阅读说明：本技术 印刷丝网框架固定装置 (Printing screen frame fixing device ) 是由 崔顺本 于 2018-08-24 设计创作，主要内容包括：本发明的印刷丝网框架固定装置的结构是在活塞杆因空气压供应而后退时,拉伸构件的结合凸起与印刷丝网单元的支撑框架的拉伸力解除,可以更换印刷丝网单元,当弹性弹簧因空气压中断而膨胀,活塞杆前进时,借助于弹力而加压,使得拉伸构件的结合凸起与印刷丝网单元的支撑框架挂接而使印刷丝网拉伸后,可以根据需要,利用空气压而进行逆向加压,由于这种结构,因而可以在不发生因异物质及摩擦导致的变形破损而半永久性地使用的同时,可以根据长期使用时松驰的印刷丝网拉伸值变化来重新调整不足的拉伸力。(The printing screen frame fixing device of the present invention is configured such that when the piston rod is retracted by air pressure supply, the engaging projection of the tension member is released from the tension of the support frame of the printing screen unit, so that the printing screen unit can be replaced, and when the elastic spring is expanded by interruption of the air pressure and the piston rod is advanced, the elastic spring is pressed by the elastic force so that the engaging projection of the tension member is engaged with the support frame of the printing screen unit to tension the printing screen, and then the printing screen can be reversely pressed by the air pressure as necessary.)

1. A printing screen frame fixing apparatus configured to replace or stretch a printing screen unit (5) by means of a frame fixing apparatus (120), wherein the frame fixing apparatus (120) is made into a quadrangular frame shape using a plurality of attachment frames (130) provided with a stretching operation portion (150) and a plurality of corner pieces (140), characterized in that,

the stretching operation section (150) includes:

a cylinder tube body (151), wherein the cylinder tube body (151) is combined with the inner side surface of the hollow hole (132) of the additional frame (130) at a preset distance, and partition walls (151b) with preset intervals are arranged between the cylinder tube body and the additional frame along the length direction to form a plurality of circular through holes (151 a);

a plurality of piston rods (152), the plurality of piston rods (152) being constituted by a head portion (152a) and a rod portion (152b) so as to be closely inserted into the plurality of circular through holes (151a) and horizontally move, respectively;

a plurality of cylinder rod covers (153) in which through holes (153a) are formed so that the rod part (152b) closely penetrates and horizontally moves while being screwed to outer ends of the plurality of circular through holes (151a), respectively;

a plurality of elastic springs (154), wherein the plurality of elastic springs (154) are respectively inserted between the head (152a) and the cylinder rod cover (153) in the plurality of circular through holes (151a), and apply elastic force to the inner side of the circular through holes (151 a);

and a plurality of tension members (155), which are inserted into the hollow (132) in a lengthwise direction in a long manner while being coupled to the outer ends of the rods (152b), and in which coupling bosses (155a) formed at the lower side are projected through lower side operation guide holes (133) of the hollow (132) to be slid in a horizontal direction so as to be coupled to or separated from the support frame (5b) of the printing screen unit (5).

2. The printing screen frame attachment arrangement of claim 1,

an inclined surface (136) having a height gradually decreasing from the operation guide hole (133) to an outer end is formed at a bottom of the hollow (132),

inclined surfaces (155b) having a height gradually lower from the coupling protrusions (155a) to the outer ends are formed at the lower ends of the plurality of tensile members (155) so that the tensile members (155) are moved by the secondary pressurization and then are engaged with the inclined surfaces (136) on the side of the hollow (132) and are stopped.

3. The printing screen frame attachment arrangement of claim 1,

the cylinder tube body (151) includes:

a plurality of circular through holes (151a), the circular through holes (151a) being horizontally formed to a predetermined depth on the inner side surface of the cylinder tube body (151), and formed by interposing partition walls (151b) at predetermined intervals in the longitudinal direction;

air pressurization releasing holes (151c) respectively formed at inner ends of the partition walls (151b) to connect passages so that the heads (152a) of the plurality of piston rods (152) are simultaneously pushed toward a releasing direction and retreated by air supplied through the first air injection port (142) of the corner piece (140);

air pressurizing holes (151d), which are respectively formed in the middle of the partition walls (151b), connect passages so that the heads (152a) of the plurality of piston rods (152) are simultaneously pushed toward a pressurizing direction and advanced by air supplied through the second air injection ports (144) of the corner pieces (140).

