WO2004048283A1

WO2004048283A1 - Chuck for clamping glass tube

Info

Publication number: WO2004048283A1
Application number: PCT/KR2003/002566
Authority: WO
Inventors: Ick-Soo Choi
Original assignee: Ick-Soo Choi
Priority date: 2002-11-26
Filing date: 2003-11-26
Publication date: 2004-06-10
Also published as: KR20030011030A; AU2003284766A1; KR100477398B1

Abstract

The present invention relates to a chuck for clamping a glass tube, and more particularly, to a chuck for clamping a glass tube, which is used in a blowing machine for manufacturing a glass bottle, an ampule, an electric bulb or the like by blowing air in a glass tube having a predetermined length and both ends formed into a flare portion and a dome portion, respectively. The chuck for clamping a glass tube according to the present invention comprises a housing; a clamping means that is installed on the housing to be rotatable about a predetermined axis, is formed with a through-hole with a predetermined diameter along the predetermined axis, and has a gasping portion for clamping an upper end of the glass tube below the through-hole such that a central axis of the glass tube is substantially aligned with the predetermined axis; a power transmitting means installed in the housing to transmit power for rotating the clamping means; and a clutch for receiving the power from the power transmitting means and transmitting the received power to the clamping means, whereby when external force exceeding a predetermined value is applied to the clamping means, the gasping portion of the clamping means is outstretched to clamp the upper end of the glass tube or release a clamped glass tube and the clutch cuts off the power transmitted to the clamping means.

Description

CHUCK FOR CLAMPING GLASS TUBE

Technical field

The present invention relates to a chuck for clamping a glass tube, and more particularly, to a chuck for clamping a glass tube, which is used in a blowing machine for manufacturing a glass bottle, an ampule, an electric bulb or the like by blowing air in a glass tube having a predetermined length and both ends formed into a flare portion and a dome portion, respectively.

Background Art

A glass bottle, an ampule, an electric bulb or the like is manufactured by a blowing process performed in a state where a glass tube has been heated. A conventional blowing machine for manufacturing a vessel from such a glass tube employs a method comprising the steps of directly heating a long glass tube, locating a heated portion of the glass tube in a predetermined mold and then blowing air into the glass tube. A chuck for clamping the glass tube is used in the conventional blowing machine in order to uniformly heat a portion of the glass tube to be processed while rotating the glass tube at a constant speed, and to ensure a uniform thickness of the product. Chucks for clamping long glass tubes are disclosed in U.S. Patent Nos. 4,092,142, 5,178,401 and 4,832,726, Japanese Patent Laid- Open Publication No. S60-42241, Korean Utility Model Registration No. 1985-0002912, and the like.

However, since a long glass tube is supplied continuously from above the chuck for clamping the glass tube and then subjected to the blowing process in the conventional blowing machine, a substantial amount of glass tube should be cut away to form dome portions of separate glass tubes. Therefore, there is a problem in that materials are wasted.

In order to prevent the waste of the materials, there is a need for the development of a blowing machine, wherein a glass-tube preform of which one end is formed into an open flare portion in the form of a morning glory and the other end is formed into a dome portion is directly supplied and then subjected to a blowing process, without continuously supplying a long glass tube.

Disclosure of Invention

An object of the present invention is to provide a chuck for clamping a glass tube which can be used in such a blowing machine described above, specifically, a chuck for clamping a glass tube which is suitable for clamping a glass tube with a predetermined length, rotating the clamped glass tube and injecting air into the glass tube.

A chuck for clamping a glass tube according to the present invention for achieving this object comprises a housing; a clamping means that is installed on the housing to be rotatable about a predetermined axis, is formed with a through-hole with a predetermined diameter along the predetermined axis, and has a grasping portion for clamping an upper end of the glass tube below the through-hole such that a central axis of the glass tube is substantially aligned with the predetermined axis; a power transmitting means installed in the housing to transmit power for rotating the clamping means; and a clutch for receiving the power from the power transmitting means and transmitting the received power to the clamping means, whereby when external force exceeding a predetermined value is applied to the clamping means, the grasping portion of the clamping means is outstretched to clamp the upper end of the glass tube or release a clamped glass tube and the clutch cuts off the power transmitted to the clamping means. With such a constitution, the chuck for clamping the glass tube according to the present invention is installed on a predetermined rotary table by fixing the housing to a periphery of the rotary table. The clamping means clamps the upper end of the glass tube below the through-hole using the grasping portion. The glass tube clamped as described above is transferred to respective processing stages by means of the rotation of the rotary table. In the state where the chuck for clamping the glass tube according to the present invention is fixed to the rotary table as described above, the power transmitting means receives power for rotating the clamping means from an external power source and transmits the power to the clamping means. Accordingly, the clamped glass tube is rotated. Further, the through-hole provides a passage for allowing a predetermined air injection nozzle to access an upper opening of the glass tube to inject air into the clamped glass tube. Meanwhile, if external force exceeding a predetermined value is applied so that the clamping means can clamp or release the glass tube, the clutch cuts off the power transmitted to the clamping means.

Preferably, in the chuck for clamping the glass tube according to the present invention, the clamping means further comprises a rotational member that rotates by receiving the power from the clutch and is formed with the through-hole, and a grasping portion-driving means installed on the rotational member to pucker or outstretch the grasping portion. Clamping parts of the grasping portion for clamping the glass tube are installed below the through-hole of the rotational member, and the external force exceeding the predetermined value is applied to the grasping portion-driving means. Preferably, in the chuck for clamping the glass tube according to the present invention, the clutch is installed between the power transmitting means and the rotational member.

