ADHESIVE APPLICATION DEVICE, APPARATUS FOR PRODUCING LAMINATED STEEL CORE HAVING THE ADHESIVE APPLICATION DEVICE, AND METHOD FOR PRODUCING LAMINATED STEEL CORE

The present invention provides an adhesive application device configured to apply a necessary and sufficient amount of an adhesive to a thin steel strip without causing the problem of increase in the equipment cost. The present invention also provides an apparatus for producing a laminated steel core having the adhesive application device. The present invention further provides a method for producing a laminated steel core. The adhesive application device comprises adhesive application devices (3), (4) that are integrated into a single process, wherein the adhesive application devices (3), (4) are configured to independently apply an adhesive to different locations on the same surface of a thin steel strip (2) at the same or different timings.

TECHNICAL FIELD

The present invention relates to an adhesive application device, an apparatus for producing a laminated steel core having the adhesive application device, and a method for producing a laminated steel core.

The present invention relates to an adhesive application device, an apparatus for producing a laminated steel core having the adhesive application device, and a method for producing a laminated steel core. In particular, the present invention relates to an adhesive application device for applying an adhesive to a thin steel strip, an apparatus for producing a laminated steel core by stacking steel core sheets having a predetermined shape that are punched out from a thin steel strip to which an adhesive has been applied using the adhesive application device, and a method for producing a laminated steel core.

BACKGROUND ART

Laminated steel cores for rotating electric machines are generally manufactured from an electromagnetic steel hoop (thin steel strip) as a starting material by feeding the thin steel strip to a progressive die assembly. In the die assembly, the thin steel strip is subjected to progressive punching operation to create a predetermined shape, such as pilot holes, slots and inner teeth, thereby producing steel core sheets in a sequential manner. Then, a predetermined number of the steel core sheets are stacked on top of one another and bonded together to form a laminated steel core. The steel core sheets are conventionally assembled together by lamination interlocking, in which steel core sheets are provided with projections and recesses for interlocking, and stacked on top of one another and interlocked together under pressure. Alternatively, the steel core sheets are assembled together by lamination welding, in which steel core sheets are stacked on top of one another and welded together by laser. However, these lamination techniques suffer from the drawback of deterioration of the magnetic properties at the interlocking locations or the welded locations. Under these circumstances, lamination bonding has been widely proposed as an alternative technique, in which an adhesive is applied to the surface of a thin steel strip in a die assembly, and steel core sheets are punched out from the thin steel strip and are stacked on top of one another and bonded together to form a laminated steel core.

For example, Patent literature 1 discloses an apparatus for producing a laminated steel core. In the production process of a laminated steel core formed from a plurality of steel core sheets31as illustrated inFIG.10attached hereto, a hoop W is subjected to preliminary punching process to sequentially create (1) pilot holes P, (2) a prefabricated hole d1 for forming the central hole of a steel core sheet31, (3) slots S, (4) the central hole d of the steel core sheet31, and (5) internal teeth m, thereby creating the basic shape of the steel core sheet31except for the external shape. The hoop is then successively subjected to (6) adhesive application step, (7) blanking step, (8) rotary stacking step, and (9) heating step. When the laminated steel core32has different cross sections depending on the position of the slice as shown inFIG.11, the amount of the adhesive applied to the steel core sheet31should be adjusted to an appropriate amount according to the bonding strength required for the applied area of the laminated steel core32. To this end, the apparatus for producing a laminated steel core is provided with first to third adhesive storage grooves33to35as shown inFIG.12, and supply of the adhesive to the second adhesive storage groove34is intermittently stopped.

Patent literature 2 discloses an apparatus for producing a motor comprising a rotor and a stator. In the production process of the motor using the apparatus, rotor cores are punched out from a rolled electrical steel sheet, stacked on top of one another, and secured together by interlocking to produce the rotor. Stator cores are also punched out from the rolled electrical steel sheet, stacked on top of one another, and secured together by interlocking.