4. The printing screen frame attachment arrangement of claim 3,

the air pressurization releasing hole (151c) and the air pressurization hole (151d) are formed in the partition wall (151b) at the same height and width with a predetermined distance.

5. The printing screen frame attachment arrangement of claim 3,

the air pressurization releasing hole (151c) is configured to supply air to a space inside a circular through hole (151a) defined by a head portion (152a) of the piston rod (152) as a boundary, and not to be mixed with air passing through the air pressurization hole (151 d).

6. The printing screen frame attachment arrangement of claim 3,

the air pressurization hole (151d) is configured to supply air to a space outside a circular through hole (151a) defined by the head (152a) of the piston rod (152) as a boundary, and is not mixed with air passing through the air pressurization release hole (151 c).

7. The printing screen frame attachment arrangement of claim 1,

a stop protrusion (152c) is formed on the outer peripheral surface of the rod part (152b) at a predetermined distance from the end thereof, and the stop protrusion (152c) is engaged with a cylinder rod cover (153) when the piston rod (152) moves in the release direction, and is controlled so that the elastic spring (154) cannot be compressed by an appropriate pressure or more.

8. The printing screen frame attachment arrangement of claim 1,

hanging grooves (134) (135) are formed in the top inner side corner and the bottom outer side corner of the hollow (132), respectively, so that the stretching operation part (150) can be hung and fixed when being inserted through the hollow (134) along the length direction;

hanging protrusions (151e) and (151f) are respectively protruded from the upper end angle of the inner side surface and the lower end of the outer side surface of the cylinder tube body (151) so as to be hung corresponding to the hanging grooves (134) and (135) on the side of the hollow hole (132) to fix the position of the cylinder tube body (151).

Technical Field

The present invention relates to a printing screen frame fixing device, and more particularly, to a printing screen frame fixing device which can be manufactured to stretch a printing screen with an appropriate pressure by means of a cylinder type stretching operation portion using elastic force and air pressure.

Background

In general, the printing screen unit constitutes a rectangular printing screen forming a pattern of printing holes and a support frame including first and second pairs of interfacing portions and first to fourth corner pieces, the first and second pairs of interfacing portions being fittingly attached to respective pairs of edge portions of the printing screen in opposition to each other with a connecting member as a medium, the first to fourth corner pieces connecting the respective interfacing portions.

Among them, the printing screen is a metal thin film widely used in semiconductor manufacturing technology, and particularly in surface mounting technology, used when applying a solder paste for mounting a chip or the like on a printed circuit board or the like, or during exposure work, or the like.

The printing screen is also called a metal mask or a stencil mask, is provided with fine printing holes in a predetermined pattern, is mounted on equipment such as a screen printer, an exposure device, and a cleaning device, and can be replaced at any time when a different pattern is required.

The printing screen is used in a state of being attached to the support frame, but if there is a slack portion, the position of the printing pattern is misaligned or the printing pattern is distorted when the printing screen is scraped by the squeegee. In order to prevent this, when screen printing is performed, it is necessary to apply a tensile force to the printing screen, to provide a predetermined tensile force to the printing screen at all times, and to have a detachable function so as to be replaced at any time when a printing screen of another pattern is required.

That is, since the printing screen is used by being attached to equipment such as a screen printer for a printed circuit board using a support frame as a medium and needs to be periodically replaced and cleaned, a fixing device including a lifting operation portion that needs to be attached and detached and a stretching operation portion that needs a stretching force functions as an important factor.

In view of the above, the printing screen frame fixing apparatus of the prior art issued patent No. 10-1685899 (2016, 12, 7) is configured such that the printing screen unit 5 is replaced or stretched by the frame fixing apparatus 20 which is made into a rectangular frame shape by the plurality of attached frames 30 and the plurality of corner members 40, as shown in fig. 1 and 2.

That is, the plurality of attachment frames 30 are made of aluminum material formed in a predetermined length by extrusion molding, and have air pressure supply holes 32 formed to extend through in the longitudinal direction at the upper height side of the cross section, and cavities 34 formed to extend through in the longitudinal direction at the middle height of the cross section.

