KR20040101847A - electric press machine having load cell installed in main body - Google Patents

Abstract

PURPOSE: An electric press machine having a load cell within is provided to prevent the load cell from being damaged and deformed by non-axial load, and perform precise load control. CONSTITUTION: A servo motor(40) is mounted to the bottom of one side of a base plate(80), and has an output shaft(41) on which a driving timing pulley(45) is installed. A load cell(20) is mounted to the bottom of the other side of the base plate. A pipe-shaped press body(10) is fixed to the bottom of the load cell to conform to the load cell in the center line. Upper and lower thrust bearings(5) are inserted into a bearing housing, and adhere closely to the top and bottom of the load cell. A ball screw bolt(30) has a lower screw, and an upper support unit. The inner ring of the lower thrust bearing adheres closely to a support end between the lower screw and the support unit. A driven timing pulley(25) adheres closely to the inner ring of the upper thrust bearing. A ball screw nut(35) is engaged with the screw of the ball screw bolt. A pressing rod(50) is coupled to the ball screw nut, and moves up and down simultaneously with the ball screw nut.

Description

Electric press machine having load cell installed in main body}

The present invention relates to an electric press apparatus using a servo motor, and more particularly, it is possible to miniaturize by embedding the load cell in the main body, to prevent damage of the load cell by external force, and to provide the workpiece with the exact pressing force required during pressurization. It relates to a load cell built-in electric press device.

The press apparatus may be selectively used in various kinds of press apparatuses according to the object to be worked or the type of processing used, and may be classified into a mechanical press apparatus and a hydraulic press apparatus according to the driving method thereof.

Mechanical presses use mechanisms such as cranks, cams, screws, racks, and links, and small presses with power transmission mechanisms such as screws and links are mainly used.

The hydraulic press device uses a hydraulic pump, a hydraulic cylinder, hydraulic piping connecting them, and various types of control valves. The hydraulic press device is advantageous for generating a large pressing force, so that a medium or large press device requires a large force. Mainly used.

In general, a hydraulic press has been used for a job requiring a large force, such as precisely press-fitting a mechanical part such as a bearing, a pin, a shaft, an oil seal, or performing a precision caulking operation.

However, as is commonly known, the hydraulic press device is simple in structure, can easily control the magnitude, speed, direction, etc. of the force generated, can be continuously controlled and remotely operated, and the branching of piping and hydraulic oil can be freely made. Although there are advantages, in order to realize precise position control and precise pressure control, expensive controllers and sensors such as solenoid valves are required, and in addition to undesirable problems in terms of maintaining a pleasant environment such as leakage of oil or noise, The mechanical efficiency changes with the temperature change of the working oil.

In order to overcome the limitations of the hydraulic press device, which is not easy to precise position control and pressure control as described above, more precise indentation work is required in the workplace, shorter working time is required, and consumers have a variety of preferences. As the production method is changed from the mass production method of small items to the small quantity production method of various types, the flexibility to perform various kinds of similar processes is required, and to meet the demand for improving the environment of the workplace, Electric press apparatus using servo motor and ball screw has been developed and used.

As an example of the electric press apparatus according to the prior art, it will be described with reference to the electric press apparatus, as shown in Republic of Korea Utility Model Registration No. 1991-20971.

The electric press device transmits the pressing force to the workpiece through the pressure rod, and uses a ball screw composed of a ball screw bolt, a ball screw nut, and a plurality of balls as a pressure rod reciprocating transfer means. In addition, the servo motor capable of forward and reverse rotation provides a rotational driving force to the ball screw to enable the up and down linear reciprocation of the pressure rod through the transfer means.

In more detail, a ball screw and a pressurized rod, which is also a hollow pipe, are installed inside the press main body provided in the hollow pipe type, and the pressurized rod is coupled to the lower surface side of the ball screw nut to reverse the forward and reverse rotation of the ball screw bolt. As the ball screw nut is raised or lowered, the ball screw nut is raised or lowered together with the ball screw nut. At this time, the ball screw nut is constrained to the guide shaft to block the rotation of itself to perform only the vertical reciprocating movement with the pressure rod. A driven timing pulley is mounted on an upper portion of the ball screw bolt, and the driven timing pulley is configured to interlock with a driven timing pulley mounted on an output shaft of the servomotor through a timing belt. Therefore, by transmitting the rotational driving force of the servo motor capable of precise control to the ball screw bolt, it is possible to vertically reciprocate the vertical movement of the pressure rod through the ball screw nut. In addition, the work tool required for the work is mounted at the end of the pressure rod is to apply a pressing force to the workpiece through the tool when the pressure rod descends.

On the other hand, as the electric press device of the advanced form, as shown in Figure 5, by mounting the load cell (20 ') at the end of the pressure rod (50') has been developed an electric press device capable of more precise pressure control. That is, the fixed end of the load cell 20 'is coupled to the end of the pressure rod 50', and a work tool such as a tool for inserting parts is attached to the measurement end of the load cell 20 ', thereby providing a servo motor ( The rotational force of 40 ') measures the pressing force acting in the axial direction through the ball screw inside the press main body 10', that is, the load.

However, when the load cell 20 'is mounted in the form of being exposed to the outside as described above, wires such as the load cell power source and the signal line connected to the load cell 20' are also exposed to the outside, so that the pressure rod 50 ' As the load cell 20 'is reciprocated up and down in the coupled state, wires must also be stretched and contracted, and thus there is a problem of being a potential danger that may impair the safety of the work. In addition, when a load other than the axial direction acts on the measuring end of the load cell 20 ', the load cell 20' is easily damaged and cannot be used, or the inherent characteristics are changed, thereby reducing the accuracy of the measured value. As the load cell 20 'is externally mounted and exposed to loads in various directions, the load cell 20' may be damaged and the measured value is inaccurate. There was a problem that the precise load control of the electric press apparatus based on the impossible becomes impossible.

In order to solve the problems of the prior art as described above,

An object of the present invention is to mount and fix the load cell inside the main body, thereby preventing work safety from being deteriorated due to external exposure of the load cell power source and signal line, and blocking the load from the axial load from the load cell. It is to provide an electric press device capable of more precise load control by protecting the load cell from deformation or damage.

1 is a longitudinal sectional view showing an electric press apparatus according to an embodiment of the present invention;

2 is an enlarged cross-sectional view of portion A of FIG. 1;

3 is an exploded perspective view showing an electric press apparatus according to an embodiment of the present invention,

Figure 4 is a perspective view of the electric press device according to an embodiment of the present invention,

5 is a front view showing an example of the electric press apparatus according to the prior art.

* Description of the symbols for the main parts of the drawings *

3, 7: bearing housing 5, 9: thrust bearing

10: press main body 11: key guide rail

13, 33, 37: oilless bearing 15: timing belt

20: load cell 23: load cell measurement stage

25: driven timing pulley 29, 31: ball bearing

30: Ball screw bolt 35: Ball screw nut

40: servomotor 45: driving timing pulley

50: pressure rod 51: guide key

53, 57: overrun sensor 55: home proximity sensor

60: anti-bending bracket 80: base plate

85: motor position control plate 90: cover

The present invention for realizing this,

A servo motor mounted on a bottom surface of one side of the base plate such that an output shaft on which the coarse timing pulley is installed protrudes above the base plate;

A load cell in which an upper fixing part is mounted on the other bottom surface of the base plate;

A hollow pipe-type press body having an upper end fixed to the center of the lower fixing part of the load cell;

Each outer ring portion in a fixed state is inserted into the bearing housing, the upper and the lower thrust bearing is fixed to each bearing housing portion is in close contact with the upper and lower measurement terminal of the load cell;

The lower end of the thrust bearing is provided with a support end due to the diameter difference, and the inner ring part of the lower thrust bearing is in close contact with the support end, and a driven timing pulley is provided on the upper part of the support part that protrudes above the base plate. A ball screw bolt installed in close contact with the inner ring of the bearing;

A ball screw nut engaged with the threaded portion of the ball screw bolt to reciprocate up and down; And

It is coupled to the lower portion of the ball screw nut, the pressure rod for reciprocating up and down with the ball screw nut in a state in which the work tool is coupled to the lower end; provides a load cell embedded electric press device comprising a.

The driven timing pulley includes a hub protruding upward, and a bearing is mounted to closely contact an inner ring portion on the outer circumferential surface of the hub. It is characterized in that it further comprises a bending preventing bracket for preventing the bending of the ball screw bolt by the tension of the timing belt provided with a coupling hole.

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

In the electric press apparatus according to the preferred embodiment of the present invention, as shown in Figures 1 to 4, the load cell 20 so that the center and the center of the press main body inside the upper end of the press main body 10 provided in a hollow pipe type This is installed. The load cell 20 has a control unit that protrudes radially from its outer circumferential surface, and when the load cell is assembled, the control unit is assembled to be exposed to the outside through a cutout formed at one side of the upper end of the press body 10, and the signal line and the power line at the control unit. The wiring of the back is drawn out so that it can be connected to a press control device (not shown).

The inner diameter of a predetermined height at the upper end of the press body 10 is formed in an expanded form according to the diameter of the load cell 20, the lower edge of the lower side of the load cell 20 is in close contact with the engaging jaw formed by the diameter difference Is fixed as possible.

The upper and lower thrust bearings 9 and 5 are respectively fixed to the upper and lower measuring stages 23 of the load cell 20. The thrust bearings 9 and 5 have respective outer ring portions bearing housings 7 and 3, respectively. The bearing housings 7 and 3 are respectively fixed to the upper and lower measurement stages 23 of the load cell 20 while being inserted into and fixed to the load cell 20.

As described above, the ball is arranged to sequentially pass through the center hole of the load cell 20 and the upper and lower thrust bearings 9 and 5 in a state where the upper and lower thrust bearings 9 and 5 are mounted to the load cell 20. The screw bolt 30 is installed.

The ball screw bolt 30 is engaged with and interlocked with the ball screw nut 35 as in the known ball screw. The ball screw bolt 30 is divided into a lower thread part 38 and an upper support part 39, and a diameter at the boundary between the thread part and the support part. The support end by the difference is formed. The ball screw bolt 30 is coupled to the inner ring portion of the lower thrust bearing 5 coupled to the load cell 20 through the bearing housing 3 in close contact with the support end. That is, the lower thrust bearing 5, the bearing housing 3, the load cell 20, the bearing housing 7, and the upper thrust bearing 9 which are in close contact with the support end are sequentially formed on the support 39 of the ball screw bolt 30. The inner circumferential surface of the load cell 20 and each of the bearing housings 3 and 7 is not in contact with the outer circumferential surface of the support 39 of the ball screw bolt 30, and the upper and lower thrust bearings 9 (5) Each inner ring portion is coupled in a state of maintaining contact with the outer circumferential surface of the support portion 39.

The upper edge portion of the load cell 20 in which the lower edge portion is in close contact with the latching jaw portion of the press main body 10 is screwed in close contact with the base plate 80. One side of the base plate 80 is formed with a through hole to allow the ball screw bolt 30 to protrude upward, and is fixed so that the upper surface side edge portion of the load cell 20 is in close contact with the lower peripheral portion of the through hole. . That is, the load cell 20 is fixed in close contact with the locking jaw of the upper inner peripheral surface of the press body, the base plate 80 is fixed to the upper edge portion of the load cell 20. At this time, the upper thrust bearing 9 inserted into the bearing housing 7 is positioned in the through hole, and the support 39 of the ball screw bolt 30 protrudes upward from the base plate 80. Will be located.

The driven timing pulley 25 coupled by the key 32 is mounted on the upper part of the support 39 of the ball screw bolt 30 protruding upward from the base plate 80 so as to be in close contact with the inner ring of the upper thrust bearing 9. The timing belt 15 cooperates with the coarse timing pulley 45 described later. In addition, the driven timing pulley 25 is firmly fixed by fastening the lock washer 26 and the lock nut 27 to the screw formed at the top of the ball screw bolt 30 support 39.

On the other hand, the bending prevention bracket 60 is fixed to the base plate 80 so as to support the upper end of the ball screw bolt 30 support 39. The bending prevention bracket 60 is formed to cover the driven timing pulley 25, and has a coupling hole. Then, the driven timing pulley 25 is provided with a hub protruding upward, the ball bearing 29 is mounted to the inner ring portion in close contact with the hub outer peripheral surface, the driven timing pulley 25 in the coupling hole of the bending prevention bracket 60 The outer ring portion of the ball bearing 29 mounted on the hub of the ball is coupled to support the upper end of the ball screw bolt 30 in a freely rotatable state, thereby bending the ball screw bolt 30 due to the tension of the timing belt 15. It is to prevent.

Then, the servo motor 40 is mounted by the fixing bolt 84 through the long hole 82 formed through the bottom of the other side of the base plate 80, the main timing on the output shaft 41 of the servo motor 40 The pulley 45 is installed. Through-holes are also formed in the portion of the base plate 80 that is coupled to the servomotor 40 so that the output shaft 41 of the servomotor 40 can protrude upward. The motor position control plate mounting portion 81 inwardly inward is formed.

The motor positioning plate 85 is installed in the motor positioning plate mounting portion 81, and the fixing bolt 84 is fastened to the screw hole 86 of the motor positioning plate 85 so that the servo motor is fastened. The motor position adjusting plate 85 has an adjustment hole that is slightly larger than the lower diameter of the coarse timing pulley 45 provided in the output shaft 41 of the servomotor 40. Here, the motor position control plate 85 is moved forward or backward toward the ball screw bolt 30 by adjusting the tension adjusting bolt 83 coupled through one side of the base plate 80, the servo motor in this process The position of the 40 is adjusted, so that the tension of the timing belt 15 is adjusted as the interaxial distance between the driven timing pulley 45 and the driven timing pulley 25 is adjusted.

In addition, the upper portion of the base plate 80 is covered with a cover 90 to prevent internal components from being exposed to the outside and contaminated by dust or the like and release of internal mechanical noise.

On the other hand, the ball screw nut 35 is engaged with the threaded portion 38 of the ball screw bolt 30 to be raised or lowered upon rotation of the ball screw bolt 30, the ball screw nut 35 is the press body 10 The oilless bearing 37 is coupled to its outer circumferential surface so as to be located between the inner circumferential surface of the circumferential surface) so as to reciprocate up and down in a minimized friction state.

A hollow shaft pressurizing rod 50 is coupled to the lower portion of the ball screw nut 35, and the pressing rod 50 also reciprocates up and down together during the up and down reciprocation of the ball screw nut 35 so that the lower portion of the ball screw nut 35 10) will be haunted through the lower opening. In addition, the lower end of the pressure rod 50 is equipped with a work tool for directly transmitting the pressing force in contact with the workpiece.

A guide key 51 having a predetermined length, thickness, and width is coupled to an outer circumferential surface of the upper one side of the pressure rod 50, and is pressed in an axial direction to an inner circumferential surface of the press body 10 corresponding to the installation position of the guide key 51. An intaglio key guide rail 11 is formed to extend to the lower end of the main body 10, and the guide key 51 is constrained to the key guide rail 11 so that the ball screw nut during the vertical reciprocation of the pressure rod 50 ( 35 and the pressure rod 50 is prevented from rotating.

In addition, three through holes communicating with the outside are formed on the key guide rails 11, and overrun sensors 53 and 57 are installed in the upper and lower holes to prevent excessive rise or fall of the pressure rod 50. In the middle hole located adjacent to the overrun sensor 53 on the upper side, an origin proximity sensor 55 for setting the reference position of the pressure rod 50 is installed, and the sensor detects the upper surface of the guide key 51 to pressurize it. The position of the rod 50 can be detected.

Then, the ball bearing 31 is mounted on the outer peripheral surface of the lower end of the ball screw bolt 30, the oilless bearing 33 is coupled to the outer ring portion of the ball bearing 31, the outer peripheral surface of the oilless bearing 33 is a pressure rod By sliding contact with the inner circumferential surface of the 50, even when the ball screw bolt 30 is rotated and the pressure rod 50 reciprocates up and down, the noise caused by the bending of the ball screw bolt 30 and the friction between them is prevented. And to enable the smooth up and down reciprocating motion of the pressure rod (50). In addition, by having an oilless bearing 13 in close contact with the inner circumferential surface of the lower end of the press body 10 to make sliding contact with the pressure rod 50, the vertical reciprocating motion of the stable pressure rod 50 in the state of the friction is minimized Make it possible.

Hereinafter, the operation of the electric press apparatus according to the present invention as described above will be described.

In the electric press apparatus according to the present invention, when the workpiece reaches a fixed position under the pressure rod 50 by the conveyor belt, the servo motor 40 is rotated forward, the coarse timing pulley 45 is rotated, the timing belt 15 The rotational force is transmitted to the driven timing pulley 25 by) to rotate the ball screw bolt 30. The ball screw nut 35 is lowered together with the pressure rod 50 by the rotation of the ball screw bolt 30, and from the moment when the work tool mounted on the lower end of the pressure rod 50 comes into contact with the workpiece, Pressing force begins to act on the object.