Preferably, in the chuck for clamping the glass tube according to the present invention, the rotational member comprises a guide portion formed by extending an outer periphery of the through-hole by a predetermined length along the axis; the grasping portion comprises a disk-shaped jaw base that has a through-hole formed therein and is installed at a lower end of the guide portion of the rotational member to be concentric with the through-hole of the rotational member, pivoting shafts disposed at a predetermined interval along the same circumference at an outer periphery of the jaw base and arranged perpendicularly to a plane including the axis, and a plurality of jaws pivotably mounted at the respective pivoting shafts such that at least a portion of each of the jaws protrudes above the jaw base; the grasping portion-driving means comprises a pressing plate that is installed to be movable vertically along the guide portion and has a pressing surface provided at a bottom surface thereof to come into contact with the protruding portions of the jaws so that the jaws can pivot, a spring installed at the guide portion such that a lower side of the spring is in contact with a top surface of the pressing plate, and a stopper that is in contact with an upper side of the spring and fixedly installed at the guide portion; and the external force exceeding the predetermined value is applied upward to the bottom surface of the pressing plate. With such a constitution, when the pressing plate moves downward by means of the elastic force of the spring, the plurality of jaws pivot and are puckered toward the axis to clamp the glass tube. When the pressing plate moves upward by means of the external force exceeding the predetermined value, the plurality of jaws pivot and are outstretched away from the axis to release the clamped state of the glass tube.

Preferably, in the chuck for clamping the glass tube according to the present invention, the center of gravity of each of the jaws is located inside the concentric circumference on which the pivoting shafts are installed.

With such a constitution, when the pressing plate moves upward, contact between the pressing surface and the protruding portions of the jaws is released, and at the same time, the plurality of jaws pivot and are outstretched away from the axis by means of their dead weight.

Preferably, in the chuck for clamping the glass tube according to the present invention, the number of the jaws is three, and the protruding portion of each of the jaws is provided with a roller that comes into contact with and rolls on the pressing surface.

With such a constitution, the rollers reduce friction force between the protruding portions of the plurality of jaws and the pressing surface, thereby facilitating the pivoting movement of the jaws.

Preferably, in the chuck for clamping the glass tube according to the present invention, the pressing surface of the pressing plate has a radius which gradually decreases toward the lower end of the guide portion, and a normal at a point where the roller comes into contact with the pressing surface passes outside the concentric circumference on which the pivoting shafts are installed. With such a constitution, when the pressing plate moves downward, the pressing surface applies force to the plurality of jaws in a direction of the normal, so that the plurality of jaws can pivot and be puckered toward the axis.

Preferably, in the chuck for clamping the glass tube according to the present invention, the rotational member comprises a guide portion formed by extending an outer periphery of the through-hole by a predetermined length along the axis; the grasping portion comprises a disk-shaped jaw base that has a through-hole formed therein and is installed at a lower end of the guide portion of the rotational member to be concentric with the through-hole of the rotational member, pivoting shafts disposed at a predetermined interval along the same circumference at an outer periphery of the jaw base and installed parallel with the axis, and a plurality of jaws having one ends fixed to lower ends of the respective pivoting shafts so that the jaws can pivot integrally with the pivoting shafts; the grasping portion-driving means comprises a plurality of driving link rods in which one ends thereof are fixed to upper ends of the respective pivoting shafts to pivot integrally with the respective pivoting shafts and the end of at least one of the driving link rods is provided with a projection extending in a direction opposite to the other end of the relevant driving link rod, connecting link rods each of which has both ends connected to the other ends of two driving link rods to pivot on axes parallel with the pivoting shafts, and a spring of which one side is connected to the projection of the relevant driving link rod and the other side is connected to an edge of the jaw base; and the external force exceeding the predetermined value is applied horizontally to at least one of connection portions of the driving link rods and the connecting link rods. With such a constitution, when the driving link rods connected to the connecting link rods pivot by means of the elastic force of the spring, the plurality of jaws clamp the glass tube in such a manner that the ends of the jaws are puckered toward the axis. When the driving link rods pivot by receiving the external force exceeding the predetermined value applied thereto, the clamped state is released due to the pivoting of the plurality of jaws in such a manner that the ends of the jaws are outstretched away from the axis.

Preferably, in the chuck for clamping the glass tube according to the present invention, the number of the jaws is two, and a grasping recess is formed in at least one of ends of the jaws by which the tube glass is clamped. With the grasping groove, the end of the jaw more securely comes into contact with the outer peripheral surface of the glass tube to clamp the glass tube.

Preferably, in the chuck for clamping the glass tube according to the present invention, the power transmitting means is a gear fitted around the guide portion, and the clutch is installed between the gear and the guide portion. With such a constitution, the gear transmits power from a given driving gear to the clamping means through the clutch.

Preferably, in the chuck for clamping the glass tube according to the present invention, the housing is provided with a cooling water flow passage in which cooling water flows. With such a constitution, the chuck for clamping the glass tube is cooled by the cooling water.

Preferably, in the chuck for clamping the glass tube according to the present invention, the clutch is a friction clutch including a friction pad that is installed in the gear to be in contact with an outer peripheral surface of the guide portion and rotates integrally with the gear. With such a constitution, when the external force exceeding the predetermined value is applied to the clamping means, a slip occurs at a contact portion of the friction pad and the outer peripheral surface of the guide portion. Therefore, even though the gear rotates, the clamping means does not rotate.

Preferably, in the chuck for clamping the glass tube according to the present invention, the gear is formed with at least three clutch mounting holes that penetrate through radially inner and outer walls of the gear and are disposed circumferentially at a predetermined interval. The friction clutch comprises an adjuster screw provided on a radially outer side in each of the clutch mounting holes to move radially inward and outward within the clutch mounting hole, a friction pad pressing spring inserted into each of the clutch mounting holes such that a radially outer end of the friction pad pressing spring is supported by a radially inner end of the adjuster screw, and a friction pad mounted on a radially inner side in each of the clutch mounting holes such that a radially outer end of the friction pad is supported by a radially inner end of the friction pad pressing spring and a radially inner end of the friction pad comes into contact with the outer peripheral surface of the guide portion. With such a constitution, the friction pad pressing spring applies elastic force to the friction pad so that the friction pad can come into close contact with the outer peripheral surface of the guide portion, and the rotational force is transmitted from the gear to the guide portion due to friction force at a contact surface of the friction pad and the guide portion. When the external force exceeding the predetermined value is applied to the clamping means, a slip occurs as the contact surface.