In this case, the hollow 34 is formed in a rectangular shape having a lateral width larger than a vertical height, an operation guide hole 36 is formed at the center of the bottom surface so as to be elongated in the longitudinal direction of the attachment frame 30, a partition wall 38 is formed at the center of the top surface so as to be elongated in the longitudinal direction of the attachment frame 30, the lower end of the partition wall 38 is separated from the bottom of the hollow 34 without touching the bottom of the hollow 34, is positioned at the center of the operation guide hole 36, and is divided into an inner hollow 34a and an outer hollow 34b, and a tensile operation portion 50 is attached so as to extend across the inner hollow 34a and the outer hollow 34 b.

The stretching operation part 50 includes: a plurality of tension members 52, which tension members 52 interpose the partition wall 38 therebetween, and whose side projections 52a, 52b are respectively located in the inner cavity 34a and the outer cavity 34b, and whose lower engaging projections 52c project through the operating guide holes 36 to slide in the horizontal direction so as to be engaged with or disengaged from the support frame 5b of the printing screen unit 5; a cylinder 54 which is located between the side surface projection 52a of the tensile member 52 and the partition wall 38, and which slides the tensile member 52 into the inner cavity 34a to release the tensile force when the cylinder 54 is expanded by the air pressure; and an elastic member 56, wherein the elastic member 56 is positioned between the side surface projection 52b of the tensile member 52 and the partition wall 38, and when the air pressure is released, the tensile member 52 slides to the outer cavity 34b by an elastic force to apply a tensile force.

In the conventional printing screen frame fixing apparatus configured as described above, if air is injected through the one-side inlet port 48 of the frame fixing apparatus 20 which is formed in a quadrangular frame shape by the plurality of attached frames 30 and the corner fittings 40 without using a separate tool or adding accessories, the elevating and lowering operation unit 60 and the stretching operation unit 50 are sequentially operated at intervals of several seconds by adjusting the air pressure supply speed through the orifice, and the printing screen unit 5 is elevated and lowered so as to be supported by the edge thereof, and the printing screen unit 5 is engaged with the edge thereof and a stretching force is applied thereto so as to tension the printing screen 5a in four directions.

That is, if high-pressure air is injected into the main body 42 of the corner fitting 40 from an external separate air supply device, the cylinder 54 is inflated by the air pressure and operated in a direction to release the stretching by the stretching operation portion 50 as shown in fig. 2(b), so that the printing screen unit 5 can be replaced.

Further, if the supply of the air pressure to the frame fixing device 20 is interrupted, as shown in fig. 2a, the cylinder 54 of the stretching operation portion 50 is in a state of releasing the air pressure, and the elastic member 56 that has been compressed expands and compresses the cylinder 54, and at the same time, the stretching member 52 slides in the inner hollow 34a of the attachment frame 30 to horizontally move to the outer hollow 34b, and the coupling projections 52c of the stretching member 52 are engaged with the engagement ribs of the support frame 5b of the printing screen unit 5 and coupled with each other, and therefore, the printing screen 5a is stretched by receiving a tensile force in all directions.

However, the conventional printing screen frame fixing device thus constructed is constructed in such a manner that, when the cylinder 54 is expanded by the supply of air pressure, the hooking force of the engaging projection 52c of the tension member 52 to the support frame 5b of the printing screen unit 5 is released, when the cylinder 54 is contracted by the expansion of the elastic member 56 due to the interruption of the air pressure, the engaging projection 52c of the tension member 52 is hooked on the support frame 5b of the printing screen unit 5 to tension the printing screen 5a, due to this structure, when the cylinder 54 is used for a long period of time, it is oxidized or broken due to foreign substances and friction, therefore, the replacement of the cylinder 54 at any time is unavoidable, and in addition, not only the expansion force of the cylinder 54 and the elastic member 56 is limited, furthermore, since the moving distance within the tension member 52 is also limited, there is a problem that the tension cannot be readjusted to an appropriate tension in accordance with the change in the tension of the printing screen 5a that is slack during long-term use.

Disclosure of Invention

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a printing screen frame fixing apparatus which can be used semi-permanently without deformation and damage due to foreign matter and friction, and which can readjust a stretching force in accordance with a change in a stretching value of a printing screen which is loosened during long-term use.

A printing screen frame fixing apparatus according to an embodiment of the present invention for solving the above-described problems is configured such that a printing screen unit is replaced or stretched by a frame fixing apparatus which is made into a quadrangular frame shape by using a plurality of attachment frames and a plurality of corner fittings each having a stretching operation portion, wherein the stretching operation portion includes: the cylinder barrel body is combined with the inner side surface of the cavity 132 of the additional frame in a mode of setting a set distance, and partition walls at set intervals are arranged between the cylinder barrel body and the inner side surface along the length direction to form a plurality of circular through holes; a plurality of piston rods composed of a head portion and a rod portion so as to be closely inserted into the plurality of circular through holes, respectively, and horizontally moved; a plurality of cylinder rod covers having through holes formed therein so that the rod portions closely penetrate and horizontally move while being screwed to outer ends of the plurality of circular through holes, respectively; a plurality of elastic springs which are respectively inserted between the head and the cylinder rod cover inside the plurality of circular through holes and apply elastic force to the inner sides of the circular through holes; and a plurality of tension members which are inserted into the hollow in a longitudinal direction in a long manner while being coupled to outer ends of the rod portions, and coupling bosses formed below are projected through lower side operation guide holes of the hollow, and are slid in a horizontal direction so as to be coupled to or separated from the support frame of the printing screen unit.

As another embodiment, a slope having a height gradually decreasing from the operation guide hole to the outer end is formed at the bottom of the hollow, and a slope having a height gradually decreasing from the coupling protrusion to the outer end is formed at the lower end of the plurality of tensile members, so that the tensile members are moved by the secondary pressurization and then are engaged with the hollow-side slope and stopped.

As another embodiment, the cylinder tube body of the present invention is characterized by comprising: a plurality of circular through holes horizontally formed to a predetermined depth on the inner side surface of the cylinder tube body, and formed by interposing partition walls at predetermined intervals therebetween in the length direction; air pressurization releasing holes formed at inner side ends of the partition walls, respectively, connecting passages so that the heads of the plurality of piston rods are simultaneously pushed toward a releasing direction and retreated by air supplied through the first air injection port of the corner piece; air pressurizing holes, which are respectively formed in the middle of the partition walls, connect the passages so that the air supplied through the second air injection port of the corner piece simultaneously pushes the heads of the plurality of piston rods toward the pressurizing direction and advances.

As another embodiment, the air pressurization releasing hole and the air pressurization hole of the present invention are formed at the same height and width in the partition wall with a predetermined distance.

In another embodiment, the air pressurization releasing hole of the present invention is configured to supply air to a space inside the circular through hole defined by the head portion of the piston rod, and not to mix with air passing through the air pressurization hole.

In another embodiment, the air pressurizing hole of the present invention is configured to supply air to a space outside the circular through hole defined by the head portion of the piston rod, and not to mix with air passing through the air pressurizing release hole.

As another embodiment, a stop protrusion is formed on an outer peripheral surface of the rod portion of the present invention at a predetermined distance from a distal end thereof, and the stop protrusion is engaged with the rod cover when the piston rod moves in the release direction, so that the elastic spring is controlled not to be compressed by an appropriate pressure or more.

As another embodiment, the present invention is characterized in that hanging grooves are formed at the top inner side corner and the bottom outer side corner of the hollow space, respectively, so that the stretching operation portion is hung and fixed when inserted through the hollow space in a long length direction; hanging protrusions are respectively protruded at the upper end angle of the inner side surface and the lower end of the outer side surface of the cylinder barrel body so as to be correspondingly hung with the hanging grooves on the side of the hollow hole 132 and fix the position of the cylinder barrel body.

The printing screen frame fixing device of the present invention has a structure in which when the piston rod is retracted by air pressure supply, the coupling protrusion of the tension member is released from the tension of the support frame of the printing screen unit, so that the printing screen unit can be replaced, and when the elastic spring is expanded by interruption of the air pressure and the piston rod is advanced, the elastic spring applies pressure to the coupling protrusion of the tension member and the support frame of the printing screen unit, so that the printing screen unit is stretched, and then the printing screen unit can be reversely pressed by the air pressure as necessary.

Drawings

Figure 1 is a combined perspective view illustrating a state in which a printing screen is attached to a conventional printing screen frame fixing device,

FIG. 2 is a longitudinal sectional view illustrating a drawing operation part taken along line A-A of FIG. 1,

figure 3 is a bottom view illustrating the condition of a printing screen being loaded onto the printing screen frame securement device of the present invention,

FIG. 4a and FIG. 4B are sectional views enlarged from the portion B of FIG. 3,

figures 5a and 5b are bottom and top perspective views illustrating the state in which the cylinder bore bodies of the present invention are connected by means of corner pieces,

FIG. 6 is an exploded perspective view illustrating a piston rod, an elastic spring, and a cylinder rod cover of the present invention,

FIG. 7 is a longitudinal sectional view illustrating a drawing operation part at the line C-C of FIG. 3,

fig. 8 is a use state diagram for explaining a process of adjusting the air injection amount by a moderate tensile force indicated by the tensile gauge placed at the center of the printing screen of the present invention.

Reference numerals

5: printing screen unit 5 a: printing screen

5 b: the support frame 120: frame fixing device

130: the additional installation of the frame 131: air pressure supply hole

132: cavity 133: operation guide hole

134,135: hanging groove 136: inclined plane

140: corner fitting 142: first air injection port

144: second air injection port 150: stretching operation part

151: cylinder tube body 151 a: round through hole

151 b: partition wall 151 c: air pressurization relieving hole

151 d: air pressurizing holes 151e,151 f: hanging projection

152: piston rod 152 a: head part

152 b: shaft portion 152 c: stop projection

153: cylinder rod cover 153 a: through hole

154: the elastic spring 155: tension member

155 a: the engaging projection 155 b: inclined plane

156,157: o-ring 158: connecting screw

159: o-shaped ring

Detailed Description

An embodiment of the present invention will be described in detail with reference to fig. 3 to 8.

The same names and the same symbols are given to the same components of the present invention as those of the conventional components, and redundant description is omitted.

The printing screen frame attachment of the present invention is configured to replace or stretch the printing screen unit 5 by means of a frame attachment 120, as shown in figure 3, wherein the frame attachment 120 is made in the shape of a four-sided frame using a plurality of attachment frames 130 and a plurality of corner pieces 140.

That is, the plurality of attachment frames 130 are made of aluminum material formed in a predetermined length by extrusion molding, and have inner corners at the inner top thereof, and when the corner fitting 140 is connected to the attachment frame 130, air pressure supply holes 131 are formed to extend through in the longitudinal direction, and cavities 132 are formed to extend through in the longitudinal direction at the remaining end surfaces except for the portion where the air pressure supply holes 131 are formed.

In this case, the hollow 132 is formed in a rectangular shape having a lateral width larger than a vertical height, and has an operation guide hole 133 formed at a center of a bottom portion thereof to extend in a longitudinal direction of the attachment frame 130, and hooking grooves 134 and 135 formed at inner corners of a top portion and outer corners of a bottom portion thereof, respectively, for hooking and fixing the tensile operation portion 150 to a fixed position when the tensile operation portion is inserted into the hollow 134 in the longitudinal direction, and an inclined surface 136 formed at the bottom portion of the hollow 132 extending outward with the operation guide hole 133 interposed therebetween to have a height gradually lower from the operation guide hole 133 toward an outer end.

The stretching operation part 150 includes: a cylinder tube body 151, the cylinder tube body 151 being inserted lengthwise along the longitudinal direction in such a manner as to be closely attached to the outer side surface, the top portion and the bottom portion of the hollow 132, and being fixed by a plurality of ribs 134, and having a plurality of circular through holes 151a formed so as to be spaced apart from the inner side surface of the hollow 132 by a predetermined distance; a plurality of piston rods 152, the plurality of piston rods 152 being constituted by a head portion 152a and a rod portion 152b so as to be closely inserted into the plurality of circular through holes 151a, respectively, and horizontally moved; a plurality of cylinder rod covers 153, each of the cylinder rod covers 153 having a through hole 153a so that the rod portion 152b can be tightly inserted through and horizontally moved while being screwed to the outer ends of the circular through holes 151a via an O-ring 159; a plurality of elastic springs 154, each of the plurality of elastic springs 154 being inserted between the head 152a and the cylinder rod cover 153 inside the plurality of circular through holes 151a, and applying an elastic force to the inside of the circular through hole 151 a; and a plurality of tension members 155 which are inserted into the hollow 132 in a longitudinal direction, coupled to outer ends of the rod portions 152b of the plurality of piston rods 152 via a plurality of coupling screws 158, and have lower coupling bosses 155a which protrude through the operation guide holes 133 and slide in a horizontal direction so as to be coupled to and separated from the support frame 5b of the printing screen unit 5.

