Work table for pattern matching

Abstract: The present invention relates to a work table on which plural sheets of cloth are piled with the pattern kept matched. Generally, after the pattern is matched, the cloth is cut according to the sewing pattern. Plural electromagnets (46) are disposed on the work table that can be magnetized/demagnetized by turning ON/OFF of the switches. By magnetizing the electromagnets during the pattern matching operation, pin seats (26) of pin devices (24) placed on the electromagnets are firmly attracted to the magnets. Thus, sheets of cloth can be laid one upon another as guided by needles (28) of the pin devices for pattern matching. When the pattern matching is completed, the electromagnets are demagnetized to release the seats from the electromagnets, and air is injected against the cloth through vents (4) provided on the table to facilitate transportation of the piles of cloth.

Description: The present invention relates to an improvement of a work table for pattern matching which is used when plural sheets of cloth with a pattern are piled and cut simultaneously to be sewn as clothes while the pattern on each sheet matching with the pattern on other sheets of cloth. Prior Art A prior art pattern matching table includes a table for placing a cloth material provided with plural through holes, a means for vertically reciprocating needles attached to piston rods through said through holes by the action of a fluid cylinder, a cylindrical operating unit which contain the needles therein and which is provided beneath said through holes in a freely reciprocating manner, a means for operating said reciprocating means stepwise via a timer relay and an electromagnetic valve by actuating a micro-switch by lowering said cylindrical operating unit, and a projector means which is movably provided above said work table for the material cloth and which indicates the position of the needles and pattern matching by projection (Jap. Pat. Publication No. Sho 61-35306). According to another example of the prior art, a base is interposed between two layers of thin material placed on a work table, and needles are arranged on the base in accordance with the pattern of the material cloth. Plural sheets of the material cloth are piled on the work table as guided by the needles. When the pattern is matched, the cloth is moved together with the thin layers and the base for cutting (Jap. Pat. Appln. Laid-open No. Sho 62-276074). The work table according to Jap. Pat. Pub. No. Sho 61-35306 is advantageous in that the needles are firmly fixed on the table when the pattern is matched. On the other hand, when plural sheets of cloth are transferred to a cutting table after the pattern matching, the pattern may inconveniently become out of matching as the needles are pulled out. In the case of Laid-open Application No. Sho 62-276074, although the piled sheets of material cloth can be easily transported with the pattern held matched by the needles, needles may become displaced during the actual operation of pattern matching as the needles are merely interposed between the thin materials, and pattern matching tends to become inaccurate. US 4,209,165 discloses a magnetic work table including a plurality of pin devices arranged to extend through apertures provided in the work surface of the work table, the pin devices including magnetic seats arranged to engage with the underside of the work surface. The present invention was contrived in view of the foregoing situations in the prior art, and aims at providing a work table for pattern matching which enables the needles to be firmly held in place during the pattern matching, and which prevents the material cloth from becoming displaced when transported to another table after the pattern matching. Another object of the present invention is to provide a work table for pattern matching which enables smooth transportation of the material cloth after pattern matching. According to the present invention there is provided a working surface and a plurality of needles for engagement in cloth layers in use on said working surface, said needles being parts of respective pin devices each pin device having a magnetic seat presented to said working surface and from which the respective needle is upstanding, said table being characterized in that the pin devices are movable on said working surface, and said table includes electromagnet means energisable to retain magnetically each pin device relative to said working surface. Air vents are preferably provided on the work table at a predetermined interval and compressed air is introduced into the vents from an air supply means to facilitate transportation of the cloth after the pattern is matched. In use, the pins having needles are placed on the work table according to the pattern of the material cloth and then the electromagnets are magnetically switched ON to firmly hold the pins on the table. Plural sheets of cloth are piled on one after another as guided by the marking needles of the pins fixed on the table for pattern matching. When the pattern matching is completed, the switch is turned OFF to demagnetize the electromagnets and to release the pins from fixation. After the pins are released, the cloth is transported together with the pins to a place designated for cutting. By injecting compressed air through the air vents provided on the work table, the friction coefficient between the cloth and the work table is decreased and transportation of the cloth is facilitated. The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a work table according to a first embodiment of the invention; Fig. 2 is a front sectional view of part of the work table of Fig. 1; Fig. 3 is a perspective view of a pin; Fig. 4 is a time chart to show how the electric current is supplied to the control unit; Fig. 5 is a flow chart of the pattern matching operation; Fig. 6 is a perspective view of a work table according to a second embodiment; Fig. 7 is a cross-section along the line VII-VII of Fig. 6; and Fig. 8 is a cross-section along the line VIII-VIII of Fig. 6. The present invention will now be described in more detail referring to the preferred embodiments shown in the attached drawings. In the figures, the reference numeral 1 denotes a work table according to the present invention, on which a surface board 2 made of electromagnetic material is mounted. Plural air vents 4 are opened on the surface board 2 at a regular interval in a grid formation. The lower portion of the surface board 2 is covered by a casing 6 as shown in Fig. 2, and the casing 6 communicates with a duct 8. Inside the duct 8 are disposed a fan 12 which is actuated when supplied with electric power from a control unit 10 for feeding the air, plural partitions 14 which direction of the air feed for uniform air supply, and a mesh 16 provided above said partitions 14 which enables the air supply to be still more uniform. Said fan 12 introduces air from an air intake port 18 in the duct and injects the air through the vents 4 onto the surface board. The surface board 2 is connected with one end of a U-shaped ferromagnetic core 20 substantially at the center of the board, and an insulated conductor 22 such as coil is wound about the core 20. The insulated conductor 22 is connected to the control unit 10, and a plate electromagnet is formed by the control unit 10, the core 20, the insulated conductor 22 and the magnetic surface board 2. Amount of current to be applied to the coil may differ depending on the number of coil windings, but is determined by the attraction force of the electromagnets. The reference numeral 24 denotes a pin which is to be placed on the surface board 2 constituting the work table 1. Each pin 24 comprises a disk-like seat 26 and a needle 28 vertically bonded on the seat 26. The seat 26 is preferably made of magnetic material such as iron so that it can be attracted to the surface board 2 by the effect of the magnetic field. The needle is preferably such that it can penetrate cloths but will not leave a large hole on the cloth 29. The thickness of the needle is preferably in the range of from 0.5 to 1.5 mm, and the length in the range of from 3 to 10 cm. The control unit 10 supplies electric power to the fan 12 and the electromagnets, as shown in Fig. 2, and is switched ON/OFF by switches 30 and 32 provided on the unit 10. As shown in Fig. 4, the present invention is so constructed that a small amount of current is supplied in the reverse direction for a predetermined period of time after the power supply is suspended upon magnetization of the plate magnet in order to avoid residual magnetism from being briefly left on the surface board 2. This is to prevent residual magnetism from geing generated on the surface board 2 when the cloth is transported since the seat 24 can be easily attracted to the board 2 by a trace magnetism. Referring now to the flow chart shown in Fig. 5, plural number of seats 24 are placed on the work table 1 in accordance with the pattern of the cloth while the switch 30 for the magnet and the switch 32 for the fan are turned off. When the seats 24 are placed, the switch 30 for the magnet is turned ON to cause the seats 24 to be attracted to and firmly fixed on the surface board 2. As the seats 24 are fixed, the cloth is unrolled while registering the pattern with the needles 28 and piled in plural layers. When the pattern is matched, the switch 30 for the magnet is turned OFF to demagnetize the magnets, and the fan switch 32 ls subsequently turned ON. Air is sucked from the intake port 18 by the action of the fan 12, and the air regulated in pressure by the partitions 14 and the mesh 16 is guided toward the bottom of the surface board 2 via the duct 8 and the casing 6. Air is then injected on the cloth via the air vents 4 perforated on the surface board 2. As a result, the friction coefficient between the surface board 2 and the cloth is decreased, and the cloth 29 can be easily slid on the table to be transported. Referring now to Figs. 6 through 8 which show another embodiment of the present invention, the work table 1 comprises aluminum frame members 36 having a U-shape section that are disposed in parallel arrangement at a given interval to provide grooves 38 for receiving electromagnets. For example as shown in Fig. 7, plate