JPH05162285A - Screen printing machine - Google Patents

Abstract

(57) [Summary] [Purpose] At least one of the viscosity and the temperature of a printing medium such as a paste can be adjusted in real time during printing, and accurate printing is always performed. [Structure] A torque sensor 51 is provided coaxially with the roller 12, and a motor 14 for rotatably driving the roller 12 is provided via a motor drive circuit 55 so that the viscosity of the paste 31 detected by the torque sensor 51 becomes equal to a set value. Control the number of rotations. Further, a heater 62 is provided on the scraper 13, a temperature sensor 63 is provided in the paste 31, and the temperature of the paste 31 is made equal to a set value by a temperature adjusting section 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing machine, and more particularly to a screen printing machine for printing a solder paste as a printing medium on a printed circuit board.

[0002]

2. Description of the Related Art In a conventional screen printer, as shown in FIG. 5, a squeeze 2 attached to a lower end of a holder 1 is moved in a direction of an arrow A to roll a paste 4 supplied on a screen 3. , Screen 3
The paste 4 was pressed into the opening 5 and transferred onto the land 7 formed on the substrate 6 for printing. The paste 4 remaining on the screen 3 after printing was scraped off by moving the squeeze 2 in the direction of arrow A.

However, according to the above-mentioned conventional screen printing machine, the rolling and scraping of the paste 4 can be performed in one step.
It was done with two squeeze two. Therefore, the scraping speed must be increased in order to accelerate the rolling, and the scraping speed must be decreased in order to reduce the rolling. For this reason, it was not possible to increase the rolling speed required for paste printing on the high-density mounting substrate and to operate the scraping speed at a low speed.

In order to solve this problem, the present applicant has proposed a screen printing machine as shown in FIGS. 6 to 13 in Japanese Patent Application No. 91-292361.

6 to 12 show the configuration of an embodiment of the present proposal. As shown in FIG. 6, the screen printer 11 includes a roller 12, which is a rotating body, a scraper 13, and a motor 1.
4, a gear box 15 and a support body 16. As shown in FIGS. 7 and 8, a plurality of blades 17 are radially planted on the outer periphery of the roller 12 in parallel to the axial direction, and a rotary shaft 18 is concentrically provided at both ends so as to project. There is. The scraper 13 is formed in a substantially prismatic shape as shown in FIG. 9, and has a blade portion 13a on the lower surface. Further, a bifurcated mounting portion 13a is provided on the upper surface so as to project.

As shown in FIGS. 10 and 11, the motor 14 is attached to one end of the upper surface of the scraper 13, and a gear box 15 is attached to the side surface of the scraper 13 on the side where the motor 14 is attached. On the side of the scraper 13 opposite to the gearbox 15,
A bearing box 19 having the same shape as the gear box 15 is provided. The rotary shaft 18 of the roller 12 is rotatably supported by the gear box 15 and the bearing box 19. In addition, the output shaft 20 of the motor 14 has a drive side gear 21
Is fixed, and the driven gear 22 is fixed to the rotary shaft 18. Further, the gears 21 and 22 are the gearbox 1
It is housed in 5 and meshes with the intermediate gear 23.

On the other hand, the supporting body 16 shown in FIG. 6 is composed of a pair of bars 24 for holding the mounting portion 13b of the scraper 13, and a screw rod 25 inserted through the center in the longitudinal direction.
Is fitted to the center of the attachment portion 13b of the scraper 13 and is tightened, so that the support 16 and the scraper 13 can be integrally fixed.

In the above structure, the motor 1 shown in FIG.
When the roller 12 is rotatably driven by the roller 4, the blade 17 provided on the roller 12 is transferred to the paste 3 as shown in FIG.
1 is stirred, and the paste 31 is adjusted to a desired viscosity by the rotation of the roller 12. Then, it is printed on the land 35 formed on the substrate 34 through the opening 33 of the screen 32. Further, by moving the scraper 13 at a desired speed in the direction indicated by the arrow A, the unnecessary paste 31 remaining on the screen 32 is scraped off and the paste 31 is moved at a desired speed.

Incidentally, as shown in FIG. 13, there is also one in which two scrapers 13A and 13B are integrated and the scraper 13 is provided with a paste supply port 41. By doing so, the waste of the paste 31 is eliminated.

[0010]

However, in the screen printing machine configured as described above, in order to set the viscosity of the paste 31 to a predetermined value, the roller 1 is previously prepared.
It was necessary to measure the relationship between the rotational speed of 2 and the viscosity, and to rotate the motor 14 at the rotational speed corresponding to the viscosity of a predetermined value. Even if the rotation speed of the motor 14 is a predetermined value, the viscosity of the paste 31 changes as the temperature of the paste 31 changes, but the conventional screen printing machine cannot adjust the temperature of the paste 31 during printing.

The present invention has been made in view of the above circumstances, and at least one of the viscosity and the temperature of the printing medium can be adjusted in real time during printing, and printing can be performed with high accuracy at all times. It is an object of the present invention to provide a screen printing machine capable of performing the printing.

