Automatic welding method

Abstract

The invention provides an automatic welding method, and relates to the technical field of single crystal drawing. The method comprises the following steps: visually identifying a seed crystal to judge whether the seed crystal is new or old; inserting the seed crystal for the first time until the seed crystal is in contact with the liquid level, and then inserting for the second time; detecting the diameter of the seed crystal for the first time, and inserting the seed crystal for the third time if the diameter of the seed crystal is unqualified; detecting the diameter of the seed crystal for the second time, and inserting the seed crystal for the fourth time if the diameter of the seed crystal is unqualified; the new seed crystal is directly inserted downwards to be in contact with the liquid level, and the old seed crystal is firstly inserted downwards to the last welding position and then is inserted downwards to be in contact with the liquid level; in the first seed crystal diameter detection process, the second seed crystal diameter detection process and the fourth seed crystal downward insertion process, if the seed crystal diameter is qualified, welding is started, and then power reduction is started to achieve cooling; and arranging an electrode electrically connected with the seed crystal, and monitoring the voltage of the electrode to judge whether the seed crystal is in contact with the melt. The device is high in automation degree, and human factors such as operation errors are reduced so as to avoid influence on subsequent procedures.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal pulling, and in particular to an automatic welding method. Background Art

[0002] In the single crystal pulling process, many manufacturers are still manually operating the welding process. The manually operated welding process may have abnormalities such as failure to preheat and failure to cool down in time during the welding process due to various reasons. In addition, when there are a large number of furnaces under the on-site main operator or centralized control, various abnormal situations are more likely to occur. The occurrence of abnormalities affects the subsequent processes, resulting in an increase in wire breaks and more invalid working hours. Summary of the invention

[0003] The purpose of the present invention is to develop an automatic welding method with high automation, which can reduce human factors such as operation errors and avoid affecting subsequent processes.

[0004] The present invention is achieved through the following technical solutions:

[0005] An automatic welding method comprises the following steps:

[0006] S1. Visually identify the seed crystal to determine whether the seed crystal is a new seed crystal or an old seed crystal;

[0007] S2. After the seed crystal is inserted into the liquid surface for the first time, it is inserted into the liquid surface for the second time;

[0008] S3. Perform the first seed crystal diameter test. If the seed crystal diameter fails, the seed crystal is inserted for the third time;

[0009] S4. Perform a second seed crystal diameter test. If the seed crystal diameter fails to meet the requirements, the seed crystal is inserted for the fourth time.

[0010] Wherein, in step S2, the new seed crystal is directly inserted down until it contacts the liquid surface, and the old seed crystal is first inserted down to the last fusion position, and then inserted down again until it contacts the liquid surface;

[0011] During the first seed crystal diameter detection in step S3, the second seed crystal diameter detection in step S4, and the fourth seed crystal insertion process, if the seed crystal diameter is qualified, welding is started, and then the power is reduced to achieve cooling;

[0012] An electrode electrically connected to the seed crystal is provided, and the electrode voltage is monitored to determine whether the seed crystal is in contact with the melt.

[0013] Optionally, in step S1, the new seed crystal and the old seed crystal are distinguished by identifying or detecting the shape and surface smoothness of the seed crystal. The old seed crystal has fine crystals and necking left after the last seeding, and there are conical residues at the bottom of the old seed crystal and its surface smoothness is low.

[0014] Optionally, a set diameter 1 of the seed crystal is set in advance. When the seed crystal diameter is ≥ the set diameter 1, the seed crystal diameter is qualified; when the seed crystal diameter is < the set diameter 1, the seed crystal diameter is unqualified.

[0015] Optionally, the set diameter 2 of the seed crystal is set in advance. If the seed crystal diameter is qualified, after the welding starts, when the seed crystal diameter reaches the set diameter 2, the power starts to be reduced to achieve cooling. The set diameter 2 is reached after the set diameter 1 shrinks by 0.5 mm.

[0016] Optionally, the lowest seed crystal position 1 is set in advance. In step S2, when the seed crystal is inserted to the lowest seed crystal position 1 for the first time, if the seed crystal has not yet contacted the liquid surface, the insertion is stopped and an alarm is issued for manual intervention.