members 42 are bonded on a rectangular frame member 40 at a given interval, and base plates 44 are disposed on the plate members 42. A U-shaped aluminum frame member 36 each is suspended between the base plates 44, and the interval space between the frame members 36 is utilized as the groove 38 for receiving an electromagnet. Air vents 4 are provided at a predetermined interval on each aluminum frame member 36 in the longitudinal direction, and air is injected into the air vents 4 under a uniform pressure from the fan 12, as in the case of the embodiment 1. A pair of electromagnets 46 is arranged in each groove 38 at a predetermined interval in the longitudinal direction, as shown in Fig. 8, and a metal plate 48 made of ferromagnetic material is attached to the magnetic pole of each electromagnet 46. The distance between each metal plate 48 is approximately equal to 1/2 of the diameter of the seat 26 of the pin 24. Each electromagnet 46 is wired in parallel connection with the control unit 10 which supplies the power. It is noted that the plate members 42 located on both sides of the work table are associated with one of side plates 40a which constitutes the frame member 40, respectively. Legs 50 are attached to the side plates 40a. With the work table having the above described construction, air is injected against the cloth via the vents 4 provided on the aluminum frame members 36, but not from the grooves 38 where the electromagnets 46 are disposed. According to this second embodiment, the cloth is first placed on the work table 1, and the needles 28 are driven into the cloth at positions suitable for pattern matching. The seats 24 are then placed on the metal plate 48 before the switch on the control unit 10 for magnetization is turned ON to magnetically fix the seats on the metal plate 48. Another sheet of cloth is laid over the first sheet while matching the pattern as guided by the needles 28 on the seats 24. When predetermined number of sheets of cloth are piled, the electromagnets 46 are demagnetized (by turning the switch OFF for magnetization) and the switch for demagnetization is turned ON. The fan 12 is also switched ON to reduce the friction coefficient between the cloth and the work table. This enables an operator to easily transport the piles of cloth carrying the pins therewith and to cut the cloth with the pattern kept matched. Although the electromagnets are placed on the entire surface board or in all of the grooves for receiving the electromagnets in the above-mentioned embodiments, the present invention is in no way limited by such construction. It is possible to use non-magnetic material such as wood for the surface board and the control units may be disposed on the surface board in a grid, straight line or in any other arbitrary arrangement so that electromagnets that can be magnetized/demagnetized by turning ON/OFF of the switches can be embedded. Field of Industrial Application As has been described in the foregoing, the work table for pattern matching according to the present invention can hold the needles which keep the pattern matched firmly in place during the pattern matching operation by the magnetizing action of the electromagnets and the needles may be released from the work table by demagnetizing the electromagnets after the matching operation, so that the pattern matching operation is facilitated and the cloth can be transported to another place for cutting while carrying the pins which keep the pattern matched.

Claims: A work table for pattern matching, comprising a working surface (2) and a plurality of needles (28) for engagement in cloth layers in use on said working surface (2), said needles (28) being parts of respective pin devices (24) each pin device (24) having a magnetic seat (26) presented to said working surface (2) and from which the respective needle (28) is upstanding, said table being characterized in that the pin devices are movable on said working surface (2), and said table includes electromagnet means (20, 22; 46) energisable to retain magnetically each pin device (24) relative to said working surface (2). A work table as claimed in Claim 1 characterized in that said electromagnetic means comprises a surface board (2) of magnetic material magnetically coupled to an electromagnetic core (20) upon which an electromagnetic winding (22) is positioned. A work table as claimed in Claim 1 characterized in that said electromagnetic means comprises a plurality of individual electromagnets (46, 48) spaced apart over said working surface. A work table as claimed in any one of Claims 1 to 3 characterized in that air vents (4) are provided in said working surface and there is provided fan means for generating an air flow through said vents. A work table as claimed in Claim 4 characterized in that said fan means delivers air under uniform air pressure to said vents. A work table as claimed in any one of Claims 1 to 5 characterized by electrical switch means controlling energisation of said electromagnet means.

Inventors: KAWASAKA SHOZO, KAWASAKA, SHOZO
Applicants: TOUHAKU CO LTD, TOUHAKU CO. LTD.
Application year: 1990
Main classification: A41H15
IPC codes: A41H15