In this case, the cylinder tube body 151 is made of an aluminum material formed in a predetermined length by extrusion molding so as to form a rectangular shape having a lateral width greater than a vertical height, and includes: a plurality of circular through holes 151a horizontally formed to a predetermined depth on an inner side surface of the cylinder tube body 151, and formed by interposing partition walls 151b at predetermined intervals in a longitudinal direction therebetween; air pressurization releasing holes 151c formed at the inner ends of the partition walls 151b with the same height and width, respectively, connecting channels such that the heads 152a of the plurality of piston rods 152 are simultaneously pushed toward a releasing direction and retreated by air supplied through the first air injection port 142 of the corner piece 140; air pressurizing holes 151d, respectively formed at the same height and width in the middle of the partition wall 151b, connecting passages so that the heads 152a of the plurality of piston rods 152 are simultaneously pushed toward the pressurizing direction and advanced by the air supplied through the second air injection port 144 of the corner piece 140; and hooking protrusions 151e and 151f, the hooking protrusions 151e and 151f protruding from the upper end corner of the inner side surface and the lower end of the outer side surface of the cylinder tube body 151 respectively, hooking grooves 134 and 135 formed in the inner side corner of the top and the outer side corner of the bottom of the cavity 132, and fixing the cylinder tube body 151.

An O-ring 156 for sealing a gap between the inner peripheral surface of the circular through hole 151a on the cylinder tube body 151 side and the head 152a is coupled to the outer peripheral surface of the head 152a on the piston rod 152 side, an O-ring 157 for sealing a gap between the inner peripheral surface of the cylinder rod cover 153 and the rod 152b is coupled to the outer peripheral surface spaced apart from the end of the rod 152b by a predetermined distance, a stop protrusion 152c is formed on the outer peripheral surface spaced apart from the end of the rod 152b by a predetermined distance, and the stop protrusion 152c is controlled so as to be caught to the cylinder rod cover 153 when the piston rod 152 moves in the release direction, and the elastic spring 154 is not compressed by an appropriate pressure or more.

The plurality of tensile members 155 are made of aluminum formed in a predetermined length by extrusion so as to form an l-shape having a coupling protrusion 155a protruding at the center of the lower portion thereof, and have inclined surfaces 155b formed at the lower ends thereof so that the height thereof becomes lower from the coupling protrusion 155a to the outer ends thereof, so that the tensile members 155 move by the secondary pressing and then stop while being matched with the inclined surfaces 136 formed at the bottom of the hollow 132.

The operation and effect of the printing screen frame fixing device of the present invention thus constituted will be described below.

The printing screen frame fixing apparatus of the present invention relates to a frame fixing apparatus 120 which is manufactured in a four-sided frame shape by means of a plurality of attached frames 130 and a corner fitting 140 having a stretching operation part 150 therein, and if air is injected in a direction indicated by an arrow D in fig. 4a through a first air injection port 142 formed at one side of the corner fitting 140 and then discharged after several seconds, the supply speed of air pressure is adjusted by means of an orifice, so that a lifting operation part (not shown) at the side of the corner fitting 140 operates first as in the conventional configuration, lifts up and lowers to support the edge of a support frame 5b of a printing screen unit 5, and at the same time, the stretching operation part 150 is made to coincide with the support frame 5b of the printing screen unit 5, and then, at intervals of several seconds, the stretching operation part 150 constructed in the present invention retreats by means of the supplied air pressure, and when the supply of air is released, advances by means of the elastic force and pulls the support frame 5b of the printing screen unit 5, which is fitted to the edge of the printing screen unit 5, in four directions, thereby applying a tensile force to hold the printing screen 5a in a tensile taut state.

That is, if air is supplied through the air pressure release holes 151c formed in the respective circular through holes 151a of the cylinder tube main body 151 on the side of the stretching operation portion 150, the air pressure causes the piston rod 152 at the position shown in fig. 7d to retreat, and the stretching member 155 joined to the tip of the rod portion 152b of the piston rod 152 via the coupling screw 158 to retreat simultaneously, and the coupling boss 155a protruded on the lower surface of the stretching member 155 is engaged with the support frame 5b of the printing screen unit 5 in the standby state by the ascending operation of the elevating operation portion (not shown in the drawings) on the side of the corner fitting 140 which operates first several seconds as shown in fig. 7 c.