[0017] Optionally, the lowest seed crystal position 2 is set in advance. In step S4, when the seed crystal is inserted to the lowest seed crystal position 2 for the fourth time, if the seed crystal diameter is still unqualified, the seed crystal stops being inserted and an alarm is issued.

[0018] Optionally, when the electrode voltage is monitored, when the electrode voltage is a stable value, the seed crystal is not in contact with the melt, and when the electrode voltage suddenly changes, the seed crystal is in contact with the melt.

[0019] Optionally, a tungsten wire rope is connected to the seed crystal, and the electrode is electrically connected to the tungsten wire rope.

[0020] Optionally, in step S2, the second insertion is 3 mm.

[0021] Optionally, in step S3, the third insertion is performed by 3 mm.

[0022] The beneficial effects of the present invention are:

[0023] The present invention reduces manual operation items, has a high degree of automation and high operating efficiency. It does not require manual operation for operations such as inserting seed crystals and cooling, and automatically realizes welding, thereby reducing abnormal situations caused by human factors such as operating errors, and avoiding affecting subsequent processes. Visual recognition is used to distinguish new seed crystals from old seed crystals, and corresponding insertion operations are automatically performed according to the conditions of the seed crystals. The contact condition between the seed crystals and the melt is judged by using contact voltage, and the judgment result is accurate, which prevents excessive insertion of seed crystals due to visual misjudgment, and protects the seed crystals and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0026] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] like Figure 1 As shown, the present invention discloses an automatic welding method, comprising the following steps:

[0029] S1. Visually identify the seed crystal to determine whether the seed crystal is a new seed crystal or an old seed crystal;

[0030] S2. After the seed crystal is inserted into the liquid surface for the first time, it is inserted into the liquid surface for the second time by 3 mm.

[0031] S3. Perform the first seed crystal diameter test. If the seed crystal diameter fails, the seed crystal is inserted 3 mm for the third time;

[0032] S4. Perform a second seed crystal diameter test. If the seed crystal diameter fails to meet the requirements, the seed crystal is inserted for the fourth time.

[0033] Among them, in step S1, the new seed crystal and the old seed crystal are judged by identifying or detecting the shape and surface smoothness of the seed crystal. The old seed crystal has fine crystals and necking left after the last seeding. The old seed crystal has a cone-shaped residue at the bottom and its surface smoothness is low.

[0034] In step S2, the new seed crystal is directly inserted down until it contacts the liquid surface, and the old seed crystal is first inserted down to the last fusion position, and then inserted down again until it contacts the liquid surface;

[0035] During the first seed crystal diameter detection in step S3, the second seed crystal diameter detection in step S4, and the fourth seed crystal insertion process, if the seed crystal diameter is qualified, welding is started, and then the power is reduced to achieve cooling;

[0036] Set the set diameter 1 of the seed crystal in advance. When the seed crystal diameter is ≥ the set diameter 1, the seed crystal diameter is qualified. When the seed crystal diameter is < the set diameter 1, the seed crystal diameter is unqualified.

[0037] Set the set diameter 2 of the seed crystal in advance. If the seed crystal diameter is qualified, after the welding starts, when the seed crystal diameter reaches the set diameter 2, the power starts to be reduced to achieve cooling. The set diameter 2 = set diameter 1-0.5mm, that is, the set diameter 1 shrinks by 0.5mm to reach the set diameter 2;

[0038] The lowest seed crystal position 1 is set in advance. In step S2, when the seed crystal is inserted to the lowest seed crystal position 1 for the first time, if the seed crystal has not yet contacted the liquid surface, the insertion is stopped and an alarm is issued for manual intervention to avoid the graphite chuck and the weight being inserted below the liquid surface due to continued insertion, and to avoid the seed crystal being inserted too much and the CCD not being able to observe the seed crystal due to the visual angle, thus affecting the visual judgment. The lowest seed crystal position 1 is the lowest position of the seed crystal that ensures that the welding point can be completely seen on the CCD;

[0039] The lowest seed crystal position 2 is set in advance. In step S4, when the seed crystal is inserted to the lowest seed crystal position 2 for the fourth time, if the seed crystal diameter is still unqualified, the seed crystal stops being inserted and an alarm is given. The lowest seed crystal position 2 is 50 mm above the lower limit of the seed crystal. The lower limit of the seed crystal refers to the seed crystal position when the lower edge of the graphite chuck is flush with the lower edge of the guide tube after the furnace cover is unscrewed and the guide tube is lowered to the lower limit.

