阅读说明：本技术 一种基于铆接曲线的钢铝混合车身自冲孔铆模寿命的监测方法 (Method for monitoring service life of self-punching riveting die of steel-aluminum hybrid vehicle body based on riveting curve ) 是由 刘蕾 梁端 汤东华 于 2019-09-06 设计创作，主要内容包括：本发明公开了一种基于铆接曲线的钢铝混合车身自冲孔铆模寿命的监测方法,包括以下步骤：通过压力传感器实时监测铆接压力值至监测主机；在监测主机中输入铆接组合的材料信息、铆钉信息、铆模信息；根据铆钉信息和铆模信息计算出钉模容积比c；根据材料信息、铆接压力、钉模容积比c调用经验数据库查询铆模寿命影响因素a；利用公式计算铆模当前寿命N<Sub>R</Sub>,当N<Sub>R</Sub>小于设定值时,进行更换铆模的预警。本发明实时监测铆接压力曲线的变化,从而得出影响铆模的因素,根据铆接压力、钉模容积比、以及板材信息计算出铆模的当前寿命,并提前预警,避免铆模损坏无法发现,保证白车身铆接质量。(The invention discloses a method for monitoring the service life of a self-punching riveting die of a steel-aluminum hybrid vehicle body based on a riveting curve, which comprises the following steps of: monitoring a riveting pressure value to a monitoring host machine in real time through a pressure sensor; inputting material information, rivet information and riveting die information of riveting combination in a monitoring host; calculating a nail mold volume ratio c according to the rivet information and the rivet mold information; calling an experience database to inquire a riveting die life influence factor a according to the material information, the riveting pressure and the nail die volume ratio c; calculating the current service life N of the riveting die by using a formula R When N is present R And when the rivet die is smaller than the set value, early warning of replacing the rivet die is carried out. The method and the device monitor the change of the riveting pressure curve in real time, thereby obtaining factors influencing the riveting die, calculating the current service life of the riveting die according to the riveting pressure, the volume ratio of the riveting die and the plate information, giving early warning, avoiding the situation that the damage of the riveting die cannot be found, and ensuring the riveting quality of the white automobile body.)

1. A method for monitoring the service life of a self-punching riveting die of a steel-aluminum hybrid vehicle body based on a riveting curve is characterized by comprising the following steps:

the method comprises the following steps: monitoring a riveting pressure value to a monitoring host machine in real time through a pressure sensor;

inputting material information, rivet information and riveting die information of riveting combination in a monitoring host;

step three, calculating a nail mold volume ratio c according to the rivet information and the rivet mold information, wherein c is V_{Rivet volume}/V_{Volume of riveting die}；

Calling an experience database to inquire the influence factor a of the service life of the riveting die according to the material information, the riveting pressure and the volume ratio c of the riveting die;

step five, calculating the current service life of the riveting die

step six, when N is reached_RAnd when the rivet die is smaller than the set value, early warning of replacing the rivet die is carried out.

2. The method for monitoring the service life of the self-piercing riveting die of the steel-aluminum hybrid vehicle body based on the riveting curve according to claim 1, wherein the set value is an integral multiple of a beat value.

3. The method for monitoring the service life of the self-piercing riveting die of the steel-aluminum hybrid vehicle body based on the riveting curve as recited in claim 1, wherein the riveting combination is a multilayer board, and the material information of the multilayer board is the tensile strength, the yield strength and the elongation of each layer of board.

Technical Field

The invention relates to a self-piercing riveting process, in particular to a method for monitoring the service life of a self-piercing riveting die of a steel-aluminum hybrid vehicle body based on a riveting curve.

Background

The self-piercing riveting process is called SPR for short, and is one of the common processes for connecting aluminum alloy vehicle bodies. The SPR is a brand new plate connection technique in which a rivet is directly pressed into a plate to be riveted by a power supplied from a hydraulic cylinder or a servo motor, the plate to be riveted is plastically deformed with the rivet under the pressure of the rivet, and the formed plate is filled in a riveting die, thereby forming stable connection, as shown in fig. 1.

Whether the riveting quality is qualified or not plays an important role. In the riveting process, if the riveting die has cracks, cracks and gaps, the riveting quality is unqualified. If the riveting die cannot be damaged in the process of batch production of the line body, the condition that the batch white car bodies are unqualified can be caused, and even the serious consequence of the scrapping of the white car bodies can be caused.

At present, the conventional inspection method of the riveting die is as follows:

1) before production shifts, the workers enter a line body to visually check;

2) the mode of using the mould of riveting to shoot discerns the damaged condition of riveting the mould, but the error is great, can appear a large amount of wrong report information like this moreover, leads to the line body often to report by mistake, influences the automated production of line body, and the rate of utilization of this method is very low.

In order to ensure the riveting quality and not influence the production of a production line, a more accurate monitoring method for the damage of the riveting die needs to be used.

