squeegee and obtain a uniform printed film thickness. Another object of the present invention is to provide a squeegee device for a screen printing machine that can prevent unnecessary ink adhesion and the occurrence of scratches and scratches. [Means for Solving the Problems] In order to achieve the above object, the first elevating means is a bellows-shaped cylindrical body that expands and contracts by supplying or discharging gas inside it, and the second elevating means is a stem. Consisting of a ping motor and a ball screw, the lifting block can be raised and lowered,
A first elevating means is arranged on the elevating block, a squeegee boulder is connected to the tip of the extensible body of the first elevating means with a spherical joint, a guide for guiding the elevating block and the squeegee holder is fixed to the upper frame, and the squeegee The holder is guided by a straight cross roller guide provided on the guide, and the holder is guided by a straight cross roller guide provided on the guide, and the holder can be raised at a low speed until the moment the squeegee rises after printing and leaves the surface of the screen. Discharge while adjusting the discharge with a control valve, or
Or drive the stepping motor at low speed. [Function] The extensible body of the first elevating means consists of a bellows-shaped cylindrical body, so it expands by supplying gas to the inside of the cylindrical body.
During printing, when the squeegee slides through the screen over a surface with minute irregularities due to the unevenness of the substrate or the printed circuit, the bellows-shaped cylinder does not cause fluctuations in the internal gas pressure. The squeegee can expand or contract without any resistance, so the squeegee follows the unevenness of the board with even downward pressure. The squeegee holder that holds the squeegee has a structure in which it is guided by a straight cross roller guide provided on a holder guide fixed to the frame installed at the top, so the squeegee can move up and down while following the unevenness of the board. The squeegee holder is small and the sliding resistance during lifting and lowering is extremely small, and since it is guided from the frame, the squeegee holder can be guided with precision. In the ascending section until the squeegee leaves the surface of the screen after printing, the internal gas of the expandable body of the first elevating means can be discharged while being controlled by the control valve.
The squeegee rises at low speed to prevent screen shake. Furthermore, since a stepping motor is used to drive the second elevating means up and down, it can be easily driven at low speed, and screen shake can be prevented. [
Example] An example of the present invention will be described below. Figure 1 is a front view of the squeegee device.
A screen 4 is attached to the plate frame 3 with a predetermined tension and is spaced apart from the substrate 2 by a distance A. The tip 5a of the squeegee 5 is placed at a distance B from the screen 4. The squeegee attachment part 6 fixes the squeegee 5 with a plurality of bolts 7, and its central portion is pivotally held by a squeegee holder 9 with a pin 8.