Brief Description of Drawings

Fig. 1 is an exploded perspective view of a chuck for clamping a glass tube according to an embodiment of the present invention. Fig. 2 is a side view schematically showing a state where a clamping means of the chuck for clamping the glass tube according the embodiment of the present invention shown in Fig. 1 is operated.

Fig. 3 is a schematic view showing a center of gravity of a jaw and a contact relationship between a pressing surface of a pressing plate and a roller in the chuck for clamping the glass tube according the embodiment of the present shown in Fig. 1.

Fig. 4 is a sectional view showing a state where a tube glass clamped by the chuck for clamping the glass tube according to the embodiment of the present invention shown in Fig. 1 is subjected to a blowing process by means of a mold and an air-injection device.

Fig. 5 is an exploded perspective view of a chuck for clamping a glass tube according to another embodiment of the present invention.

Figs. 6 (A) and (B) are a plan view and a bottom view schematically showing the operation of a clamping means of the chuck for clamping the glass tube according to the other embodiment of the present invention shown in Fig. 5, respectively.

40: Glass tube 100, 200: Chuck for clamping glass tube

110, 210: Housing 120, 220: Clamping means

122, 222: Guide portion 130, 230: Grasping portion

131, 231: Jaw base 132b, 234a, 235a: Pivoting shaft 137: Roller 134, 234, 235: Jaw

140, 240: Grasping portion-driving means

141: Stopper 143: Spring

145: Pressing plate 146: Pressing surface

150, 250: Gear 160: Clutch 161: Adjuster screw 162 : Spring

163: Friction pad 241 , 243 : Driving link rod

242: Connecting link rod 247: Spring

170: Fixing ring Best Mode for Carrying out the Invention

Hereinafter, embodiments of the present invention will be described in detail with reference to accompanying drawings.

Fig. 1 is an exploded perspective view of a chuck 100 for clamping a glass tube according to an embodiment of the present invention, and Fig. 2 is a side view schematically showing a state where a clamping means of the chuck for clamping the glass tube according the embodiment of the present invention shown in Fig. 1 is operated.

The chuck 100 for clamping the glass tube according to the embodiment of the present invention comprises a housing 110, a clamping means 120, a power transmitting means, and a clutch 160. A plurality of chucks are fixed to a rotary table 20 of a blowing machine at a predetermined interval.

The housing 110 is a cylindrical body with a through-hole formed therein and is installed on a relevant rotary table 20 in a state where the through-hole is oriented vertically. The clamping means 120 and the power transmitting means are installed on the housing 110. Bearing seats 116 and 117 on which bearings 116a and 117a are mounted are formed at upper and lower ends of the through-hole of the housing 110, respectively. That is, the first bearing seat 116 is formed at the lower end of the through- hole of the housing 110, and the second bearing seat 117 is formed at the upper end of the through-hole. Further, the first and second bearings 116a and 117a are fitted into the first and second bearing seats 116 and 117, respectively, such that outer peripheries of outer races of the first and second bearings 116a and 117a come into contact with inner peripheries of the first and second bearing seats 116 and 117, respectively. A guide portion 122 of the clamping means 120 to be described below is fitted into inner races of the bearings 116a and 117a. Meanwhile, a portion of a sidewall of the housing 110 between the first and second bearing seats 116 and 117 is partially cut away to form a gear engaging window 115 through which the interior of the housing communicates with the exterior thereof. The gear engaging window 115 is formed to connect the power transmitting means provided within the housing 110 to an external power source and may vary according to the type of connection of the power transmitting means to the power source. That is, the embodiment shown in the figures includes a gear 150, which will be described below, as the power transmitting means, and the gear engaging window 115 is formed to cause the gear 150 to be engaged with a driving gear 10 placed outside the housing 110. A housing fixing flange 111 for fixing the housing 110 to the rotary table 20 is formed to protrude from an outer periphery of the cylindrical sidewall of the housing 110. Accordingly, the housing 110 is fixed to the rotary table 20 by means of given bolts through housing fixing holes 112 in a state that the through-hole is oriented vertically and a bottom surface of the housing fixing flange 111 is in contact with an upper surface of the rotary table 20. At this time, the housing 100 is installed on the rotary table 20 such that the gear 150 provided within the housing 110 is engaged, through the gear engaging window 115, with the driving gear 10 placed outside the housing 110. Meanwhile, the chuck 100 for clamping the glass tube is heated with heat from a torch for heating the glass tube. Therefore, the bearings 116a and 117a may be deteriorated. To prevent the deterioration of the bearings, it is necessary to cool the chuck 100 for clamping the glass tube. To this end, a cooling water flow passage 113 through which cooling water passes is formed within the housing fixing flange 111. A water supply pipe connection port 113a to which an end of a given water supply pipe is connected is formed at an end of the cooling water flow passage. A drain pipe connection port (not shown) to which an end of a given drain pipe is connected is formed at the other end of the cooling water flow passage. That is, the cooling water flows into the cooling water flow passage 113 through the water supply pipe connection port 113a and is then drained through the drain pipe connection port.

The clamping means 120 is installed on the housing 110 to be rotated about a predetermined axis. A through-hole 123 is formed in the clamping means 120 along the axis. The clamping means 120 clamps an upper end of a glass tube 40 having a predetermined length so that a central axis of the glass tube 40 can be substantially aligned with the axis below the through-hole 123. The clamping means comprises a rotational member, a grasping portion 130, and a grasping portion-driving means 140. When external force exceeding a predetermined value is exerted on the clamping means by an external clamping release device 30, the grasping portion 130 of the clamping means 120 is outstretched to clamp the upper end of the glass tube 40 or release the clamped glass tube 40.

The grasping portion 130 and the grasping portion-driving means 140 are provided on the rotational member. In the embodiment shown in the figures, the rotational member comprises the guide portion 122, wherein the through-hole 123 extends by a predetermined length at the center of the guide portion along a predetermined axis that is a central axis of rotation of the clamping means 120, the grasping portion 130 is installed at a lower end of the guide portion 122, and the grasping portion-driving means 140 is installed around the guide portion 122 to move upward and downward. Referring to the figures, the grasping portion 130 is fixed to the lower end of the guide portion 122 in such a manner that the grasping portion 130 is bolted to a jaw base-fixing flange 124 provided at the lower end of the guide portion 122. However, the grasping portion 130 may be fixed to the lower end of the guide portion 122 by means of conventional methods such as welding. An upper end of the guide portion 122 is fitted into the inner races of the bearings 116a and 117a so that the guide portion 122 can be rotatably installed in the housing 110. At this time, in order to prevent the guide portion 122 from axially moving, the upper end of the guide portion 122 is exposed above the housing 110 and a fixing ring 170 is fixed to the upper end of the guide portion 122 by means of bolts 171.

The grasping portion 130 grasps the upper end of the glass tube 40 having a predetermined length so that the central axis of the glass tube 40 can be substantially aligned with the predetermined axis below the through-hole 123. A part of the grasping portion 130 for clamping the glass tube 40 is installed below the through-hole 123 of the rotational member. The grasping portion 13(3 comprises a jaw base 131 and jaws 134. The jaw base 131 is in the form of a disk with a through-hole therein and is installed at the lower end of the guide portion 122. A plurality of pivoting grooves 132 with a predetermined radial depth in which the jaws 134 can be pivotably mounted are formed at an outer periphery of the jaw base 131. The plurality of pivoting grooves 132 are arranged along the outer periphery of the jaw base 131 circumferentially at a predetermined interval. In the embodiment shown in the figures, three jaws 134 are installed for secure clamping and three pivoting grooves 132 are formed accordingly. Pivoting shaft insertion holes 132a into which both ends of a pivoting shaft 132b are inserted are formed on both sidewalls of each of the pivoting grooves 132 in a direction perpendicular to a plane including the axis. At this time, the pivoting shaft insertion holes 132a are formed such that the pivoting shafts 132b inserted into the pivoting shaft insertion holes 132a are located on the same circumference. The jaw 134 is installed in the pivoting groove 132 to pivot on the pivoting shaft 132b by inserting the pivoting shaft 132b into the pivoting shaft insertion holes 132a through a pivoting shaft hole 135 of the jaw 134. Accordingly, since the pivoting shaft 132b is orthogonal to the plane including the axis, the jaw 134 pivots in the plane including the axis. A lower end of the jaw 134 is used for clamping the glass tube 40. The jaw 134 pivots on the pivoting shaft 132b so that the lower end of the jaw can be puckered toward or outstretched away from the axis. In the embodiment shown in the figures, at least a portion of the jaw 134 protrudes above the jaw base 131 so that the jaw 134 can come into contact with a pressing surface 146 of a pressing plate 145 of the grasping portion-driving means 140 for pivoting the jaw 134. The jaw 134 takes the shape of a bow since the protruding portion and the lower end of the jaw are bent toward the axis angularly at a portion of the jaw adjacent to the pivoting shaft 132b. Accordingly, the shape of the jaw 134 and the shape and structure of the pressing plate 145 to be described later, which are shown in the figures, can be variously modified to pivot the jaw 134. At the protruding portion of the jaw 134, a roller 137 which comes into close contact with and rolls on the pressing surface 146 to be described later is installed to rotate about a shaft parallel with the pivoting shaft 132b. Further, the jaw 134 has a grasping recess 136 that is formed at the lower end thereof and corresponds to a round outer peripheral surface of the glass tube 40. The jaws 134 are pivotably mounted into the pivoting grooves 132 so that the rollers 137 of the jaws can come into contact with the pressing surface 146 and the grasping recesses 136 can be gathered below the through- hole 123 to define a circle corresponding to the outer peripheral surface of the glass tube 40. The operation for clamping the glass tube 40 by the jaws 134 will be described in detail together upon description of the grasping portion-driving means 140.

The grasping portion-driving means 140 is installed on the guide portion 122 to operate the jaws 134 such that the jaws 134 can be puckered toward or outstretched away from the axis. In the embodiment shown in the figures, the grasping portion-driving means comprises the pressing plate 145 that is installed on the guide portion 122 to be movable upward and downward by means of elastic force of the spring 143 and external force exceeding a predetermined value which is applied by the external clamping release device 30. The pressing plate 145 takes the shape of a disc with a hollow portion 147 into which the guide portion 122 is inserted. A top surface of the pressing plate 145 is a surface by which a lower end of the spring 143 is supported. A bottom surface of the pressing plate 145 is formed with the pressing surface 146 which the roller 137 comes into contact with and rolls on. Generally, the diameter of an upper side of the pressing surface 146 is larger than that of a lower side thereof, and an outer peripheral surface of the pressing plate 146 is formed to be a gently curved concave surface. That is, the radius of the pressing surface 146 gradually decreases toward the lower side thereof, and a generator of the pressing surface forms a curved concave line. The pressing plate 145 is fitted around the guide portion 122 to move upward and downward along the guide portion 122. Meanwhile, an annular stopper 141 is fitted around an upper portion of the guide portion 122 and fixed thereto by means of fixing bolts 141a. Further, the coil type compression spring 143 is installed below the stopper 141. One end of the spring 143 is supported by the stopper 141 and the other end supports the upper surface of the pressing plate 145 so that elastic force of the spring 143 can be applied downward to the pressing plate 145. As described above, the pressing plate 145 installed below the guide portion 122 moves downward along the guide portion 122 by means of the elastic force of the spring 143 and also moves upward along the guide portion 122 by means of the upward external force applied to an outer edge of the lower surface of the pressing plate 145 by the clamping release device 30. Referring to the figures, when the pressing plate 145 moves downward and exerts force on the roller 137, the lower ends of the jaws 134 which pivot on the pivoting shafts 132b below the jaw base 131 are puckered toward the axis. When the pressing plate 145 moves upward by means of external force exceeding a predetermined value, the lower ends of the jaws 134 pivot to be outstretched away from the axis due to their dead weight. The foregoing will be described in greater detail with reference to Fig. 3 that schematically shows a principle of pivoting of the jaw 134. When the pressing plate 145 moves from the uppermost side to the lowermost side, the jaw 134 pivots by means of force applied in a direction of a normal at a contact point of the generator 146a of the pressing surface 146 and the circumference of the roller 137 while the roller 137 rolls upward along the generator of the pressing surface 146. When the pressing plate 145 moves from the lowermost side to the uppermost side, the jaw 134 pivots due to its dead weight while the roller 137 rolls upward along the generator 146a in a state where the roller 137 is in contact with the pressing surface 146. Particularly, in order to ensure the smooth pivoting of the jaw 134 as described above, the contour of the pressing surface 146 should be established such that the normal at the contact point of the generator 146a of the pressing surface 146 and the circumference of the roller 137 is located outside a circle on which the pivoting shaft 132b is installed and the normal is placed at a skew position with respect to the pivoting shaft 132b. Further, it is preferred that when the jaw 134 clamps the upper end of the glass tube 40, the center of gravity 148a of the jaw 134 be located inside a circle on which the pivoting shaft 132b is installed. Accordingly, due to the force 149 applied to the jaw 134 at the contact point of the generator 146a of the pressing surface and the circumference of the roller 137, the lower end of the jaw 134 pivots to be puckered toward the axis and subsequently to clamp the upper end of the glass tube 40. Due to the gravity 148 acting on the center of gravity 148a, the jaw 134 pivots so that the lower end thereof is outstretched away from the axis to release the clamped glass tube 40.

The power transmitting means is installed at the housing 10 and transmits power for rotating the clamping means 120. In the embodiment shown in the figures, the power transmitting means comprises the gear 150. The gear 150 is a spur gear having a central hole into which the guide portion 122 is fitted, and teeth formed at an outer periphery thereof. The gear 150 is fitted around the guide portion 122 and placed within the housing 110. At this time, a portion of the teeth of the gear 150 is exposed through the gear engaging window 115 so that the gear can be engaged with the driving gear 10 through the gear engaging window 115. As described above, the gear 150 engaged with the driving gear 10 receives rotational force from the driving gear 10 and transmits it to the guide portion 122 through a clutch 160. The clutch 160 receives the rotational force from the power transmitting means and transmits the power to the guide portion 122, and is constructed such that the power transmitted to the guide portion 122 can be cut off if external force exceeding a predetermined value is applied to the clamping means 120. In order to achieve this function, the clutch 160 can be disposed at a proper position on a power transmitting path from a given power source to the guide portion 122. The figures show an embodiment in which the clutch 160 is installed between the power transmitting means and the rotational member, i.e. between the gear 150 and the guide portion 122. As for the clutch 160, a one-way clutch may be used if the clamping means 120 rotates in one direction. In the figures, there is shown an embodiment that employs a friction clutch using friction force generated by a contact surface where a friction pad 163 rotating integrally with the gear comes into the outer periphery of the guide portion 122. The friction clutch is installed in each of clutch mounting holes 153 formed at the gear, and comprises an adjuster screw 161, a friction pad pressing spring 162 and the friction pad 163. The clutch mounting holes 153 are a plurality of holes that radially extend through an outer wall of the gear 150 and an inner wall of a hole into which the guide portion 122 is inserted. The figures show that three clutch mounting holes 153 are formed at a predetermined interval in a circumferential direction of the gear 150. If necessary, much more clutch mounting holes 153 may be formed. The adjuster screw 161, the friction pad pressing spring 162 and the friction pad 162 are inserted into each of the clutch mounting holes 153 in this order from the outside to the inside in a radial direction. The adjuster screw 161 is installed to adjust the magnitude of elastic force of the friction pad pressing spring 162. To this end, the adjuster screw 161 is inserted into the clutch mounting hole 153 at the outermost side thereof in the radial direction so that it can move radially inward and outward in the clutch mounting hole 153. The radially inward and outward movement of the adjuster screw 161 is achieved by screwing and unscrewing the adjuster screw. The friction pad pressing sprig 162 is a compression coil spring that is located between the adjuster screw 161 and the friction pad 163 and applies elastic force to the friction pad 163 toward the axis. That is, the friction pad pressing spring 162 is inserted into the clutch mounting hole 153 such that a radially outer end of the friction pad pressing spring is supported by a radially inner end of the adjuster screw 161 and a radially inner end of the friction pad pressing spring supports a radially outer end of the friction pad 163, thereby applying the elastic force to the friction pad and bringing a radially inner end of the friction pad 163 into close contact with the outer peripheral surface of the guide portion 122. The friction pad 163 is inserted into and mounted on a radially inner side of the clutching mounting hole 153 in a state where the radially outer end of the friction pad 163 is supported by the radially inner end of the friction pad pressing spring 162 such that the radially inner end of the friction pad 163 is in close contact with the outer peripheral surface of the guide portion 122. As described above, since the friction pad 163 receives the elastic force of the friction pad pressing spring 1632 and then comes into contact with the outer peripheral surface of the guide portion 122, friction is generated at a contact portion between the friction pad 1632 and the guide portion 122. Accordingly, as the gear 150 rotates, the guide portion 122 also rotates. Meanwhile, the magnitude of the friction force generated at the contact portion between the guide portion 122 and the friction pad 163 is adjusted by the radially inward or outward movement of the adjuster screw 161. If a torque with a magnitude larger than that of a torque generated due to the friction force is applied to a portion between the guide portion 122 and the gear 150, a slip occurs at the contact surface between the friction pad 1632 and the guide portion 122. That is, even though the gear 150 receives the rotational force from the driving gear 10 and then rotates, the friction clutch is slipped if a torque exceeding a predetermined value is applied to the guide portion 122. Therefore, relative rotation occurs between the guide portion 122 and the gear 155. Accordingly, in a case where the clamped glass tube 40 should be rotated to be uniformly heated or subjected to a blowing process for obtaining a uniform shape, the friction clutch transmits the rotational force so that the glass tube 40 can be rotated together with the guide portion 122. Further, in a case where the grasping portion 130 is outstretched to supply the clamping means 120 with a glass tube 40 or to release a clamped glass tube from the clamping means 120, the friction clutch serves to cut off the rotational force using a slip generated therein. Meanwhile, the torque applied to the portion between the guide portion 122 and the gear 150 such that a slip occurs in the friction clutch is generated by external force exceeding a predetermined value, which is applied to the bottom surface of the pressing plate 145 by the clamping release device 30. That is, the external force exceeding the predetermined value that upward pushes the pressing plate 145 causes the pressing plate 145 to move upward, and the friction force generated at the contact portion of the clamping release device 30 and the pressing plate 145 becomes a torque applied to the guide portion 122. The torque stops the guide portion 122, and a slip occurs in the friction clutch provided between the guide portion 122 and the gear 150.

Fig. 4 is a sectional view showing a state where a tube glass 400 mounted on the chuck 100 for clamping the glass tube according to the embodiment of the present invention shown in Fig. 1 is subjected to a blowing process to be formed into a bulb. The glass tube 40 of which a dome portion 40b has been heated by a predetermined torch is located in a mold 50 in a state where the glass tube is clamped by the chuck 100 such that an opening of a flare portion 40a is aligned with a lower opening of the through-hole 123. Then, an air injection nozzle 60a fixed a distal end of an air injection tube 60 is inserted into the glass tube from an upper opening of the through-holes 123. When the air injection nozzle 60a passes through the through-hole 123 and reaches the opening of the flare portion 40a of the glass tube 40, compressed air is injected into the glass tube 40 through the air injection tube 60 and the air injection nozzle 60a. When air is injected into the glass tube 40 in such a way, the dome portion 40a of the glass tube 40 is subjected to the blowing process to take the same shape, i.e. a bulb, as the mold. After the aforementioned blowing process is completed, the mold 50 is opened and the bulb clamped on the chuck 100 is moved to the next process by the rotation of the rotary table 20. When the clamping of the bulb by the clamping means 120 is released by the operation of the clamping release device 30, the glass tube is separated from the clamping means 120 and then moved to a predetermined annealing apparatus for heat treatment. Fig. 5 is an exploded perspective view of a chuck 200 for clamping a glass tube according to another embodiment of the present invention.

The chuck 200 for clamping the glass tube according to the other embodiment of the present invention shown in Fig. 5 comprises a housing 210, a power transmitting means 250 and a clutch 260 in the same manner as the embodiment shown in Fig. 1. The chuck 200 is almost identical to the embodiment shown in Fig. 1 in view of their structures and cooperative relationships. Therefore, a clamping means 220 that is a main feature of the other embodiment of the present invention will be described in detail below. The clamping means 220 of the chuck 200 according to the other embodiment of the present invention is installed on the housing 210 to rotate about a predetermined axis. The clamping means 220 is formed with a through-hole 223 along the axis, and clamps an upper end of the glass tube 40 having a predetermined length such that a central axis of the tube glass 40 is substantially aligned with the predetermined axis below the through-hole 223. The clamping means comprises a rotational member, a grasping portion 230 and a grasping portion-driving means 240. Further, when external force exceeding a predetermined value is applied to the clamping means 220 by an external clamping release device 31, the grasping portion 230 of the clamping means 220 is outstretched to clamp an upper end of a glass tube 40 or release a clamped glass tube 40.

The grasping portion 230 and the grasping portion-driving means 240 are installed on the rotational member. The rotational member comprises a guide portion 222 in the same manner as the rotational member of the embodiment shown in Fig. 1.

The grasping portion 230 grasps the upper end of the glass tube 40 having a predetermined length so that the central axis of the glass tube 40 can be substantially aligned with the predetermined axis below the through-hole 123. The grasping portion comprises a jaw base 231 and jaws 234 and 235. The jaw base 231 is in the form of a disk with a through-hole therein and is installed at a lower end of the guide portion 222 to be concentric with the through-hole 223 of the guide portion 222. A first jaw 234 and a second jaw 235 that are in pairs are installed on the bottom of the jaw base 231 to be symmetric with respect to the axis and to pivot on a plurality of pivoting shafts 234a and 235a, which are disposed at a predetermined interval along the same circumference at an outer periphery of the jaw base 221 and arranged parallel with the axis, such that one ends of the jaws can be puckered toward or outstretched away from the axis. This will be described in greater detail with reference to this figure. Hinge shaft holes (not shown) are formed through the jaw base 231 at positions thereon symmetric with respect to the axis. The first pivoting shaft 234a and the second pivoting shaft 235a are rotatably fitted into the respective hinge shaft holes. At this time, each of the first and second pivoting shafts 234a and 235a is mounted such that both ends thereof protrude beyond top and bottom surfaces of the jaw base 231. An end of the first jaw 234 is fixed to a lower end of the first pivoting shaft 234a to pivot integrally with the first pivoting shaft 234a. An end of the second jaw 235 is fixed to a lower end of the second pivoting shaft 235a to pivot integrally with the second pivoting shaft 235a. That is, the first and second jaw 234 and 235 are mounted on the bottom of the jaw base 231 such that the other ends opposite to the ends fixed to the pivoting shafts 234a and 235a face each other. The glass tube 40 is grasped by the facing portions. Further, in order to securely grasp the glass tube 40, a portion of the second jaw 235 by which the glass tube 40 is grasped is formed with a grasping concave recess 236 corresponding to an outer peripheral surface of the glass tube 40. Although the figure shows an embodiment in which the grasping recess is formed in only the second jaw 235, the present invention is not limited thereto. That is, all of the jaws may be formed with grasping recesses. Meanwhile, the first and second jaws 234 and 235 are installed on the first and second pivoting shafts 234a and 235 a, respectively, to be spaced apart from the bottom surface of the jaw base 231 by a predetermined distance, so that the upper end of the glass tube 40 can be clamped in a state where the upper end of the glass tube protrudes beyond upper surfaces of the first and second jaws 234 and 235 by a predetermined length.

The grasping portion-driving means 240 is installed above the jaw base 231 to operate the jaws 234 and 235 such that they are puckered toward or outstretched away from the axis. In the embodiment shown in the figure, the grasping portion-driving means 240 is a link device comprising driving link rods 241 and 243 that pivot integrally with the jaws 234 and 235, respectively, and a connecting link rod 242 for connecting the driving link rods 241 and 243 to each other so that the driving link rods 241 and 243 can pivot simultaneously. The driving of the grasping portion-driving means 240 is achieved by means of elastic force of a spring 247 to be described below and external force exceeding a predetermined value that is applied to the link device by the external clamping release device 31. One end of the first driving link rod 241 is fixed to an upper end of the first pivoting shaft 234a, and an end of the connecting link rod 242 is rotatably connected to the other end of the first driving link rod 241. The first driving link rod 241 rotates integrally with the first pivoting shaft 234a thereabout. The end of the connecting link rod 242 is rotatably connected to the other end of the first driving link rod 241 and the other end of the connecting link rod 242 is rotatably connected to an end of the second driving link rod 243. Therefore, the connecting link rod 242 is interlocked with the first and second driving link rods 241 and 243 so that it can simultaneously pivot together with the first and second driving link rods 241 and 243. A proper portion between both ends of the second driving link rod 243 is fixed to an upper end of the second pivoting shaft 235 a, so that the second driving link rod 243 a can pivot integrally with the second pivoting shaft 235 a thereabout. Further, the other end of the second driving link rod 243 has a projection with a predetermined length. The projection is connected to one side of the spring 247 for applying elastic force in one direction of the pivoting movement of the driving link rods 241 and 243 and the connecting link rod 242. The other side of the spring 247 is connected to a spring support pin 248 fixed to the top surface of the jaw base 231 to apply elastic force to the second driving link road 243 in one direction of the pivoting movement, thereby maintaining a state where the first and second jaws 234 and 235 clamp the glass tube 40 via the driving link rods 241 and 243 and the connecting link rod 242.

Figs. 6 (A) and (B) conceptually show the operation of the clamping means 200 of the chuck 200 for clamping the glass tube according to the other embodiment of the present invention shown in Fig. 5. Due to the restoring force of the tension spring 247, the driving link rods 241 and 243 and the connecting link rod 242 pivot toward the second driving link rod 243. Accordingly, the first and second jaws 234 and 235 pivot and are puckered toward the axis to clamp the glass tube 40. When the external clamping release device 31 pushes a connection portion where the connecting link rod 242 and the second driving link rod 243 are connected to each other toward the first driving link rod 241 to exert external force thereon, the spring 247 is extended, the second driving link rod 243 pivots on the second pivoting shaft 235 a toward the first driving link rod 241, and the second jaw 235 pivots away from the glass tube 40, i.e. away from the axis. As described above, when the second driving link rod 243 pivots, the connecting link rod 242 is translated. Subsequently, the first driving link rod 241 also pivots on the first pivoting shaft 234a, and the first jaw 243 pivots away from the glass tube 40. Accordingly, the first and second jaws 234 and 235 are outstretched away from the axis so that the clamped state of the glass tube can be released. Meanwhile, the external force that the clamping release device 31 applies to the connection portion where the connecting link rod 242 and the second driving link rod 243 are connected to each other causes a slip in the clutch 260 installed between the guide portion 222 and a driven gear 250. Accordingly, when the clamping of the clamping means 250 is released, the rotation of the guide portion 222 is stopped.

The process of performing the blowing of the glass tube using the chuck 200 according to the other embodiment of the present invention shown in Fig. 5 is substantially identical to the process of performing the blowing of the glass tube using the chuck 100 according to the embodiment of the present invention shown in Fig. 4.

The chuck 100 or 200 for clamping the glass tube according to the present invention constructed as above is used in a blowing machine as follows. The chucks for clamping glass tubes are arranged at a predetermined interval along a periphery of a rotary table of the blowing machine so that the gears of the chucks can be engaged with the driving gear. Accordingly, the chucks for clamping the glass tubes rotate together with the rotary table and the gears simultaneously rotate by means of the rotation of the driving gear. Meanwhile, a glass tube is supplied to the chuck in a state where the grasping portion of the clamping means of the chuck is outstretched away from the axis by means of external force exceeding a predetermined value, which is applied by the external clamping release device. Then, the glass tube is clamped when the grasping portion is puckered. With the rotation of the rotary table, the glass tube clamped on the chuck in such a way is heated and then subjected to the blowing process. At this time, the glass tube rotates integrally with the rotational member that rotates through the friction clutch. A bulb produced through the blowing process is separated from the chuck when the clamping of the clamping means is released and the grasping portion is outstretched away from the axis by means of external force exceeding a predetermined value that is applied by the clamping release device. Meanwhile, if the clamping release device applies the external force to the clamping means, a slip occurs in the friction clutch provided between the gear and the guide portion, resulting in stop of the rotation of the guide portion.

Industrial Applicability The chuck for clamping a glass tube according to the present invention constructed as above is suitable for a blowing machine in which a glass tube preform that is cut to have a predetermined length and both ends thereof are formed into a dome portion and a flare portion, respectively, is first produced and the glass tube preform is then loaded to be subjected to a blowing process so that it can be formed into a bulb. That is, the present invention has an advantage in that a glass tube having a predetermined length can be clamped on the bottom of the chuck, the clamped glass tube can be rotated and air can be injected into the glass tube.

It is intended that the embodiments of the present invention described above and illustrated in the drawings should not be construed as limiting the technical spirit of the present invention. The scope of the present invention is defined only by the appended claims. Those skilled in the art can make various changes and modifications thereto without departing from its true spirit. Therefore, various changes and modifications obvious to those skilled in the art will fall within the scope of the present invention.

Claims

1. A chuck for clamping a glass tube, which comprises: a housing; a clamping means that is installed on the housing to be rotatable about a predetermined axis, is formed with a through-hole with a predetermined diameter along the predetermined axis, and has a grasping portion for clamping an upper end of the glass tube below the through-hole such that a central axis of the glass tube is substantially aligned with the predetermined axis; a power transmitting means installed in the housing to transmit power for rotating the clamping means; and a clutch for receiving the power from the power transmitting means and transmitting the received power to the clamping means, whereby when external force exceeding a predetermined value is applied to the clamping means, the grasping portion of the clamping means is outstretched to clamp the upper end of the glass tube or release a clamped glass tube and the clutch cuts off the power transmitted to the clamping means.

