JPH0755396B2 - Billet for press load test verification and press load test method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load test of a press, and more particularly to a technique for grasping the present condition of the load of a mechanical press.

[0002]

2. Description of the Related Art Among hydraulic presses, a hydraulic press allows the load during operation of the press to be directly visually recognized by a hydraulic pressure gauge, and the speed at which the load is applied is slow, so that there is little trouble in measuring the load, but mechanical In the case of a press, the load is impacted so that it is not so easy to visually recognize the dynamic load immediately, and there is an essential problem peculiar to this type of press.

As a measuring device originally included in a mechanical press, a load cell (strain gauge) or a dial gauge is fixed to a frame or a pillar of the press, which is generated in a mechanical structure such as a frame of the press in a load test. Means have been followed, such as measuring the strain that occurs, or detecting the pressure change that occurs in the built-in hydraulic system and electrically replacing them to know the load. However, the conventional conventional means has a problem in accurately measuring the load because a dynamic load is applied shockfully, and it is said that the shape of the molded product transferred to the mold is bilaterally symmetrical. The load is not limited to the eccentric load, because the load is not even on the entire surface, and the load is often uneven. In the forging press, multi-step dies are also widely applied, in which the dies of two or more steps are lined up in one die and the material is transferred in time with the forming, but in this case, each step is centered. Except for this, all are eccentric loads. Unless the eccentric load is accurately grasped and the bottom dead center is adjusted, there is a risk that unexpected overload will locally concentrate and cause distortion or cracks in the equipment, but the exact The problem is that measurement is finally difficult. Some proposals for solving this problem are also found.

For example, in Japanese Unexamined Patent Publication No. 54-20881, a load measuring unit 102 having a strain magnifying function is prepared by attaching a load cell 101 as shown in FIG.
Select two columns that are symmetrical with respect to the center point of the cross section of the mechanical press, select two positions that are further point symmetrical with respect to the center point of the cross section of the column, and measure the load at each selected position. It consists of mounting units and sending the output from each unit to a dynamic strain type load meter to measure the forging load. As a result, it was prevented that the load measurement was inaccurate, the bottom dead center was over adjusted, and the press mechanism was sometimes broken, and it was improved so that an accurate numerical value could be grasped even for eccentric load. I sing it.

[0005]

The mechanical press is such that the load is applied in a shocking short time. It is necessary to accurately measure the instantaneous load and adjust the bottom dead center. It is a more serious problem than the press. However, since the measuring device that should carry out its important function is fixed to somewhere in the press body, it is unavoidable to directly receive the intense vibration and high heat peculiar to the mechanical press. As a measuring device, which is a precision instrument, it is put under the most severe conditions,
There is a problem that the reliability of the measured value is rapidly lost with the operation of the press. In this regard, the prior art cited in FIG. 3 is no exception.

For this reason, a stable molding operation cannot be continued unless the reliability of the equipped measuring device itself is constantly checked. Therefore, maintenance work to eliminate this anxiety is an essential condition, and a forging site with advanced quality control is required. Then, over and over again, the work of inserting another hydraulic press into the load part of the mechanical press and confirming the correct load is repeated. FIG. 4 shows a conventional method for confirming measurement, in which a verification hydraulic cylinder 103 is fitted between the slide 2 and the bed 3 of the mechanical press main body 1 and the hydraulic cylinder 103 is inserted.
Is a pressure sensor 104, a hydraulic device 105, a measuring device 10.
6 is arranged to complete the measurement circuit. In this state, the mechanical press is operated to apply the load to the hydraulic cylinder, and the numerical value is converted and output to the measuring device.