Disclosure of Invention

The invention aims to provide a method for monitoring the service life of a self-punching riveting die of a steel-aluminum hybrid vehicle body based on a riveting curve, so as to monitor the service life of the riveting die on line.

Therefore, the invention provides a method for monitoring the service life of a self-punching riveting die of a steel-aluminum hybrid vehicle body based on a riveting curve, which comprises the following steps of: the method comprises the following steps: monitoring a riveting pressure value to a monitoring host machine in real time through a pressure sensor; inputting material information, rivet information and riveting die information of riveting combination in a monitoring host; step three, calculating a nail mold volume ratio c according to the rivet information and the rivet mold information, wherein c is V_{Rivet volume}/V_{Volume of riveting die}(ii) a Step four, according to the material informationCalling an experience database to inquire a riveting die life influence factor a by using riveting pressure and a nail die volume ratio c; step five, calculating the current service life of the riveting die

Wherein, F_avgIs the mean value of pressure, F_RThe actual pressure of one riveting is shown, N is the riveting frequency, and N is the theoretical service life of the riveting die; step six, when N is reached_RAnd when the rivet die is smaller than the set value, early warning of replacing the rivet die is carried out.

The method and the device monitor the change of the riveting pressure curve in real time, thereby obtaining factors influencing the riveting die, calculating the current service life of the riveting die according to the riveting pressure, the volume ratio of the riveting die and the plate information, giving early warning, avoiding the situation that the damage of the riveting die cannot be found, and ensuring the riveting quality of the white automobile body.

In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic illustration of a prior art self-piercing riveting process;

FIG. 2 is a schematic illustration of a riveting pressure curve recorded by a monitoring host for a certain punch rivet; and

FIG. 3 is a flow chart of a method for monitoring the service life of a steel-aluminum hybrid vehicle body self-piercing riveting die based on a riveting curve according to the invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The invention discloses a calculation method for monitoring the change of a riveting pressure curve in real time so as to obtain factors influencing a riveting die and calculate the service life of the riveting die. And calculating the residual service life of the riveting die according to the real-time change of the riveting pressure curve, the volume ratio of the riveting die and the plate information, and giving early warning in advance to avoid the phenomenon that the riveting die is damaged and cannot be found, thereby ensuring the riveting quality of the white automobile body.

The invention provides a method for monitoring the service life of a riveting die, which is applied to a self-piercing riveting process, and the method comprises the following basic principles and steps as shown in figure 3:

and S11, monitoring the riveting pressure value in real time through the pressure sensor and feeding back the pressure value to the monitoring host.

Fig. 2 shows a riveting pressure curve of a certain punch riveting, and the riveting curve (new envelope line) is a curve of pressure variation of a guide rod during the relative position of a guide rod and a pressing block of the riveting equipment from large to small (6 mm to-1 mm in fig. 2) in the riveting process.

Fig. 2 also shows an old envelope curve, where the old envelope curve is a theoretical riveting curve, the new envelope curve is an actual riveting pressure curve during the previous riveting, the maximum pressure value of the new envelope curve is smaller than the pressure value of the theoretical riveting curve, and the maximum pressure value may be larger than the theoretical pressure value or may be smaller than or equal to the theoretical pressure value during the other riveting.

And S12, inputting the material information (including strength and elongation), the rivet information and the riveting die information of the riveting combination into the monitoring host. The riveting combination is a multilayer board, and the material information of the multilayer board is the tensile strength, the yield strength and the elongation of each layer of board.

S13, calculating the volume ratio c of the rivet mold according to the information of the rivet and the riveting mold, wherein the calculation formula is as follows:

wherein, V_{Rivet volume}Refers to the solid volume of the rivet, V_{Volume of riveting die}Refers to the volume of the cavity of the riveting die.

And S14, calling an experience database to inquire the riveting die life influence factor a according to the material information, the riveting pressure and the nail die volume ratio c.

Examples of this empirical database are as follows:

in the invention, the influence factor a of the riveting die life under actual pressure is obtained through experiments.

S15, calculating the current service life of the riveting die:

the service life of the theoretical riveting die is N; actual life N_R(ii) a Mean value of pressure F_avg(ii) a Actual pressure F of riveting once_RAnd N is the riveting times, the current service life of the riveting die is N_RThe calculation formula of (a) is as follows:

wherein the pressure mean value F_avgIs the riveting pressure value (i.e. the maximum value in the theoretical riveting curve) corresponding to the theoretical riveting pressure curve, F_RIs the riveting pressure value of the current riveting (i.e. the maximum value in the riveting curve of the current riveting).

S16 early warning of replacement of riveting die

N_RWill gradually decrease as the number of riveting increases. When N is present_RWhen the value of (2) is less than the set value, for example, 10, the riveting die is reminded to be replaced.

The set value is an integer multiple of the beat value, for example, when the beat value is 10, the set value may be selected to be an integer multiple of 10, such as 10 or 20.