Patent literature 3 discloses an apparatus for producing a laminated steel core. In the production process of a laminated steel core formed from a plurality of steel core sheets using the apparatus as shown inFIG.14, a thin steel strip64is punched to sequentially create (1) pilot holes, (2) a prefabricated hole for forming the central hole of a steel core sheet and small holes for forming grooves on the outer edge of the steel core sheet, (3) slots, (4) the central hole of the steel core sheet, and (5) internal grooves (teeth), thereby creating the basic shape of the steel core sheet except for the external shape. The thin steel strip is then successively subjected to (6) adhesive application step, (7) blanking step, (8) rotary stacking step, and (9) heating step. In the figure, the numeral61denotes an upper die, the numeral62denotes a lower die, and the numeral63denotes the laminated steel core. The apparatus for producing a laminated steel core comprises an adhesive application device65within the lower die62. The adhesive application device65is used to apply an adhesive to the lower surface of the thin steel strip64and has an elevating unit therein.

Citation List

Patent Literature

Patent literature 2: JP 2005-65479 A

Patent literature 3: JP 2009-124828 A

SUMMARY OF INVENTION

Technical Problem

The apparatus for producing a laminated steel core as disclosed in Patent literature 1 suffers from a time lag between when the operator stops or restarts the supply of the adhesive and when the supply of the adhesive is actually stopped or restarted. Due to this, the adhesive may be applied to an area not requiring application of the adhesive, or shortage of the adhesive may occur on an area requiring application of the adhesive. Some amount of the adhesive may be wasted.

In the production process using the apparatus for producing a motor as disclosed in Patent literature 2, when the rotor cores and the stator cores are laminated not by interlocking but by adhesion bonding, the production process is carried out as shown inFIG.13. In particular, as shown in the figure, a blank42is punched out from a thin steel strip41, and the thin steel strip41is transferred in the direction indicated by the arrow43at a feedpitch P. An adhesive for rotor cores is then applied to the lower surface of the thin steel strip41using a dispense unit44configured to dispense the adhesive for rotor cores. A rotor core46is blanked out from the thin steel strip41, and stacked on another rotor core46in a rotor core blanking and laminating step45. Openings47of a stator core are then punched in the thin steel strip41, and an adhesive for stator cores is applied to the lower surface of the thin steel strip41using a dispense unit48configured to dispense the adhesive for stator cores. A stator core50is blanked out from the thin steel strip41, and stacked on another stator core50in a stator core blanking and laminating step49. By a way of illustration, after rotor cores46are stacked to about half of the thickness of the laminated stator cores50, the rotor block is rotated at any given angle and stacked on another rotor block prepared by stacking rotor cores46to about half of the thickness of the laminated stator cores50. In this process, a cycle with no need of adhesive application to the thin steel strip will occur every time when rotor cores46are stacked to about half of the thickness of the laminated stator cores50. Accordingly, at least two adhesive application devices have to be installed, each dedicated for the rotor cores or stator cores, so that adhesive application to the thin steel strip is stopped at different timings.

The apparatus for producing a laminated steel core as disclosed in Patent literature 3 comprises an adhesive application device within the lower die, and the adhesive application device has an elevating unit therein. Due to this configuration, the die is relatively large, and high maintenance cost of the apparatus may be required.

The present invention relates to an improved device and method to solve the above technical problems in the conventional art. An object of the invention is to provide an adhesive application device configured to apply a necessary and sufficient amount of an adhesive to a thin steel strip without causing the problem of increase in the equipment cost. Another object of the invention is to provide an apparatus for producing a laminated steel core having the adhesive application device. Yet another object of the invention is to provide a method for producing a laminated steel core.

Solution to Problem

A first aspect of the invention of the present application for solving the above problems is directed to an adhesive application device comprising a plurality of adhesive application devices that are integrated into a single process, wherein the plurality of adhesive application devices are configured to independently apply an adhesive to a thin steel strip.

A second aspect of the invention of the present application is directed to the adhesive application device according to the first aspect of the invention, wherein the plurality of adhesive application devices comprise an inner adhesive application device and an outer adhesive application device.

A third aspect of the invention of the present application is directed to the adhesive application device according the first aspect of the invention, wherein the adhesive application device further comprises an elevating and lowering mechanism configured to elevate and lower the plurality of adhesive application devices independently.

A forth aspect of the invention of the present application is directed to the adhesive application device according to the second aspect of the invention, wherein the adhesive application device further comprises an elevating and lowering mechanism configured to elevate and lower the inner and outer adhesive application devices independently.