This certification test requires extremely specialized skills and special equipment, and it is almost impossible to have it in a normal press factory. Therefore, the mechanical press manufacturer goes to the user upon request. The current situation is that it is implemented as part of after-sales service. The cost of this and the loss of stopping normal work for measurement,
In particular, it is unavoidable that the bottom of skilled measurers becomes a bottleneck and it is difficult to maintain and maintain the press sufficiently. A forging press with a large load requires a large-capacity hydraulic cylinder for verification, and of course the hydraulic system, which is an accessory device, is required to comply with this. To prepare various hydraulic cylinders for verification and bring them in to the customer,
It is still a heavy burden as a manufacturer's service. In the case of a forging press, measurement of eccentric load including the above-mentioned multi-step mold is always required, but there is no room to install the shaft center of a large-capacity hydraulic cylinder for verification at the eccentric position for measurement, and therefore eccentric load measurement It is also a big issue that space constraints are an obstacle.

In order to solve the above-mentioned problems, it is an object of the present invention to provide a method for measuring the current maximum load extremely easily in any shape mechanical press.

[0009]

The billet for verification of the press load test according to the present invention is a billet which has been machined into a uniform columnar shape having a uniform mechanical strength, and which has been confirmed in advance with respect to the load and plasticity of the press. The above problem was solved by giving a specific correlation with the amount of deformation.

As a method of using this verification billet, a specific verification billet is set at a desired position of a press load point, which is a device to be measured, and a pressure is applied to measure the plastic deformation amount of the verification billet. Then, it was proposed to calculate the load of the current press at the load point from a known specific relational expression.

[0011]

[Function] When calculating the load required for press forming, what kind of deformation resistance curve the target material has is an important issue, but the deformation resistance curve obtained in the material test is directly analyzed. Is complicated by the problem, and is sometimes impossible to analyze. Therefore, it is understood that it is practical to simplify the deformation resistance curve for calculation in the actual analysis. Various factors are intricately intertwined with the deformation resistance, and the main factors among them are the influence of strain, the influence of temperature, the influence of strain rate, and the like. The influence of strain appears as work hardening and is often set as δ = αβ ⁿ . Here, n is called a work hardening index, or n value, and is an element generated by strain of the lattice structure that occurs when the metal material undergoes plastic deformation during forming. In addition, α is a coefficient unique to metallic materials, and is determined by the micro- and macro-structures that appear differently depending on the contained components and heat history, especially the grain size and the flow of the structure, but the quality control was adequate. If the material is cut out from the same lot of steel and precisely finished to the same size, its α value is constant and it can be reliable even if it is incorporated as a measurement standard. The influence of strain rate is also one of the main factors, and within a certain strain rate range, the deformation resistance δ at a constant strain γ is
Often expressed as δ = Kγ ^m . Here, K is the deformation resistance at a unit strain rate, and m is called the strain rate dependence index. It is possible to combine these major factors as reasonably as possible to obtain a mathematical expression close to the actual one.
This is effective in actually calculating the load. What is generally accepted as this formula is

[0012]

[Equation 1] δ = αβ ⁿ γ ^m (Equation 1)

Here, δ: Deformation resistance of metal α: Unique value related to material β: Strain amount γ: Strain rate n: Work hardening index (index related to workability) m: Strain speed dependency index (related to processing speed) Index).

FIG. 1 is a diagram for explaining the operation of the present invention.
Whereas the above formula 1 is a general formula in plastic deformation of a metal material, a specific method for applying this general formula to a load test of a press is shown. Figure (A) shows a press, particularly a mechanical press 1 that can be expected to have a great effect. A cylindrical verification billet 4 is placed vertically between a slide 2 and a bed 3, and when the press is operated, the slide 2 descends by a stroke S. Then, the verification billet 4 is pressed to cause plastic deformation. As a result, the length H ₁ in the axial direction of the assay billet before deformation varies in length H ₂ as shown in FIG. (B), H ₁
-H ₂ = L is the amount upsetting during this time of press. The load T of the press can be determined by measuring the deformation resistance value of the verification billet during operation with a load cell or the like.