Both ends 6a and 6b of the squeegee attachment portion 6 are adjusted and held by adjustment bolts 10 provided at the side ends 9a and 9b of the squeegee holder 9 to a position where the substrate 2 and the squeegee tip 5a are parallel. At the center of the squeegee holder 9 is a spherical joint 1.
1 is fitted, the spherical joint 11 is screwed to the lower end 13a of the elastic body 13 of the first elevating means 12, and the squeegee holder 9
Both sides 9c and 9d are guided by a holder guide 14 which is a linear cross roller guide. The upper end 13b of the extensible body 13 is screwed and fixed to the lifting block 15, both sides 15a and 15b of the lifting block 150 are guided by a block guide 16, and the central part of the lifting block 15 has a female thread 15c into which the ball screw 17 is fitted. is fixed. The holder guide 14 and the block guide 16 are the guide plate 1
8, and the guide plate 18 is screwed to a frame 22 on which a pneumatic device 19 for supplying gas to the first elevating means 12 and a drive device 21 for the second elevating means 20 are disposed. The holder guide 14 and the block guide 16 may be integrated into a guide 14' (see FIG. 3). The pressure air system i119 consists of a pressure air section 19a, a regulating valve section 19b, an exhaust section 19c, and a pipe 19d, and the pipe 19d is connected to the upper end of the expandable body 13 via a flexible hose 19d' and a lifting block 15. The drive device 21 of the second elevating means 20 includes a stepping motor 23 and a gear transmission 2.
4 and a brake 28, which drives the ball screw 17. FIG. 2 is a side view of the squeegee device, in which the frame 22 is guided by a rail 27 via a rod 25 and a squeegee sliding cylinder 26 to move. For printing, the compressed air device 19 supplies gas at a predetermined pressure to extend the expandable body 13 by a dimension C, and then the stepping motor 23 is driven to lower the lifting block 15 using the ball screw 17.
The squeegee tip 5a lowers the screen 4 by a distance D such that it contacts the upper surface of the substrate 2 with a predetermined pressing pressure, and is stopped and held by the brake 28. In this state, due to the elasticity of the gas in the expandable body 13, the above-mentioned dimension C becomes a dimension C', and the squeegee tip 5a descends by a dimension D' and presses the substrate 2 through the screen 4, applying a predetermined downward pressure. Then, the squeegee sliding cylinder 26 is extended and the squeegee 5 is moved in the direction of arrow E to perform printing. During printing, the squeegee tip 5a follows the unevenness of the surface of the substrate 2 and repeats minute movements up and down, but during this up and down movement, the extensible body 13 has a bellows-like shape, so the sliding movement between a cylinder and a piston is avoided. There is nothing equivalent to a dynamic resistance pile, and the expansion and contraction is without resistance and without fluctuations in gas pressure, and therefore the downward pressure of the squeegee tip 5a does not fluctuate either. Further, the lifting and lowering of the squeegee boulder 9 is guided by a holder guide 14 consisting of a linear cross roller guide with extremely small sliding resistance piles, and the mass of the holder guide 14 on the guiding side is equal to the frame 2.
2, it is a strong attachment that maintains accuracy, and the mass of the squeegee holder 9 that moves up and down can be reduced, improving the ability of the squeegee tip 5a to follow irregularities on the substrate 2 and reducing the downward pressure. Equalization is possible. The squeegee tip 5a is sliding on the screen 4! When the detector 29 detects that the printing end point of tF has been reached and the extension of the squeegee sliding cylinder 26 is stopped, the control valve part 19b enters the exhaust state, slowly exhausting the gas inside the expandable body 13, and the squeegee The tip 5a rises over a section of dimension G, and then opens the exhaust section 19c and is rapidly raised by the second elevating means 20. Since the squeegee tip 5a rises slowly until the moment it separates from the screen 4, the screen 4 does not shake due to the elasticity of the tension. To raise the section of dimension G, the stepping motor 23 of the second elevating means 20 may be driven at a low speed. ．． [Effects of the Invention] According to the present invention, the lifting and lowering of the squeegee that follows the irregularities on the substrate can be carried out without any fluctuation in the pressing pressure of the tip of the squeegee because the mass of the lifting part is small, the lifting resistance is extremely small. This makes it possible, and the thickness of the printed ink film becomes uniform. In addition, since the return of the screen after printing is completed is slowly raised, the screen does not shake, and it is possible to prevent the printed ink from becoming smudged or blurred. Furthermore, since there is no fluctuation in the downward pressure at the tip of the squeegee,
No impact occurs between the screen and the squeegee tip,
Longer life is achieved. As for the guide of the squeegee, it can be firmly fixed by fixing it to the upper frame, so it is highly accurate, has little play during operation, and can maintain accuracy for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a front view of one embodiment of the present invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a front view of the holder guide and block guide of FIG. 1 integrated. 1...Table, 2...Substrate, 3...Print frame, 4...
...Screen, 5...Squeegee, 8...Bin, 9
... Squeegee holder, 11... Spherical joint, 12...
- First elevating means, 13... Expandable body, 14... Holder guide, 15... Elevating block, 16... Block guide, 17... Ball screw, 18... Guide plate,
19... Pressure device, 20... Second lifting means, 21.
... Drive device, 22 ... Frame, 23 ... Stepping motor, 24 ... Gear transmission, 25 ... Rod, 26 ... Squeegee sliding cylinder, z2 ... Frame z3...B L-i

Claims (1)

[Claims] 1. A squeegee device for a screen printing machine that prints electronic circuits on a board includes a squeegee holder for holding a squeegee, a first elevating means for elevating and lowering the squeegee holder, a second elevating means for elevating and lowering the first elevating means, and a squeegee holder for elevating and lowering the squeegee holder. It consists of a holder guide that guides the lifting and lowering and a block guide that guides the lifting block that supports the first lifting means, and at least the first lifting means is made of an elastic body having a material shape that can be expanded and contracted without any expansion and contraction resistance. A squeegee device for screen printing machines featuring: