Temperature control method for self-resistance heating rivet

Abstract

The invention relates to a temperature control method for a self-resistance heating rivet. The problem that the temperature of a titanium alloy rivet is not easy to control accurately is solved. A hole is formed in the test piece; the rivet is placed in the formed hole; the jacking iron and the rivet shell of the self-resistance heating device abut against the front end and the rear end of the rivet correspondingly; a metal wire temperature sensor is attached to the center of the rivet rod; selecting a riveting rivet diameter D and an output voltage V; starting a rivet heating function by using a riveter switch, and shooting the indicating value of the temperature sensor at the rivet rod and the time change at the same time; a curve of rivet temperature changing along with time is made; the heating device is automatically powered off after the set time is up; the riveting work is started at the moment of power failure; checking whether the internal structure of the rivet meets the strength requirement or not; and determining the optimal heating time process parameters of the titanium alloy rivet with a certain diameter D when the output voltage is V. The temperature in the operation process is controllable, and the quality is reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of high-temperature resistant and high-strength rivet riveting, and relates to a temperature control method for a self-resistance heating rivet. Background Art

[0002] In recent years, domestic aviation equipment has developed rapidly. In order to adapt to high temperature and high strength working conditions, the connection method of the fuselage structure has been continuously innovated and developed. Titanium alloy rivets have become the main choice of riveting fasteners for the fuselage structure of aviation equipment products due to their high temperature resistance and shear resistance and tensile resistance at high temperatures. Titanium alloy rivets generally have the characteristics of poor plasticity and strong brittleness at room temperature. Most titanium alloy rivets cannot be hammer-riveted at room temperature, and there is a lack of reliable hammer-riveting devices and methods for titanium alloy rivets.

[0003] Hammer riveting is a method of forming a pier head by means of the impact force of the rivet gun and the impact of the top iron. In the aviation manufacturing industry, manual riveting equipment is mainly pneumatic riveting guns. The rivet gun is connected to the industrial air source (0.6Mpa~0.8Mpa) during the working process, and the internal mechanism is driven by air pressure to output rhythmic telescopic movement to form hammer riveting power. In the actual riveting process, the second person uses special equipment to hold the nail rod to form a pier head.

[0004] Research has shown that different types of titanium alloy rivets have their optimal temperature range for plasticity. The process of forming the pier head is relatively labor-saving, and it is the best time for hammer riveting. Summary of the invention

[0005] The present invention solves the problem that the temperature of titanium alloy rivets is difficult to accurately control by providing a self-resistance heating rivet temperature control method.

[0006] The present invention is achieved by the following technical solutions:

[0007] A temperature control method for self-resistance heating rivets includes an automatic voltage regulator and an automatic timer. The automatic voltage regulator reduces the 220V input voltage to 3V, 4V, and 5V output voltages. When the heating time T of a rivet of a certain specification is too long, the voltage V can be slightly increased to reduce the riveting waiting time T1 and improve efficiency. When the heating time of a rivet of a certain specification is very short, the output voltage can be reduced and the heating time can be slightly increased to give the riveting operation a certain interval or preparation time. The automatic timer is used to synchronously record the temperature-time relationship from the start of heating to the time when the rivet reaches the best plastic state and form a temperature curve that changes with time. The specific steps are:

[0008] 1) Prepare the test piece and make holes on it;

[0009] 2) Prepare the rivet and place it in the prepared hole;

[0010] 3) Use the top iron and rivet shell of the self-resistance heating device to respectively press against the front and rear ends of the rivet;

[0011] 4) Stick the wire temperature sensor to the center of the rivet rod;

[0012] 5) Select the riveting rivet diameter D and output voltage V;

[0013] 6) Turn on the power of the self-resistance heating device and use the rivet gun switch to turn on the rivet heating function;

[0014] 7) Use video recording to simultaneously shoot the temperature sensor indication and time changes at the rivet rod;

[0015] 8) Make a rivet temperature change curve over time based on the shooting records, and determine the corresponding heating time in combination with the optimal plastic temperature of the rivet material;

[0016] 9) Select a fixed heating time in the control system, and set the heating time to the rivet heating time specified in step 8. After the heating switch is turned on and heating is started, the heating device automatically cuts off power after the specified time is reached;

[0017] 10) Operators cooperate with each other and start riveting work at the moment of power failure when the heating time is reached;

[0018] 11) Carry out metallographic testing on the test piece to check whether the internal structure of the rivet meets the strength requirements;

[0019] 12) After going through the repeated process of rivet heating - making curves - obtaining the optimal heating time - riveting - rivet testing, the optimal heating time process parameters of a titanium alloy rivet with a certain diameter D when the output voltage is V are finally determined.

[0020] The present invention realizes the heating temperature control of titanium alloy rivets without changing the use mode of traditional pneumatic tool hammer riveting, can realize the process requirement of riveting work in the optimal plasticity stage, meets the riveting needs under the conditions of manual hammer riveting, has controllable temperature during the operation process, reliable quality, and can be widely used in titanium alloy rivet process verification. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of the implementation of a self-resistance heating temperature control method of the present invention. DETAILED DESCRIPTION

[0022] The present invention aims to design a self-resistance heating rivet temperature control system to address the technical difficulties of titanium alloy rivets, such as low plasticity and poor riveting processability at room temperature, and easy occurrence of cracks, fractures, etc. The time required to reach the optimal riveting temperature is verified for rivets of different specifications and diameters, forming a temperature change curve of the rivet over time, improving the precise control of the automatic heating time of rivets of different specifications during the hot riveting process, and standardizing the control of rivet temperature changes over time.

[0023] The diameters of rivets used on a large scale in the aviation manufacturing field are generally Φ2.5mm, Φ3mm, Φ4mm, Φ5mm, Φ6mm, etc. As the diameter of the rivet increases, the difficulty of forming the pier head also increases. Titanium alloy rivets have low plasticity at room temperature and poor riveting processability. They need to be heated to improve their plasticity before riveting work can be carried out to achieve a high-strength rivet connection process.

[0024] 1) Automatic voltage regulator: On the one hand, in order to ensure personal safety during on-site operations, and on the other hand, combined with a large amount of test data and the intermittent frequency of on-site hammer riveting, the system reduces the 220V input voltage to 3V, 4V, and 5V output voltages. The output voltage can be changed by manipulating the interactive interface in the human-computer interaction interface. When the heating time T of a certain specification of rivets is too long (it takes a long time to reach the ideal plastic state), the voltage V can be slightly increased to reduce the riveting waiting time T1 and improve efficiency. When the heating time of a certain specification of rivets is very short (it takes a short time to reach the ideal plastic state and there is no time for riveting operations), the output voltage can be reduced, the heating time can be slightly increased, and a certain interval or preparation time can be given to the riveting operation.

[0025] 2) Automatic timer: After the system is powered on, the temperature of the rivet increases over time, and the plasticity increases. The automatic timer is used to synchronously record the temperature-time relationship from the start of heating to the time when the rivet reaches the optimal plastic state and form a temperature curve that changes over time. When the operator determines that the rivet has reached the optimal temperature, riveting is carried out. After multiple riveting tests and rivet quality inspections after riveting, the heating time for the test rivet to reach the optimal plasticity is finally confirmed.

[0026] See also Figure 1 , which shows a flow chart of the implementation of a self-resistance heating temperature control method of the present invention.

[0027] Implementation process:

[0028] 1) Prepare the test piece and make holes in it according to the test plan.

[0029] 2) Prepare the D rivet and place it in the prepared hole.

[0030] 3) Use the top iron and rivet shell of the self-resistance heating device to press against the front and rear ends of the rivet respectively.

[0031] 4) Stick the wire temperature sensor in the center of the rivet rod.

[0032] 5) Select the riveting rivet D and output voltage V on the control interface.

[0033] 6) Turn on the power of the self-resistance heating device and use the rivet gun switch to turn on the rivet heating function.

[0034] 7) Use video recording to simultaneously capture the temperature sensor reading and time changes at the rivet rod.

[0035] 8) Make a rivet temperature change curve over time based on the shooting records, and determine the corresponding heating time in combination with the optimal plastic temperature of the rivet material.

[0036] 9) Select a fixed heating time in the control system and set the heating time to the rivet heating time specified in step 8. After the heating switch is turned on and heated, the heating device will automatically shut down after the specified time.

[0037] 10) Operators cooperate with each other and start riveting work at the moment of power failure when the heating time is reached.

[0038] 11) Carry out metallographic testing on the test pieces to check whether the internal structure of the rivets meets the strength requirements.

[0039] 12) After going through the repeated process of rivet heating - making curves - obtaining the optimal heating time - riveting - rivet testing, the optimal heating time process parameters of a titanium alloy rivet with a certain diameter D when the output voltage is V are finally determined.

[0040] Through the above steps, the rivet temperature can be accurately controlled, the best plasticity timing can be grasped, the riveting process can be improved, the riveting work of titanium alloy rivets can be completed, and the riveting efficiency and one-time success rate can be improved.

Claims

1. A temperature control method for a self-resistance heating rivet, characterized in that: It includes an automatic voltage regulator and an automatic timer. When the heating time T of a certain specification rivet is too long, the automatic voltage regulator can slightly increase the voltage V, reduce the riveting waiting time T1, and improve efficiency; when the heating time of a certain specification rivet is very short, the output voltage can be reduced, the heating time can be slightly increased, and a certain interval or preparation time can be given to the riveting operation; the automatic timer is used to synchronously record the temperature-time relationship from the start of heating to the time when the rivet reaches the best plastic state and form a temperature curve that changes with time; the specific steps are: 1) Prepare the test piece and make holes on it; 2) Prepare the rivet and place it in the prepared hole; 3) Use the top iron and rivet shell of the self-resistance heating device to respectively press against the front and rear ends of the rivet; 4) Stick the wire temperature sensor to the center of the rivet rod; 5) Select the riveting rivet diameter D and output voltage V; 6) Turn on the power of the self-resistance heating device and use the rivet gun switch to turn on the rivet heating function; 7) Use video recording to simultaneously shoot the temperature sensor indication and time changes at the rivet rod; 8) Make a rivet temperature change curve over time based on the shooting records, and determine the corresponding heating time in combination with the optimal plastic temperature of the rivet material; 9) Select a fixed heating time in the control system, and set the heating time to the rivet heating time specified in step 8. After the heating switch is turned on and heating is started, the heating device automatically cuts off power after the specified time is reached; 10) Operators cooperate with each other and start riveting work at the moment of power failure when the heating time is reached; 11) Carry out metallographic testing on the test piece to check whether the internal structure of the rivet meets the strength requirements; 12) After going through the repeated process of rivet heating - making curves - obtaining the optimal heating time - riveting - rivet testing, the optimal heating time process parameters of a titanium alloy rivet with a certain diameter D when the output voltage is V are finally determined.

2. A self-resistance heating rivet temperature control method according to claim 1, characterized in that: The automatic voltage regulator reduces the 220V input voltage to 3V, 4V, or 5V output voltage.

3. A self-resistance heating rivet temperature control method according to claim 1 or 2, characterized in that: Control the interactive interface in the human-machine interface to change the output voltage.

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