A fifth aspect of the invention of the present application is directed to the adhesive application device according to any one of the first to fourth aspects of the invention, wherein the tips of the adhesive dispense nozzles of the adhesive application device are inwardly spaced apart from the surface of the thin steel strip abutting the adhesive application device.

A sixth aspect of the invention of the present application is directed to the adhesive application device according to any one of the first to fifth aspects of the invention, wherein the adhesive application device is disposed at a location other than a die.

A seventh aspect of the invention of the present application is directed to the adhesive application device according to the sixth aspect of the invention, wherein the adhesive application device further comprises an elevating and lowering mechanism configured to elevate and lower the thin steel strip.

An eighth aspect of the invention of the present application is directed to the adhesive application device according to any one of the third to seventh aspects of the invention, wherein the adhesive application device further comprises a shock absorber for attenuating the impact of the elevating and lowering movement of the adhesive application device.

A ninth aspect of the invention of the present application is directed to the adhesive application device according to any one of the first to eighth aspects of the invention, wherein the adhesive application device further comprises a sensor for sensing the application of the adhesive to the thin steel strip.

A tenth aspect of the invention of the present application is directed to the adhesive application device according to any one of the first to ninth aspects of the invention, wherein the adhesive application device further comprises a heating mechanism for the adhesive.

An eleventh aspect of the invention of the present application is directed to an apparatus for producing a laminated steel core, the apparatus comprising a plurality of adhesive application devices that are integrated into a single process and are configured to independently apply an adhesive to a thin steel strip, and a plurality of dies that are integrated into a single process and are configured to punch the adhesive-applied thin steel strip into a predetermined shape.

A twelfth aspect of the invention of the present application is directed to the apparatus for producing a laminated steel core according to the eleventh aspect of the invention, wherein steel core sheets punched out from the thin steel strip to which the adhesive has been applied in accordance with the dies used in the single process have different lamination thicknesses.

A thirteenth aspect of the invention of the present application is directed to a method for producing of a laminated steel core, wherein the method is performed using an apparatus comprising a plurality of adhesive application devices that are integrated into a single process and are configured to independently apply an adhesive to a thin steel strip, and a plurality of dies that are configured to punch the adhesive-applied thin steel strip into a predetermined shape, and wherein the method comprisesapplying an adhesive to a thin steel strip using one of the plurality of adhesive application devices,punching the adhesive-applied thin steel strip by the dies to produce steel core sheets having a predetermined shape, andstacking the steel core sheets.

Advantageous Effects of Invention

According to the first, second, third and fourth aspects of the invention, a plurality of adhesive application devices are integrated into a single process, which results in miniaturization of the apparatus. A necessary and sufficient amount of the adhesive is applied to the thin steel strip by switching the plurality of adhesive application devices as needed. According to the fifth aspect of the invention, even when an error occurs in the height of the elevated adhesive application devices, a necessary and sufficient amount of the adhesive is applied to the thin steel strip. According to the sixth aspect of the invention, the dies can be made smaller in size than conventional dies having an adhesive application device therein, and maintenance of the apparatus can easily be performed. An adhesive supply unit can be disposed near the adhesive application devices, and consequently adhesive flow passages may be shorter and the response time to an operator’s request to supply the adhesive or stop the supply of the adhesive may be shortened, thereby reducing the amount of the adhesive wasted. According to the seventh aspect of the invention, a necessary and sufficient amount of the adhesive is applied to the thin steel strip by stopping and/or restarting the application of the adhesive to the thin steel strip by means of any one of the plurality of adhesive application devices that are integrated in a single process. The eighth aspect of the invention makes it easier to perform appropriate maintenance on the apparatus. According to the ninth aspect of the invention, the sensor ensures the proper application of the adhesive to the thin steel strip, and if the adhesive application devices fail to apply a necessary amount of the adhesive to the thin steel strip, the operator can carry out appropriate procedures. According to the tenth aspect of the invention, the fluidity of the adhesive is increased and the adhesive can easily be applied to the thin steel strip. According to the eleventh, twelfth and thirteenth aspects of the invention, even when the application of the adhesive to the thin steel strip by means of the adhesive application devices is stopped and/or restarted in accordance with the dies used in the single process, stable application of the adhesive to the thin steel strip is ensured, and the productivity of the laminated steel core is improved.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below with reference to the attached drawings. Various alterations and modifications are possible within the technical scope of the present invention.

