JPH04123868A - Brazing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding a brazing method using a gas burner etc., the purpose of stabilizing the joint strength and preventing a decrease in the strength of the base material is to gradually heat the joint by heating means. In the brazing method, the temperature of the joint is detected using a temperature sensor, and when the cumulative value of the period during which the temperature of the joint is equal to or higher than a first set temperature reaches a certain value, the heating means The temperature of the joint is increased to the melting temperature of the solder by increasing the thermal energy of the solder.

[Industrial application field]

The present invention relates to a brazing method using a gas burner or the like as a heating means.

The dot hammer in the print head of a dot impact printer is manufactured by brazing.

As printing speeds increase, there is an increasing demand for durability of dot hammers. Therefore, it is desired to stabilize the joint strength of brazing.

[Conventional technology]

FIG. 3 is an exploded perspective view of the dot hammer 2 at the manufacturing stage.

The dot hammer 2 is composed of a movable head 61 to which a plate spring 63 is attached, a dot pin 62, and the like.

The movable base 61 is obtained by press-molding a thin stainless steel plate, and has punched holes 61a to 61d for weight reduction. Further, at the tip of the movable head 61, there is a recess 61e for fixing the mounting position of the dot pin 62.
is provided.

Conventionally, the dot pin 62 has been attached as follows.

First, with the tip of the dot pin 62 engaged in the recess 61e, the movable base 61 and the dot pin 62 are supported as base materials for brazing, and the movable base 61 and the dot pin 62 are connected to each other.
The other parts are covered with a jig so as to expose the engaging part with the base material, that is, the joint part 2a of the base material.

Next, a paste brazing filler metal mixed with flux and wax is applied to the joint portion 2a using a dispenser.

Then, the joint portion 2a is heated with a gas burner,
Increase the firepower of the gas burner to allow enough time for the flux to melt. In other words, the heat is increased after a certain period of time has passed from the start of heating.

Thereafter, the gas burner is extinguished until the temperature of the joint 2a reaches the melting temperature of the wax, and the joint 2a is naturally cooled.

As a result, the movable head 61 and the dot pin 62 are joined by solder.

A flat coil or the like is attached to the movable heir 61 after the dot pin 62 is brazed, and the completed dot hammer 2 is assembled to the base of the print head in a set of, for example, 24 dot hammers.

[Problem to be solved by the invention]

As described above, conventionally, in order to utilize flux, two-stage heating (heating power adjustment) has been performed on the joint 2a in consideration of the respective melting temperatures of the flux and the wax.

However, in the past, the heating power adjustment for temperature control was performed based only on the management of the elapsed time from the start of heating. Due to the variation in temperature, the temperature transition characteristics of the joint portion 2a may deviate from the expected characteristics.

For this reason, there has been a problem in that the flux or wax is not sufficiently melted or the amount is insufficient due to evaporation, resulting in a bonding failure in which a predetermined bonding strength or bonding itself cannot be obtained. Further, there is a problem in that the strength of the base material such as the dot pin 62 is reduced due to excessive heating.

In view of the above-mentioned problems, the present invention aims to stabilize the bonding strength and prevent the strength of the base material from decreasing.

[Means to solve the problem]

In order to solve the above-mentioned problem, the method according to the invention of claim I includes a brazing method in which the joint part 2a is heated in stages by the heating means 30, as shown in FIGS. 40 is used to detect the temperature of the joint part 2a, and the heating is performed at time t6 when the integrated value of Ta, Tb, and Tc reaches a constant value T1 during the period during which the temperature of the joint part 2a is equal to or higher than the first set temperature TMI. Brazing is performed by increasing the thermal energy of the means 30 and raising the temperature of the joint 2a to the melting temperature of the solder.

As shown in FIGS. 1 and 2, the method according to the invention of claim 2 is provided at a time point L7 when the temperature of the joint portion 2a is increased to reach a second set temperature TM2 higher than the first set temperature TMI. The heating by the heating means 30 is stopped at time t8 when a certain period of time T2 has elapsed.

[For production]

The heating means 30 starts heating the joint portion 2a.

The temperature of the joint 2a is detected by a temperature sensor 40.

During the period during which the temperature of the joining part 2a is higher than the first set temperature TMI, the integrated value of Ta, Tb, and Tc reaches a constant value T1, and at a time t6 when the flux is sufficiently melted, the thermal energy of the heating means 30 is strengthened, and the joining is completed. The temperature of the portion 2a increases.

The temperature of the joint part 2a is higher than the first set temperature TMI.
At time t8, when a predetermined time T2 has elapsed from time t7 when the set temperature TM2 is reached and the wax melts, heating is stopped and brazing is completed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of the brazing apparatus 1 according to the embodiment of the present invention.

The brazing apparatus 1 includes a control section 10, a gas generator 20, a burner section 30, an infrared temperature sensor 40, and a temperature recorder 50 for recording the progress of temperature control.

The control unit 10 sends control signals S33,
It consists of a thermal power controller 11 that outputs 34.35, a temperature determination section 12, and an integration timer 13.

The gas generator 20 generates hydrogen gas (H2
), a cooler 22, an atomizer 23 for increasing the reducibility of hydrogen gas, and a drain trap 24, and supplies hydrogen gas to the burner section 30.

The burner section 30 has a main burner 31 and a pilot burner 32, and the ignition and firepower adjustment of these burners 31 and 32 are performed by electromagnetic on-off valves 33, 34, 35 and pressure reducing valves 36S, 36M, 3
Performed by 6P. That is, in the brazing device 1,
The heat power of the main burner 31 is adjusted in three stages: low heat, medium heat, and high heat, and a control signal S33 is output according to the selection of the heat power.
, 3435, the electromagnetic on-off valves 33, 34, and 35 are alternatively opened. Further, the pilot burner 32 is always kept in the ignited state, and its thermal power is reduced to the minimum level for igniting the main burner 31 by the pressure reducing valve 36P.

The burner unit 30 includes a backfire filter 37 that prevents the flame of the main burner 31 from spreading in the opposite direction, and a pressure gauge 38.
is provided.

Next, a method of brazing using the brazing apparatus 1 will be described, taking as an example the manufacture of the above-mentioned don't hammer 2 (see FIG. 3).

FIG. 1 is a diagram showing a brazing method according to the present invention.

Referring also to FIGS. 2 and 3, in the brazing procedure, first, don't hammer 2, which is a base material, is placed so that its joint 2a is located above the crater of main burner 31.

That is, the movable base 61 is placed on a support stand (not shown) so that the recess 61e is located above the main burner 31,
The tip of the dot pin 62 is engaged with the recess 61e while the dot pin 62 is supported by a holding means (not shown). Then, parts other than the joint 2a are shielded from the flame of the main burner 31 using a suitable jig.

Next, an appropriate amount of a paste-like brazing material, which is a mixture of wax and flux, is applied to the joint portion 2a using a dispenser or the like.

After arranging the base material and the brazing material as described above, the control unit 10
When the start switch 15 is turned on, the thermal power controller 1
1 outputs a control signal S34, the solenoid valve 34 is opened, and the main burner 31 is ignited with medium heat. This results in
The joint portion 2a is heated.

The infrared temperature sensor 40 detects the temperature of the joint 2a,
The temperature determination unit 12 determines that the temperature of the junction 2a is a first set temperature TM based on the output signal S1 of the infrared temperature sensor 40.
Determine whether or not I has been reached. Here, the first set temperature T
MI is the melting temperature of the flux (600°C).

When the temperature of the joint 2a reaches the first set temperature TMI, the thermal power controller 11 adjusts the thermal power of the main burner 31 to maintain the first set temperature TMI for a predetermined time in order to sufficiently melt the flux. That is, the joint part 2a
Time tl, t3. when the temperature exceeds 600°C. t5
The main burner 31 is set to low heat at t2. At t4, control is performed to return the main burner 31 to medium heat.

