JP2006315066A - Pressing device, press-fitting method used for the pressing device, and press-fitting program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressing device where a bottom dead point is correctly detected, thus the quality of a product can be maintained. <P>SOLUTION: The pressing device is composed of: a pressurizing mechanism part having an elevating rod: a load detecting means connected to the elevating rod; a position detecting means for detecting the position of the elevating rod; and a controlling means electrically connected to the pressurizing mechanism part, the load detecting means and the position detecting means. The controlling means is provided with: a variation calculating part of calculating the detected variation in loads and the detected variation in positions per unit time; a coefficient calculating part of calculating the variation coefficient as a ratio between the detected variation in loads and the detected variation in positions per unit time; a comparison calculating part of comparing the variation coefficient and prescribed threshold value; and a judging part, in the case the variation coefficient exceeds the prescribed threshold value as a result of the comparison, judging that the bottom dead part of the elevating rod is detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a press apparatus, a press-in method used in the press apparatus, and a press-in program. More specifically, the present invention relates to a press apparatus capable of monitoring the amount of change in load and position in the press-fitting region and accurately detecting bottom dead center, a press-in method used in the press apparatus, and a press-in program.

  Conventionally, when a press-fitting material such as a shaft is press-fitted into a press-fitted material such as a bearing hole, even if these have dimensional accuracy within a tolerance range, there is some variation in press-fitting depending on the combination. When press-fitting with a constant press-fitting load, the product quality after assembly such as insufficient press-fitting that the bearing cannot be press-fitted into a predetermined position of the shaft or excessive press-fitting occurs. For this reason, assembly is performed while confirming the press-fitted state. For example, there is a press-fitting device that performs press-fitting while confirming a press-fitting amount and a press-fitting load (see Patent Document 1).

Japanese Patent Application Laid-Open No. 5-177560

  However, the press-fitting amount and the press-fitting load are detected amounts at a certain point in time, not a change amount per unit time. Therefore, the detected value must be set at several points or determined based on continuously measured values, and setting / judgement becomes complicated, so that it is difficult to maintain product quality.

  In view of the above, in the case of press-fitting, the present invention considers that the press-fitting load at the bottom dead center is important, and the press device capable of maintaining product quality by accurately detecting the bottom dead center and the press An object is to provide a press-fitting method and a press-fitting program used for the apparatus.

  The press device according to the present invention includes a pressurizing mechanism having an elevating rod, load detecting means coupled to the elevating rod, position detecting means for detecting the position of the elevating rod, the pressurizing mechanism, and load detection. And a control device electrically connected to the position detection means, wherein the control means calculates a detected change amount of the load and a detected change amount of the position in unit time; A coefficient calculation unit that calculates a variation coefficient that is a ratio of the detected change amount of the load and the detected change amount of the position in the unit time, a comparison calculation unit that compares the variation coefficient with a predetermined threshold value, When the coefficient of variation exceeds a predetermined threshold value as a result of comparison, a judgment unit is provided that judges that the bottom dead center of the lifting rod has been detected.

  Further, the press-fitting method of the present invention includes a pressurizing mechanism having an elevating rod, load detecting means connected to the elevating rod, position detecting means for detecting the position of the elevating rod, the pressurizing mechanism, A press-fitting method used in a press device such as a load detecting means and a control means electrically connected to a position detecting means, the step of calculating a detected change amount of a load and a detected change amount of a position per unit time, and the unit A step of calculating a coefficient of variation that is a ratio of a detected change amount of load to a detected amount of change of position in time, a step of comparing the variation factor with a predetermined threshold value, and the variation coefficient as a result of the comparison And a step of determining that the bottom dead center of the elevating rod has been detected when the value exceeds a predetermined threshold value.

  Further, the press-fitting program of the present invention includes a computer for detecting the bottom dead center of the lifting rod in the press device, a change amount calculation unit for calculating the detected change amount of the load and the detected change amount of the position in unit time, the unit time A coefficient calculation unit that calculates a coefficient of variation that is a ratio of the detected change amount of the load and the detected change amount of the position, a comparison calculation unit that compares the variation coefficient with a predetermined threshold value, and as a result of the comparison, the variation When the coefficient exceeds a predetermined threshold value, it functions as a determination unit that determines that the bottom dead center of the lifting rod has been detected.