When the pressing force starts to act on the workpiece, the load cell 20 senses the pressing force acting on the workpiece. That is, the pressing force is transmitted in the order of the work tool, the pressure rod 50, the ball screw nut 35, the ball screw bolt 30, the lower thrust bearing 5, the bearing housing 3, the load cell 20, Finally, the pressing force acting on the load cell 20 is sensed. In this process, no load other than the axial load is transmitted to the load cell 20, and therefore, only the axial load is transmitted to the load cell 20, so that there is a possibility that the load cell may be damaged due to exposure to loads other than the axial direction. It can be used to measure the exact pressing force on the workpiece.

When the required pressing force action on the workpiece is completed, the pressure rod 50 is rapidly raised by reverse rotation of the servomotor 40 to prepare for the next workpiece.

The electric press device according to the present invention as described above is capable of precise positioning control and movable range limitation through the proximity sensor 55 and the upper and lower overrun sensors 53 and 57. First, the upper and lower overrun sensors 53 and 57 are limited to the rising limit and the lowering limit of the pressure rod 50, respectively, so that the device itself may be damaged due to excessive rise or fall of the pressure rod 50, or It prevents damage to the workpiece, and detects a reference position for position control by the proximity sensor 55 to calculate the position control data based on this reference position.

For example, when used for the purpose of providing a pressing force to a workpiece that is continuously supplied through a conveyor belt, etc., the pressure rod 50 is rapidly lowered to the top dead center where the operation is started and at the same time the repetitive work is started. When the control signal is applied, the pressure rod 50 rapidly descends to the pressure start point again. Subsequently, the speed of the pressure rod 50 is rapidly reduced to the bottom dead center to prevent a large impact from occurring momentarily on the workpiece, and then the pressure rod 50 is rapidly raised to the top dead center to operate the cycle. You are done. This process is repeated continuously, during the repeated process, the load cell 20 always measures the exact pressing force acting on the workpiece, and transmits data related to the measured value to the press control device for more precise control with precise position control. It is possible to control the pressing force.

The load cell built-in electric press device according to the present invention as described above, the load cell is mounted inside the press main body to prevent damage to the load cell that may be caused by exposure of the load cell to a load other than the axial load, thereby precisely controlling the pressure position and the pressing force At the same time, the wiring of signal cell and power line of load cell is always fixed regardless of the operation, thus eliminating the risk of work safety due to the expansion and contraction of the wire and advantageously miniaturizing the device. .

In addition, since the upper part of the ball screw bolt becomes a cantilever when the load cell is embedded in the upper part of the press main body, and the upper part of the ball screw bolt is exposed to bending when tension is applied by the timing belt, the rotation is not smooth and causes noise. In order to completely solve the problem that the load cell's measuring part is abnormally loaded, it may shorten the life and reduce the accuracy of the measured value. It will have the effect.

While the invention has been shown and described in connection with specific embodiments, it is conventional in the art that various changes, modifications and variations are possible without departing from the spirit and scope of the invention as indicated by the appended claims. Anyone with knowledge of this will easily know.

Claims (2)

A servo motor mounted on a bottom surface of one side of the base plate such that an output shaft on which the coarse timing pulley is installed protrudes above the base plate; A load cell in which an upper fixing part is mounted on the other bottom surface of the base plate; A hollow main body press body having an upper end fixed to a center of the lower fixed part of the load cell; Each outer ring portion in a fixed state is inserted into the bearing housing, the upper and the lower thrust bearing is fixed to each bearing housing portion is in close contact with the upper and lower measurement terminal of the load cell; The lower end of the thrust bearing is provided with a support end due to the diameter difference, and the inner ring part of the lower thrust bearing is in close contact with the support end, and a driven timing pulley is provided on the upper part of the support part that protrudes above the base plate. A ball screw bolt installed in close contact with the inner ring of the bearing; A ball screw nut engaged with the threaded portion of the ball screw bolt to reciprocate up and down; And And a pressure rod coupled to a lower portion of the ball screw nut and configured to reciprocate up and down with the ball screw nut in a state in which a work tool is coupled to a lower end thereof. The method of claim 1, The driven timing pulley has a hub protruding upward, and a bearing is mounted on the outer peripheral surface of the hub so as to be in close contact with the hub, and is formed to cover the driven timing pulley and is fixed to the base plate and coupled to the outer ring part of the bearing. A load cell built-in electric press apparatus further comprising a bending prevention bracket provided with a ball to prevent bending of the ball screw bolt due to the tension of the timing belt.