FIG.1is a schematic configuration diagram of an embodiment of an apparatus for producing a laminated steel core comprising the adhesive application device of the present invention and other devices placed in-line before and after the adhesive application device. In the figure, the numeral1denotes a coil of a wound thin steel strip2. The numeral3denotes an inner adhesive application device. The numeral4denotes an outer adhesive application device. The numeral5denotes an elevating and lowering mechanism configured to elevate and lower the inner adhesive application device. The numeral6denotes an elevating and lowering mechanism configured to elevate and lower the outer adhesive application device. The numeral7denotes an upper die, and the numeral8denotes a lower die. The inner and outer adhesive application devices3,4are configured to be independently elevated and lowered by the elevating and lowering mechanisms5,6, respectively. The inner and outer adhesive application devices3,4are located immediately before the upper and lower dies as shown inFIG.1. The thin steel strip2is drawn from the coil1, and an adhesive is applied to the lower surface of the thin steel strip2using the inner and outer adhesive application devices3,4. The thin steel strip2is then punched by the upper and lower dies7,8and optionally subsequent upper and lower dies to create a predetermined shape, and transferred in the direction indicated by the arrow A.

FIG.2is a perspective view of an embodiment of the adhesive application device of the present invention. In the figure, the numeral10denotes an adhesive application zone of the inner adhesive application device3, in which dispense nozzles are annularly arranged. The numeral11denotes an adhesive application zone of the outer adhesive application device4, in which dispense nozzles are annularly arranged. The adhesive application zone10in which the dispense nozzles are annularly arranged is configured to be elevated and lowered together with a central circular area10aand an outer annular area10bof the inner adhesive application device3by one of the elevating and lowering mechanisms (described in detail later). The adhesive application zone11in which the dispense nozzles are annularly arranged is configured to be elevated and lowered by another elevating and lowering mechanism. The numeral12denotes a plurality of laser sensors for sensing the application of the adhesive to the thin steel strip. The numeral13denotes an electromagnetic valve for controlling the elevating and lowering movement of the elevating and lowering mechanisms configured to elevate and lower the inner and outer adhesive application devices. The numeral14denotes cartridge heaters for increasing the temperature of the adhesive. The numeral15denotes a temperature sensor for sensing the temperature of the inner adhesive application device3comprising the adhesive application zone10in which the dispense nozzles are annularly arranged and the central circular area10aand the outer annular area10b. The numeral16denotes a temperature sensor for sensing the temperature of the outer adhesive application device4comprising the adhesive application zone11in which the dispense nozzles are annularly arranged.

FIG.3is a plan view of an embodiment of the adhesive application device of the present invention. The numeral17denotes supply ports for supplying the adhesive to the adhesive application zone10of the inner adhesive application device3, in which the dispense nozzles are annularly arranged. The numeral18denotes supply ports for supplying the adhesive to the adhesive application zone11of the outer adhesive application device4, in which the dispense nozzles are annularly arranged. The supply ports17,18are detachable.

FIG.4is a side view of an embodiment of the adhesive application device of the present invention. The numeral19denotes shock absorbers for attenuating the impact of the elevating and lowering movement of the outer adhesive application device4comprising the adhesive application zone11in which the dispense nozzles are annularly arranged. The numeral20denotes shock absorbers for attenuating the impact of the elevating and lowering movement of the inner adhesive application device3comprising the adhesive application zone10in which the dispense nozzles are annularly arranged and the central circular area10aand the outer annular area10b.

FIG.6is a front view of an embodiment of the adhesive application device of the present invention. The numeral21denotes air cylinders for elevating and lowering the outer adhesive application device4comprising the adhesive application zone11in which the dispense nozzles are annularly arranged. The numeral22denotes an air cylinder for elevating and lowering the inner adhesive application device3comprising the adhesive application zone10in which the dispense nozzles are annularly arranged and the central circular area10aand the outer annular area10b. The numeral23denotes a photomicrosensor for sensing the upper and lower limits of the movement of the air cylinders21. The numeral24denotes a photomicrosensor for sensing the upper and lower limits of the movement of the air cylinder22. The adhesive application device is provided with more than one air cylinder21and more than one air cylinder22.

FIG.8is a plan view of an embodiment of adhesive flow passages in the adhesive application device of the present invention. The width d of the flow passages25in this embodiment is constant along its entire length. The adhesive is supplied through the flow passages25, and dispensed from dispense nozzles26,27on the adhesive application zones10,11in which the dispense nozzles are annularly arranged as shown inFIG.3.FIG.9is a plan view of another embodiment of adhesive flow passages in the adhesive application device of the present invention. The width w of the flow passages28in this embodiment is tapered toward the outlets of the flow passages28. When the length of the flow passages is relatively long, such tapered flow passages are advantageous in that the adhesive can be easily delivered to the outlets of the flow passages. InFIGS.1to3, the adhesive application zones10,11in which the dispense nozzles are annularly arranged (on the top surfaces of the adhesive application devices) are positioned slightly lower than the top surface of the lower die8. Such adhesive application zones10,11positioned to be recessed from the top surface of the lower die8are advantageous in that the adhesive dispensed from the dispense nozzles26,27is not immediately applied to the lower surface of the thin steel strip (indicated by the numeral2inFIG.1), but the adhesive rising on the dispense nozzles26,27is applied to the lower surface of the thin steel strip so that the amount of the adhesive applied is constant.

A method for applying an adhesive to a thin steel strip using the adhesive application device configured as described above will be described below.

The adhesive is not continuously applied to the thin steel strip2, but is rather applied to the thin steel strip2in synchronization with the timing of punching the thin steel strip2into a predetermined shape by lowering the upper die7toward the lower die8in the configuration as shownFIG.1. In particular, when referring toFIG.1, at the timing when punching is not performed, a predetermined distance (about several millimeters) is provided between the thin steel strip2and the components of the apparatus for producing a laminated steel core, including the top surface of the inner adhesive application device3, the top surface of the outer adhesive application device4, the top surfaces of platforms 9a, 9b and the top surface of the lower die8. In the configuration shown in the figure, at the timing when the upper die7is lowered toward the lower die8to punch the thin steel strip2into a predetermined shape, the thin steel strip2is pressed against the lower die8. Since the inner and outer adhesive application devices3,4are configured to be independently elevated and lowered, the inner and outer adhesive application devices3,4can independently be elevated to a height at which the top surfaces of the inner and outer adhesive application devices are positioned slightly lower than the lower surface of the thin steel strip2. The adhesive stored in a tank (not shown) is constantly supplied to the inner and outer adhesive application devices3,4at a predetermined pressure, and is applied to the lower surface of the thin steel strip2.

After the adhesive is applied to the lower surface of the thin steel strip2as described above, the thin steel strip2is punched by the upper and lower dies7,8and optionally subsequent upper and lower dies into a predetermined shape to produce steel core sheets. The steel core sheets having a predetermined shape are stacked on top of one another within the lower die8or an optionally subsequent lower die. After the stacked core sheets reach a predetermined number, the stacked core sheets are dispensed from the lower die8or an optionally subsequent lower die. The stacked core sheets are subjected to a given post-treatment such as heating, and used for the assembly of electric parts . For example, when referring toFIG.1, at the timing of punching the thin steel strip2into a predetermined shape by lowering the upper die7toward the lower die8, only the inner adhesive application device3is elevated toward the lower surface of the thin steel strip2to apply the adhesive to the lower surface of the thin steel strip2. The adhesive-applied thin steel strip2is punched by the upper and lower dies7,8into a predetermined shape to produce a steel core sheet. The steel core sheet is stacked on another steel core sheet within the lower die8. Then, at the timing of punching the thin steel strip2into a predetermined shape by lowering an optionally subsequent upper die toward an optionally subsequent lower die, only the outer adhesive application device4is elevated toward the lower surface of the thin steel strip2to apply the adhesive to the lower surface of the thin steel strip2. The adhesive-applied thin steel strip2is punched by the subsequent upper and lower dies into a predetermined shape to produce a steel core sheet. The steel core sheet is stacked on another steel core sheet within the lower die.