[0040] The contact voltage of the single crystal furnace is used to determine whether the seed crystal contacts the liquid surface. An electrode is arranged above the seed crystal, and the seed crystal is connected to a tungsten wire rope, which is electrically connected to the electrode to achieve electrical connection between the electrode and the seed crystal. That is to say, if the seed crystal does not contact the melt, the electrode voltage will remain at a stable value. When the seed crystal contacts the melt, the electrode voltage will suddenly change due to the conductivity of the melt. By monitoring this change, it can be determined whether the seed crystal has successfully contacted the melt.

[0041] The above embodiments are only preferred embodiments of the present invention and are not limitations of the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

Claims

1. An automatic welding method, characterized in that: The steps include: S1. Visually identify the seed crystal to determine whether the seed crystal is a new seed crystal or an old seed crystal; S2. After the seed crystal is inserted into the liquid surface for the first time, it is inserted into the liquid surface for the second time; S3. Perform the first seed crystal diameter test. If the seed crystal diameter fails, the seed crystal is inserted for the third time; S4. Perform a second seed crystal diameter test. If the seed crystal diameter fails to meet the requirements, the seed crystal is inserted for the fourth time. Wherein, in step S2, the new seed crystal is directly inserted down until it contacts the liquid surface, and the old seed crystal is first inserted down to the last fusion position, and then inserted down again until it contacts the liquid surface; During the first seed crystal diameter detection in step S3, the second seed crystal diameter detection in step S4, and the fourth seed crystal insertion process, if the seed crystal diameter is qualified, welding is started, and then the power is reduced to achieve cooling; An electrode electrically connected to the seed crystal is provided, and the electrode voltage is monitored to determine whether the seed crystal is in contact with the melt.

2. The automatic welding method according to claim 1, characterized in that: In step S1, the new seed crystal and the old seed crystal are judged by identifying or detecting the shape and surface smoothness of the seed crystal. The old seed crystal has fine crystals and necking left after the last seeding. The old seed crystal has conical residues at the bottom and its surface smoothness is low.

3. The automatic welding method according to claim 1, characterized in that: Set the set diameter 1 of the seed crystal in advance. When the seed crystal diameter is ≥ the set diameter 1, the seed crystal diameter is qualified. When the seed crystal diameter is < the set diameter 1, the seed crystal diameter is unqualified.

4. The automatic welding method according to claim 3, characterized in that: Set the set diameter 2 of the seed crystal in advance. When the seed crystal diameter is qualified, after the welding starts, when the seed crystal diameter reaches the set diameter 2, start to reduce the power to achieve cooling. The set diameter 1 shrinks by 0.5mm and then reaches the set diameter 2.

5. The automatic welding method according to claim 1, characterized in that: The lowest seed crystal position 1 is set in advance. In step S2, when the seed crystal is inserted to the lowest seed crystal position 1 for the first time, if the seed crystal has not yet contacted the liquid surface, the insertion is stopped and an alarm is issued for manual intervention.

6. The automatic welding method according to claim 1, characterized in that: The lowest seed crystal position 2 is set in advance. In step S4, when the seed crystal is inserted to the lowest seed crystal position 2 for the fourth time, if the seed crystal diameter is still unqualified, the seed crystal stops being inserted and an alarm is issued.

7. The automatic welding method according to claim 1, characterized in that: When monitoring the electrode voltage, when the electrode voltage is a stable value, the seed crystal is not in contact with the melt; when the electrode voltage changes suddenly, the seed crystal is in contact with the melt.

8. The automatic welding method according to claim 1, characterized in that: The seed crystal is connected to a tungsten wire rope, and the electrode is electrically connected to the tungsten wire rope.

9. The automatic welding method according to claim 1, characterized in that: In step S2, the second insertion is 3 mm.

10. The automatic welding method according to claim 1, characterized in that: In step S3, the third insertion is performed by inserting 3 mm.

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