  According to the present invention, the ratio (variation coefficient) of the detected change amount of the load and the position per unit time is constantly monitored, and when the fluctuation coefficient exceeds a predetermined threshold value, it is determined that the bottom dead center has been detected. By doing so, the bottom dead center can be accurately detected.

  Moreover, since press-fitting is completed with the press-fitting load at the detected bottom dead center, product quality can be maintained.

  Hereinafter, a press apparatus of the present invention, a press-in method used in the press apparatus, and a press-in program will be described with reference to the accompanying drawings.

  As shown in FIG. 1, a press apparatus according to an embodiment of the present invention includes a pressurizing mechanism A, a load detecting means B and a position detecting means C disposed above a base 1, and the pressurizing mechanism. It is comprised from the control part D which is a computer electrically connected to the mechanism part A, the load detection means B, and the position detection means C. As the control means D, for example, an I / O interface necessary for signal exchange with an external device, a CPU functioning as the center of arithmetic processing, a ROM storing a control operation program of the CPU, and the CPU It is possible to use a configuration in which data or the like is temporarily written when the control operation is performed, or a RAM from which the written data is read.

  A guide rod 3 is erected on the four corners of the table 2 placed on the base 1, and an upper frame 4 is connected to the upper end of the guide rod 3. A movable frame 6 having a holder 5 is disposed between the upper frame 4 and the table 2. The guide rod 3 passes through the holder 5 so as to be slidable in the vertical direction.

  In addition, an electric cylinder 8 as a component of the pressurizing mechanism A to which an encoder 7 as the position detecting means C is attached is connected to the upper center of the upper frame 4. Includes a connecting mechanism that converts rotation into linear motion so that the lifting rod 10 as another component of the pressurizing mechanism section A is raised and lowered by the rotation of the motor 9. The position of the lifting rod 10 is detected by the encoder 7. Or the linear gauge 7a can be provided in the vicinity of the workpiece | work W1, and the position of the raising / lowering rod 10 can also be detected.

  A load cell 11 as load detecting means B is connected to the tip of the lifting rod 10 via the movable frame 6, and a pressing member (not shown) holding the workpiece W 1 is attached to the tip of the load cell 11. Are connected). A work W2 is placed on the table 2 below the work W1.

  The control means D includes a change amount calculation unit for calculating a detected change amount of the load and a detected change amount of the position in unit time, and a variation that is a ratio of the detected change amount of the load and the detected change amount of the position in the unit time. A coefficient calculation unit that calculates a coefficient, a comparison calculation unit that compares the coefficient of variation with a predetermined threshold value, and if the coefficient of variation exceeds a predetermined threshold value as a result of the comparison, A calculation unit 21 including a determination unit that determines that a dead point has been detected is provided. Further, the control means D is used for setting a pressurizing condition as an external input to the command unit 22 for transmitting an operation signal of the pressurizing speed of the lifting rod to the motor 9 of the pressurizing mechanism unit and the arithmetic unit 21. A condition setting unit 23 is also provided. The control means D feedback controls the rotation of the pressurizing motor 9 based on the measurement data input from the encoder 7.

  In the press-fitting program in the present embodiment, the control means D functions as a change amount calculation unit, a coefficient calculation unit, a comparison calculation unit, and a determination unit, and can also function as a command unit.

Next, a press-fitting method for a press apparatus according to an embodiment of the present invention will be described with reference to FIG.
(1) First, the set pressure condition is input (step S1). This pressurizing condition is a decelerating condition at the time of press-fitting (a condition for decelerating the speed of the rod when the load at the time of press-fitting increases), etc. This is to suppress overshoeing of the load due to press-fitting at high speed.
(2) Next, a threshold value is set for the ratio between the amount of change in load of the lifting rod and the amount of change in position in unit time for detecting bottom dead center, that is, the ratio of detection change (coefficient of variation) ( Step S2). This threshold value can be determined in advance by experiments or the like. The unit time can be set to 0.1 sec, 0.05 sec, or the like.
(3) Next, the lifting rod is lowered at a preset operation speed (step S3). This state is the operation until press-fitting.
(4) Next, the pressurization speed is determined while measuring the load in the press-fitting region (step S4). That is, the pressurization speed is determined by the calculation unit from the pressurization condition and the load detected by the load cell. After this pressurization speed is inputted to the command section, the command section gives a signal for lowering the lifting rod at this pressurization speed to the motor.
(5) The coefficient of variation M of the press-fitted region is calculated together with step S4 (step S5).
(6) The variation coefficient M is compared with a threshold value Hth of the variation coefficient (step S6). For example, although the load increases when entering the press-fitting region, since the position change is large at this point, the variation coefficient does not increase, and this point is not detected as the bottom dead center. On the other hand, when the lifting rod descends further and reaches the bottom dead center, the amount of change in position per unit time becomes extremely small, and the load changes abruptly at this point (because the lifting rod is prevented from descending by the table). . For example, the amount of change in the load in the press-fitting region changes as shown in FIG. 3, and the coefficient of variation is found to change abruptly at the bottom dead center among the changes in the press-in region as shown in FIG. . Accordingly, when the variation coefficient M exceeds a predetermined threshold value Hth, it can be determined that the bottom dead center has been detected.
(7) Next, it is determined in step S6 that a bottom dead center has been detected (step S7).
(8) Next, after checking the load at the bottom dead center, the press-fitting is completed (step S8).