Incidentally, even if the temperature of the flux drops slightly below 600° C., the entire flux does not solidify immediately and remains in a state extremely close to a molten state as a whole.

In conjunction with the adjustment of the thermal power of the main burner 31, the integration timer 13 integrates the lengths (time) of periods Ta, Tb, and Tc during which the temperature of the joint portion 2a is 600° C. or higher. and,
The thermal power controller 11 switches the main burner 31 to high heat at time L6 when the integrated value of the integrated timer 13 reaches a predetermined value Tl (about 1.5 seconds), and sets the joint 2a to the second set temperature T.
Rapidly heat to M2 (wax melting temperature 2670°C). When the temperature of the joint 2a reaches 670°C, the main burner 31 is switched to low heat in order to suppress unnecessary temperature rise. At the same time, the integration timer 13
The thermal power controller 11 starts integrating the length of the period during which the temperature of At time L8, the main burner 3I is extinguished.

As a result, the temperature at the joint 2a is 670°C.
At point t7, the wax and flux combine,
It gets into the gap between the movable heath 61 and the dot bin 62,
With the subsequent natural cooling, the movable heir 61 and the dot bin 62 are joined.

According to the above-described embodiment, when heating the joint 2a in stages, at each stage (stages before and after time L6), the temperature serving as a reference for switching the thermal power of the main burner 31 and the integration timer 13 are determined. Since the reference temperatures at the start and end of the integration are the same value (600°C, 670°C), compared to the case where the reference temperature is set separately for switching the heating power and integrating the time, The logic or program of the control unit 10 can be simplified.

In the above-described embodiment, the timing at which the integration timer 13 starts or ends the integration and the timing at which the thermal power controller 11 switches the thermal power are made to match, but these timings can be made independent. In other words, the integration timer 13 calculates each set temperature TM.
I, TM2 may be used as a reference, and the heating power may be switched using a separately set temperature as a reference. For example, to prevent the temperature of the joint 2a from dropping below 600°C while waiting for the flux to melt, the reference temperature for switching the heating power is set higher than 600°C (for example, 610°C).
Can be set to .

In the embodiments described above, the times T1 and T2 can be appropriately selected depending on the heat capacity of the base material, the material and amount of the brazing filler metal, and the like. Further, the thermal power of the main burner 31 may be adjusted in four or more steps or steplessly to control the temperature of the joint portion 2a more precisely.

〔Effect of the invention〕

According to the present invention, it is possible to stabilize the bonding strength by eliminating excessive or insufficient heating of the bonded portion, and it is possible to prevent a decrease in the strength of the base material.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a brazing method according to the present invention, FIG. 2 is a block diagram showing the configuration of a brazing apparatus according to the present invention, and FIG. 3 is an exploded perspective view of a dot hammer in a manufacturing stage. In the figure, 2a is a joint, 30 is a burner part (heating means), 40 is an infrared temperature sensor (temperature sensor), TI is a constant value, T2 is a certain time, TMI is the first set temperature, TM2 is the second set temperature, t6 t7°L8 are time points.

Claims (2)

[Claims] (1) A brazing method in which the joint part (2a) is heated in stages by the heating means (30), which includes: detecting the temperature of the joint part (2a) using a temperature sensor (40); ) is equal to or higher than the first set temperature (TM1). At the time (t6) when the integrated value of (Ta), (Tb), and (Tc) reaches a certain value (T1), the heating means (30
) A brazing method characterized in that brazing is performed by increasing the thermal energy of step (2a) and raising the temperature of the joint (2a) to the melting temperature of the solder. (2) Raise the temperature of the joint part (2a) to
It is characterized by stopping the heating by the heating means (30) at the time (t8) when a certain period of time (T2) has elapsed from the time (t7) when a second set temperature (TM2) higher than the set temperature (TM1) is reached. The brazing method according to claim 1.