[0012]

According to a first aspect of the present invention, there is provided a screen printing machine including a roller 1 as a rotating body for rolling a paste 31 as a printing medium on a screen 32.
2. A screen printing machine having a motor 14 for rotating the roller 12, and a torque sensor 51 provided coaxially with the roller 12 as torque detecting means for detecting the torque of the paste 31 to be rolled. A motor drive circuit 55 as a control means that compares the detected value of the torque detected by the torque sensor 51 with a set value and controls the rotation speed of the motor 14 so that the detected value and the set value are equal.
And is provided.

A screen printing machine according to a second aspect is a screen printing machine having a roller 12 for rolling the paste 31 on the screen 32 and a scraper 13 for scraping off the paste 31 remaining on the screen 32 after printing. And the paste 3 is attached to at least one of the roller 12 and the scraper 13, respectively.
Temperature sensor 6 as temperature detecting means for detecting the temperature of 1
3 and a heater 62 as a heating means for heating the paste 31 and a detected value of the temperature of the paste 31 detected by the temperature sensor 63 are compared with a set value, and the heater 62 is controlled so that the detected value becomes equal to the set value. A temperature adjusting unit 64 as a control means is provided.

In the screen printing machine according to the third aspect, the rotational speed of the torque sensor 51 for detecting the torque of the paste 31 and the motor 14 for rotationally driving the roller 12 so that the detected torque value becomes equal to the set value. A motor drive circuit 55 for controlling, a temperature sensor 63 for detecting the temperature of the paste 31, a heater 62 for heating the paste 31, and a temperature control section 64 for controlling the heater 62 so that the detected temperature value becomes equal to a set value. Is provided.

[0015]

In the screen printing machine according to the first aspect, the viscosity of the paste 31 can be measured in real time during printing by using the torque sensor 51, and the motor drive circuit 55 controls the rotation speed of the roller 12. As a result, the viscosity of the paste 31 can be made equal to the set value.

In the screen printing machine according to the second aspect, the temperature of the paste 31 can be measured in real time during printing by using the temperature sensor 63, and the heater 62 is controlled by the temperature adjusting section 64. The temperature of the paste 31 can be made equal to the set value.

A screen printing machine according to a third aspect has the functions according to the first and second aspects,
Since the viscosity is measured while the temperature of the paste 31 is made equal to the set value and the number of rotations of the roller 12 is controlled, the viscosity can be accurately adjusted.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the screen printing machine of the first invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 show the structure of the essential parts of an embodiment of the first invention. In these figures, portions corresponding to those of the conventional example shown in FIG.
The description is omitted as appropriate. The feature of this embodiment is that the roller 1
2 is rotated and the viscosity of the paste 31 that is rolled by the blade 17 is measured and adjusted in real time using the torque sensor 51, and the configuration and operation of the screen printing machine main body are shown in FIGS. 6 to 12. Similar to the example.

1 and 2, the bearing box 19
A torque sensor 51 is provided outside the rotary shaft 18 of the roller 12.
It is mounted concentrically with. The detecting portion 52 of the torque sensor 51 includes the rotating shaft 1 inside the bearing box 19.
It is arranged so as to surround the outer circumference of 8, and is formed in a cylindrical shape. Further, a spiral groove 53 is provided on the outer periphery of the detection unit 52, and the paste 31 rolled by the rotation of the blade 17 slides up in the spiral groove 53, so that a rotation torque is generated in the detection unit 52. ing. The torque sensor 51 detects this rotational torque and the viscosity of the paste 31 is measured. The rotating shaft 18 is rotatably supported at the center of a connecting shaft 54 that connects the torque sensor 51 and the detecting portion 52 via a bearing (not shown).

The torque sensor 51 is connected to a motor drive circuit 55 for controlling the rotation speed of the motor 14, and the torque signal detected by the torque sensor 51 is input. In addition, the paste 3 required to make the paste 31 have a predetermined viscosity
The torque of 1 is preset, and the motor drive circuit 55
Controls the rotation speed of the motor 14 so that the torque setting value and the torque detection value become equal.

According to this embodiment, the viscosity is measured by detecting the torque generated by the paste 31 in real time during paste printing, and the rotational speed of the motor 14 is controlled so that the detected torque value is always the torque setting value. Therefore, the viscosity of the paste 31 can always be kept constant.

Next, an embodiment of the screen printing machine of the second invention will be described with reference to the drawings.

FIG. 3 and FIG. 4 show the construction of the essential parts of an embodiment of the second invention. In these figures, parts corresponding to those of the conventional example shown in FIG. 13 are designated by the same reference numerals, and the description thereof will be omitted as appropriate. The feature of this embodiment is that the roller 12 rotates and the temperature of the paste 31 rolled by the blade 17 is measured and adjusted in real time, and the configuration of the screen printing machine main body is the same as the conventional example shown in FIG. is there.