  When the press-fitting is completed, the holding of the work W1 is released, and then the motor is reversely rotated to raise the lifting rod. After that, the finished products (work W1 and work W2) are taken out from the table 2.

  In this embodiment, the bottom dead center is accurately detected by constantly monitoring the coefficient of variation of the press-fitted region and determining that the bottom dead center has been detected when the coefficient of variation exceeds a predetermined threshold. can do. Thereby, for example, since it is not necessary to give an extra load after the bottom dead center, damage to the workpiece can be reduced. Therefore, the product quality after press-fitting can be maintained.

It is the schematic of the press apparatus concerning one embodiment of this invention. It is a flowchart concerning one embodiment of the present invention. It is a figure which shows an example of the variation | change_quantity of a load. It is a figure which shows an example of a variation coefficient.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 2 Table 3 Guide rod 4 Upper frame 5 Holder 6 Movable frame 7 Encoder 7a Linear gauge 8 Electric cylinder 9 Motor 10 Lifting rod 11 Load cell 21 Calculation part 22 Command part 23 Condition setting part

Claims (5)

A pressurizing mechanism having a lifting rod, a load detecting means connected to the lifting rod, a position detecting means for detecting the position of the lifting rod, and the pressurizing mechanism, the load detecting means and the position detecting means A press device comprising a control means connected to each other, wherein the control means calculates a detected change in load and a detected change in position in unit time, and a load calculation unit in the unit time. A coefficient calculation unit that calculates a variation coefficient that is a ratio of the detected change amount and the detected change amount of the position; a comparison calculation unit that compares the variation coefficient with a predetermined threshold; and as a result of the comparison, the variation coefficient A press unit comprising: a determination unit that determines that the bottom dead center of the elevating rod is detected when the value exceeds a predetermined threshold value. The press apparatus according to claim 1, further comprising a command unit that transmits an operation signal of a pressing speed of the lifting rod to the pressing mechanism unit. A pressurizing mechanism having a lifting rod, a load detecting means connected to the lifting rod, a position detecting means for detecting the position of the lifting rod, and the pressurizing mechanism, the load detecting means and the position detecting means A press-fitting method used for a press device, which is a control means to be connected electrically, the step of calculating the detected change amount of the load and the detected change amount of the position per unit time, and the detected change amount and the position of the load per unit time Calculating a coefficient of variation that is a ratio to the detected change amount, comparing the coefficient of variation with a predetermined threshold value, and as a result of the comparison, the coefficient of variation exceeds a predetermined threshold value And a press-in method used for a press apparatus including a step of determining that the bottom dead center of the elevating rod has been detected. 4. The press-fitting method according to claim 3, further comprising a step of transmitting an operation signal of a pressurizing speed of the lifting rod to the pressurizing mechanism. In order to detect the bottom dead center of the lifting rod in the press device, a computer, a change amount calculation unit for calculating a detected change amount of the load and a detected change amount of the position in unit time, and a detected change amount and position of the load in the unit time A coefficient calculation unit that calculates a variation coefficient that is a ratio to the detected change amount, a comparison calculation unit that compares the variation coefficient with a predetermined threshold value, and as a result of the comparison, the variation coefficient has a predetermined threshold value. In this case, a press-fitting program for functioning as a determination unit that determines that the bottom dead center of the lifting rod is detected.