The adhesive is supplied from a tank (not shown) at a predetermined pressure toward the inner and outer adhesive application devices3,4as described above, and reaches the supply ports17,18as shown inFIG.3. The adhesive is then dispensed from the dispense nozzles26of the adhesive application zone10in which the dispense nozzles are annularly arranged and from the dispense nozzles27of the adhesive application zone11in which the dispense nozzles are annularly arranged, and is applied to the lower surface of the thin steel strip. The adhesive application zone10in which the dispense nozzles are annularly arranged is configured to be elevated and lowered together with the central circular area10aand the outer annular area10bby one of the elevating and lowering mechanisms (described in detail later). The adhesive application zone11in which the dispense nozzles are annularly arranged is configured to be elevated and lowered by another elevating and lowering mechanism. In this manner, the inner and outer adhesive application devices3,4are integrated into a single apparatus, and the inner and outer adhesive application devices may be configured to be independently elevated and lowered. Due to this configuration, miniaturization of the adhesive application devices, the dies and the apparatus for producing a laminated steel core can be achieved and the configuration of the apparatus can be simplified, which may lead to a significant reduction in the equipment cost, as compared with the conventional apparatus for producing a laminated steel core as shown inFIG.13.

Specifically, in the inner adhesive application device3, the adhesive application zone10in which the dispense nozzles are annularly arranged is configured to be elevated and lowered together with the central circular area10aand the outer annular area10bby the air cylinder22as shown inFIG.6. In the outer adhesive application device4, the adhesive application zone11in which the dispense nozzles are annularly arranged is configured to be elevated and lowered by the air cylinders21as shown inFIG.6.

When a laminated core as shown inFIG.11is intended to be produced, a necessary and sufficient amount of the adhesive is applied to the lower surface of the thin steel strip by switching the plurality of adhesive application devices as needed. The present invention can be used to produce not only a concentric laminated core but also a laminated core that is partitioned in the circumferential direction or other types of laminated cores.

The movement of the air cylinders21,22is controlled by the electromagnetic valve13as shown inFIG.2. The upper and lower limits of the elevating and lowering movement of the air cylinders are sensed by the photomicrosensors23,24as shown inFIG.6. The shock absorbers19,20as shown inFIG.4attenuate the impact of the elevating and lowering movement on the components of the apparatus and shorten a waiting time until the vibration by the impact stops.

The adhesive application device of the invention comprises the plurality of laser sensors12for sensing the application of the adhesive to the thin steel strip as shown inFIG.2. When the laser sensors12detect that the adhesive application device has failed to apply the adhesive to the thin steel strip, this information detected by the laser sensors12is sent as a feedback to the tank (not shown) storing the adhesive, and supply of the adhesive to the inner and outer adhesive application devices3,4is stopped to allow the operator to carry out necessary procedures such as inspection and repair.

Referring back toFIG.2, the cartridge heaters14for increasing the temperature of the adhesive are coupled to a power supply (not shown). By heating the adhesive with the cartridge heaters14, the fluidity of the adhesive can be increased and the adhesive can be stably dispensed from the dispense nozzles26,27as shown inFIG.3. The temperature sensors15,16can sense an abnormal rise in the temperature in the apparatuses, and based on the detected temperature, the number of the cartridge heaters14in operation can be adjusted as needed. Since the inner and outer adhesive application devices3,4are located outside the upper and lower dies7,8, the temperature rise by the cartridge heaters14has no influence on the dies, and simultaneously, temperature changes in the dies have no influence on the fluidity of the adhesive.

INDUSTRIAL APPLICABILITY

The adhesive application device of the present invention can be used to apply an adhesive to a thin steel strip for the production of laminated steel cores for stepper motors or motor cores.

REFERENCE SIGNS LIST

1Coil2Thin steel strip3Inner adhesive application device4Outer adhesive application device5Elevating and lowering mechanism for inner adhesive application device6Elevating and lowering mechanism for outer adhesive application device7Upper die8Lower die9a,9bPlatforms10Adhesive application zone in which dispense nozzles are annularly arranged10aCentral circular area10bOuter annular area11Adhesive application zone in which dispense nozzles are annularly arranged12Laser sensors13Electromagnetic valve14Cartridge heaters15,16Temperature sensors17,18Adhesive supply ports19,20Shock absorbers21,22Air cylinders23,24Photomicrosensors25,28Flow passages26,27Dispense nozzles