In FIGS. 3 and 4, holes 61 are formed in the portions 13A and 13B on both sides of the scraper 13 in parallel to the axial direction, and heaters 62 are inserted in the holes 61, respectively. .. A temperature sensor 63 is provided inside the lower end of the scraper 13 and at the lower end of the paste supply port 41. The heater 62 and the temperature sensor 63 are respectively connected to the temperature adjusting section 64, and the heater 62 is turned on and off so that the temperature detected by the temperature sensor 63 is always the set temperature.

According to this embodiment, the temperature of the scraper 13 is adjusted so that it is always constant, and the temperature of the paste 31 in contact with the scraper 13 is also substantially constant. It should be noted that the mounting position of the temperature sensor 63 should be as close to the outlet of the paste 31 as possible. Furthermore, since the paste 31 is constantly circulated in the scraper 13 by constantly rotating the roller 12, it is possible to prevent an abnormal temperature rise of only the paste 31 in the portion in contact with the scraper 13. In addition, the time required for the entire paste to reach the set temperature can be shortened. Here, the actual set temperature is preferably 20 ° C. to 30 ° C., and the scraper 13 is preferably made of a metal having a high thermal conductivity.
Further, the positions and the numbers of the heaters 62 and the temperature sensors 63, and the shape of the blade 13 are not limited to those shown in this embodiment. The print medium is not limited to the paste 31.

Since the viscosity of the paste 13 greatly changes depending on the temperature, the torque sensor 51, the motor drive circuit 55, the heater 62, the temperature sensor 63, and the temperature adjusting section 64, which are the constituent elements shown in the above-mentioned respective embodiments, are screened. It is advisable to attach all of them to a printing machine, detect the viscosity (torque) while adjusting the temperature of the paste 31 to a constant value, and adjust the rotation speed of the motor 14 based on the detection result.

[0028]

As described above, according to the screen printing machine of the first aspect, the rotating body is rotated so that the torque of the printing medium during printing is detected and the value becomes equal to the set value. Since the rotational speed of the driving motor is controlled, the viscosity can be adjusted in real time during printing.

According to the screen printing machine of the second aspect, the temperature of the print medium is detected during printing, and the heater is used to heat the temperature so that the temperature becomes a set value.
The temperature of the print medium can be kept constant in real time.

Further, according to the screen printing machine of the third aspect, since the temperature of the printing medium during printing is always kept constant in real time, the viscosity is also kept constant.
Stable printing can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a main part of an embodiment of a first invention of a screen printing machine of the present invention.

FIG. 2 is an exploded explanatory view of FIG.

FIG. 3 is an explanatory diagram showing a configuration of a main part of an embodiment of a second invention of the screen printing machine of the present invention.

FIG. 4 is an exploded perspective explanatory view of FIG.

FIG. 5 is an explanatory diagram showing an operation of a squeeze provided in an example of a conventional screen printing machine.

FIG. 6 is a perspective view showing a configuration of a main part of another example of a conventional screen printing machine.

FIG. 7 is a perspective view showing the roller of FIG.

FIG. 8 is a side view of FIG.

9 is a perspective view showing the scraper of FIG. 6. FIG.

10 is a side view showing the gear box of FIG. 6. FIG.

11 is a front view of FIG.

FIG. 12 is an explanatory diagram showing an operation of the conventional example shown in FIG.

FIG. 13 is an explanatory diagram showing the operation of a scraper according to another example of a conventional screen printing machine.

[Explanation of symbols]

 11 Screen Printer 12 Roller (Rotator) 13 Scraper 14 Motor 31 Paste (Printing Medium) 32 Screen 51 Torque Sensor (Torque Detecting Means) 55 Motor Drive Circuit (Control Means) 62 Heater (Heating Means) 63 Temperature Sensor (Temperature Detecting) Means) 64 temperature control unit (control means)

Claims (3)

[Claims] 1. A screen printing machine comprising: a rotating body that rolls a print medium on a screen; and a motor that rotationally drives the rotating body, the printing being provided coaxially with the rotating body and rolling. A control for comparing the detected value of the torque detected by the torque detecting means with the torque detecting means for detecting the torque of the medium with a set value, and controlling the rotation speed of the motor so that the detected value becomes equal to the set value. A screen printing machine characterized in that it is provided with means. 2. A screen printing machine comprising: a rotating body that rolls a print medium on a screen; and a scraper that scrapes off the print medium remaining on the screen after printing, wherein the rotating body and the scraper are small. And a heating means for heating the print medium and a temperature detection means for detecting the temperature of the print medium, respectively, attached to either one of them, and a detected value of the temperature of the print medium detected by the temperature detection means as a set value In comparison, the screen printing machine is provided with a control means for controlling the heating means so that the detected value becomes equal to the set value. 3. A torque detecting means for detecting a torque of a print medium, a control means for controlling a rotational speed of a motor for rotationally driving a rotating body so that the detected torque value becomes equal to a set value, and a temperature of the print medium. 3. A temperature detecting means for detecting the temperature, a heating means for heating the print medium, and a control means for controlling the heating means so that the detected temperature value becomes equal to a set value. Screen printing machine.