In this state, if the air pressure supplied in the direction indicated by the arrow D in fig. 4a is interrupted, as shown in fig. 7b, the air pressure in the circular through hole 151a of the cylinder tube body 151 is released, and therefore, the elastic spring 154, which has been once compressed, expands and advances the piston rod 152, and at the same time, the tension member 155 coupled to the tip end of the rod portion 152b simultaneously advances outward, so that the support frame 5b of the printing screen unit 5, which is fitted to the coupling projection 155a of the tension member 155, is pulled in four directions, and a tensile force is applied to keep the printing screen 5a in a stretched and tensed state.

At this time, the elastic spring 154 is operated only with a predetermined elastic force, and therefore, the tension force cannot be further increased in accordance with the change in the tension value of the printing screen 5a that is loosened in long-term use, but if air pressure is supplied to a point intermediate the head portion 152a of the piston rod 152 and the through hole 151a of the cylinder tube main body 151 on the side between the cylinder rod cover 153, the piston rod 152 can be further advanced to move the tension member 155.

That is, in the case of readjusting to increase the tension according to the change in the tension value of the printing screen 5a which is loosened in long-term use, first, if the data value of the tension meter F placed at the center of the printing screen 5a as shown in fig. 8 is confirmed and air is injected through the second air injection port 144 of the angle 140 as shown in the arrow E direction of fig. 4b, the air pressure is supplied to the middle point of the side circular through hole 151a between the head 152a of the piston rod 152 and the rod cover 153 through the air pressurizing hole 151d formed at the center of the partition wall 151b connecting the plurality of circular through holes 151a of the cylinder tube body 151, so that the tension member 155 is advanced while the piston rod 152 is advanced further as shown in fig. 7a, and thus the support frame 5b of the printing screen unit 5 which is fitted with the coupling boss 155a of the tension member 155 is advanced further by the reverse pressurization by the air pressure, and pulls the printing screen 5a, which is supported by the support frame 5b, in four directions.

At this time, when the piston rod 152 is further advanced by the reverse pressurization by the air pressure as shown in fig. 7a, the force to advance the vertical end of the tension member 155 coupled to the tip end of the rod portion 152b via the coupling screw 158 collides with the force to advance the horizontal end side coupling projection 155a of the tension member 155 to the support frame 5b of the printing screen unit 5 without being pulled upward, and is shifted by the predetermined angle α, so that even if the air pressure supplied through the second air inlet 144 is released, the tension member 155 thus shifted is supported by the strong frictional force of the inclined surface 136 formed at the bottom of the cavity 132 and the inclined surface 155b formed at the lower tip end of the tension member 155, and thus the reverse pressurization force applied to the printing screen 5a is not released.

Of course, in order to release the stretching of the piston rod 152 by the counter pressure due to the air pressure as shown in fig. 7c, the stretching member 155 coupled to the end of the rod portion 152b of the piston rod 152 is retracted by the air pressure supplied to the air pressure release hole 151c inside the circular through hole 151a through the first air inlet 142, and the frictional force generated by the angle of the offset and the inclined surfaces 136 and 155b is released, so that the printing screen unit 5 can be returned to the original state in which it is possible to replace the printing screen unit.

The printing screen frame fixing apparatus of the present invention is, therefore, constructed such that, when the piston rod 152 is retracted by the supply of air pressure, the tensile force of the engaging projection 155a of the tensile member 155 and the support frame 5b of the printing screen unit 5 is released, the printing screen unit 5 can be replaced by, when the resilient spring 154 expands due to a break in air pressure, the piston rod 152 advances, being pressurized by means of the resilient force, after the printing screen 5a is stretched by hooking the engaging projections 155a of the stretching member 155 to the support frames 5b of the printing screen unit 5, the printing screen unit can be reversely pressurized by air pressure as required, with this structure, the utility model has the advantages that the utility model can be used semi-permanently without deformation and damage caused by foreign matters and friction, the insufficient tension can be readjusted in dependence on the change in tension of the printing screen 5a which is loose during long-term use.

In particular, the attachment frame 130 and the tension operation unit 150 constituting the frame fixing device 120 can adjust and readjust the tension to a desired tension according to the tendency of the printing screen 5a to be loosened during long-term use or to become thinner, as the thickness of the printing screen 5a becomes thinner, thereby providing an advantage that not only can a predetermined quality be maintained, but also the life of the printing screen 5a can be extended.

On the other hand, the present invention is not limited to the above-described embodiments, and modifications and variations can be made within a scope not departing from the gist of the present invention, and the technical idea of applying such modifications and variations should be regarded as belonging to the claims below.