2. The chuck according to Claim 1, wherein the clamping means further comprises a rotational member that rotates by receiving the power from the clutch and is formed with the through-hole, and a grasping portion-driving means installed on the rotational member to pucker or outstretch the grasping portion, clamping parts of the grasping portion for clamping the glass tube are installed below the through-hole of the rotational member, and the external force exceeding the predetermined value is applied to the grasping portion-driving means.

3. The chuck according to Claim 2, wherein the clutch is installed between the power transmitting means and the rotational member.

4. The chuck according to Claim 2, wherein the rotational member comprises a guide portion formed by extending an outer periphery of the through-hole by a predetermined length along the axis, the grasping portion comprises a disk-shaped jaw base that has a through-hole formed therein and is installed at a lower end of the guide portion of the rotational member to be concentric with the through-hole of the rotational member, pivoting shafts disposed at a predetermined interval along the same circumference at an outer periphery of the jaw base and arranged perpendicularly to a plane including the axis, and a plurality of jaws pivotably mounted at the respective pivoting shafts such that at least a portion of each of the jaws protrudes above the jaw base, the grasping portion-driving means comprises a pressing plate that is installed to be movable vertically along the guide portion and has a pressing surface provided at a bottom surface thereof to come into contact with the protruding portions of the jaws so that the jaws can pivot, a spring installed at the guide portion such that a lower side of the spring is in contact with a top surface of the pressing plate, and a stopper that is in contact with an upper side of the spring and fixedly installed at the guide portion, and the external force exceeding the predetermined value is applied upward to the bottom surface of the pressing plate.

5. The chuck according to Claim 4, wherein the center of gravity of each of the jaws is located inside the concentric circumference on which the pivoting shafts are installed.

6. The chuck according to Claim 5, wherein the number of the jaws is three, and the protruding portion of each of the jaws is provided with a roller that comes into contact with and rolls on the pressing surface.

7. The chuck according to Claim 6, wherein the pressing surface of the pressing plate has a radius which gradually decreases toward the lower end of the guide portion, and a normal at a point where the roller comes into contact with the pressing surface passes outside the concentric circumference on which the pivoting shafts are installed.

8. The chuck according to Claim 2, wherein the rotational member comprises a guide portion formed by extending an outer periphery of the through-hole by a predetermined length along the axis, the grasping portion comprises a disk-shaped jaw base that has a through-hole formed therein and is installed at a lower end of the guide portion of the rotational member to be concentric with the through-hole of the rotational member, pivoting shafts disposed at a predetermined interval along the same circumference at an outer periphery of the jaw base and installed parallel with the axis, and a plurality of jaws having one ends fixed to lower ends of the respective pivoting shafts so that the jaws can pivot integrally with the pivoting shafts, the grasping portion-driving means comprises a plurality of driving link rods having one ends fixed to upper ends of the respective pivoting shafts to pivot integrally with the respective pivoting shafts, the end of at least one of the driving link rods being provided with a projection extending in a direction opposite to the other end of the relevant driving link rod, connecting link rods each of which has both ends connected to the other ends of two driving link rods to pivot on axes parallel with the pivoting shafts, and a spring of which one side is connected to the projection of the relevant driving link rod and the other side is connected to an edge of the jaw base, and the external force exceeding the predetermined value is applied horizontally to at least one of connection portions of the driving link rods and the connecting link rods.

9. The chuck according to Claim 8, wherein the number of the jaws is two, and a grasping recess is formed in at least one of ends of the jaws by which the tube glass is clamped.

10. The chuck according to any one of Claims 4 to 9, wherein the power transmitting means is a gear fitted around the guide portion, and the clutch is installed between the gear and the guide portion.

11. The chuck according to Claim 10, wherein the housing is provided with a cooling water flow passage in which cooling water flows.

12. The chuck according to Claim 11, wherein the clutch is a friction clutch including a friction pad that is installed in the gear to be in contact with an outer peripheral surface of the guide portion and rotates integrally with the gear.

13. The chuck according to Claim 12, wherein the gear is formed with at least three clutch mounting holes that penetrate through radially inner and outer walls of the gear and are disposed circumferentially at a predetermined interval, and the friction clutch comprises: an adjuster screw provided on a radially outer side in each of the clutch mounting holes to move radially inward and outward within the clutch mounting hole, a friction pad pressing spring inserted into each of the clutch mounting holes such that a radially outer end of the friction pad pressing spring is supported by a radially inner end of the adjuster screw, and a friction pad mounted on a radially inner side in each of the clutch mounting holes such that a radially outer end of the friction pad is supported by a radially inner end of the friction pad pressing spring and a radially inner end of the friction pad comes into contact with the outer peripheral surface of the guide portion.

14. The chuck according to Claim 10, wherein the clutch is a friction clutch including a friction pad that is installed in the gear to be in contact with an outer peripheral surface of the guide portion and rotates integrally with the gear.

15. The chuck according to Claim 14, wherein the gear is formed with at least three clutch mounting holes that penetrate through radially inner and outer walls of the gear and are disposed circumferentially at a predetermined interval, and the friction clutch comprises: an adjuster screw provided on a radially outer side in each of the clutch mounting holes to move radially inward and outward within the clutch mounting hole, a friction pad pressing spring inserted into each of the clutch mounting holes such that a radially outer end of the friction pad pressing spring is supported by a radially inner end of the adjuster screw, and a friction pad mounted on a radially inner side in each of the clutch mounting holes such that a radially outer end of the friction pad is supported by a radially inner end of the friction pad pressing spring and a radially inner end of the friction pad comes into contact with the outer peripheral surface of the guide portion.

16. The chuck according to any one of Claims 1 to 3, wherein the housing is provided with a cooling water flow passage in which cooling water flows.