## EQU1 ## The various symbols constituting the equation 1 are shown in the left column, and the various factors during the deformation operation of the press are also shown in contrast with the right column. Δ: Press load: T α: Material of the test billet Element: M β ⁿ : Element related to upsetting amount: L γ ^m : Element related to slide speed (rotation speed of eccentric shaft): V That is, the load T of the press is related to the material M of the test billet and the deformation amount. Determined by the element L and the element V related to the processing speed,

[0016]

[Equation 2] T = f (MLV) ...... (Equation 2)

It can be seen that Among these, the element related to speed is a known value which is a unique value specified by the specifications of the press machine. The material-related factors can always be guaranteed to be reliable and constant values depending on the method of making the test billet. The preparation of the test billet requires a certain heat treatment to be adjusted to a uniform internal structure, and mechanical processing that satisfies a certain standard of surface roughness to always repeat the same plastic deformation under the same load. Becomes If these elements are constant, the function of the equation 2 is ultimately governed only by the element L relating to the deformation amount, so that the load of the press can be immediately calculated by measuring the upsetting amount.

[0018]

EXAMPLE An example of the present invention will be described. As a test billet, the material is a specified component in S30C, and a steel material that guarantees a specific mechanical strength by quenching and tempering according to the regulations A mass-produced product that is cut out and finished to a surface roughness that satisfies the precision finish of JIS is provided with the unique load-deformation relationship diagram (formula) confirmed in advance. The dimensions are cylindrical with a diameter of 110 mm and a height of 30 mm. In the measurement, as shown in FIGS. 1 and 2, an upper platen 5 is attached to the slide 2 of the mechanical press 1, a lower platen 6 is attached to the bed 3, and a load cell 7 is placed on the lower platen. The verification billet 4 is placed vertically on it and the press is operated. When it is necessary to measure the eccentric load, it goes without saying that the center axis of the verification billet is placed at the load point where the concentrated load is applied. The element related to the deformation amount is the upsetting amount L, and the element related to the deformation speed is the rotation speed of the press.

[0019]

[Table 1]

Table 1 shows the load T of the press and the speed V of the press,
And the upset amount L.
As a result, a significant correlation is clearly recognized between the load T of the press and the upsetting amount L of the verification billet, but between the press load and the press speed when the upsetting amount L is constant. No clear correlation was observed, and it was confirmed that the value of the press load T remains within the error of 3% for the same type of press even if the speed of the press is ignored. Therefore, in the end, as long as the accurate verification billet is applied, it can be easily calculated by operating the press and measuring the length of the upset amount L (= H ₁ −H ₂ ).

[0021]

As described above, according to the present invention, the current load of the mechanical press, which has the essential problem that the movement is particularly intense and the measurement is difficult and the measuring device is prone to error, is almost accurate by the simplest method. It is possible to capture in a range, and it is no longer necessary to apply a precise and large measuring device as in the past. Especially, the eccentric load, which is difficult to be measured, has a great benefit. Therefore, problems such as direct cost required to request certification and shortage of skilled personnel are solved all at once, and there is no vacant work due to stop of press required before and after instrument installation, certification, and removal. Also, it can contribute to the improvement of productivity. In addition, you can easily check the load so that you can check whether the attached load measuring device is displaying accurately, or you can easily measure the eccentric load that is difficult to avoid depending on the shape of the mold each time and adjust the load appropriately. (Movement of bottom dead center) can be completely applied,
There are various advantages such as preservation of damage due to unpredictable unbalanced load on the press.

[Brief description of drawings]

FIG. 1 is a front view showing the basic principle of the present invention by (A) and (B).

FIG. 2 is a front view showing an embodiment of the present invention.

FIG. 3 is a partial front view showing a conventional technique.

FIG. 4 is a front view showing another conventional technique.

[Explanation of symbols]

 1 Mechanical press 2 Slide 3 Bed 4 Test billet 5 Upper platen 6 Lower platen 7 Load cell

Claims (2)

[Claims] 1. A billet machined into a uniform cylindrical shape having a uniform mechanical strength and having a specific correlation between the load of the press and the amount of plastic deformation confirmed in advance. Billet for verification of load test. 2. A specific verification billet is set at a desired position of a press load point, which is a device to be measured, and is clamped, and the amount of plastic deformation of the verification billet is measured, and the specified billet is calculated from a known specific relational expression. A load test method for a press, which is characterized by calculating a current press load at a load point.