2. If the power of the three-phase motor is below kW, any two of the three terminals connected to the three-phase power supply can be connected to the single-phase power supply, and the other terminal is connected to any two terminals after a capacitor is connected in series. (Changing the access terminal means changing the direction) The capacitance is 10uf.
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Introduction of sewing machine
The development of sewing machines.
Sewing machine is a machine that uses one or more sewing threads to form one or more stitches on sewing materials, so that one or more layers of sewing materials are interwoven or sewn together.
The sewing machine can sew cotton, linen, silk, wool, man-made fiber and other fabrics and leather, plastic, paper and other products. The sewing stitch is neat, beautiful, flat and firm, with fast sewing speed and simple use. From it, hand embroidery, computer embroidery and other art forms are derived.
After the world sewing machine industry moved from Europe and America to Japan, South Korea, Taiwan Province Province and Singapore, it began to move to China in the early 1990s. At the beginning of the 20th century, more than 70% of the world sewing machine production was in China. However, 70%-90% of domestic high-end
The machine market was occupied by Japanese and German enterprises. As for low-end sewing machine products, the world sewing machine industry has completed the transfer to China, and the industrial transfer has gradually extended to high-end products. With the increasing competition in sewing machinery manufacturing industry, sewing machinery manufacturing industry has become large-scale.
Mergers and acquisitions and capital operation between enterprises are becoming more and more frequent, and domestic excellent sewing machinery manufacturing enterprises pay more and more attention to the research of industry market, especially the in-depth study of industry development environment and product buyers. Because of this, a large number of domestic excellent sewing machinery brands have risen rapidly and gradually become the leader in the sewing machinery manufacturing industry!
1869, Li Hongzhang, a representative of the Westernization School, visited Britain and brought a gold-plated sewing machine as a gift to Empress Dowager Cixi when he returned home. At that time, the British media also reported this matter.
The earliest information that sewing machines can be found in China market today is advertisements. 1872 12 14, Shen Bao published a notice of "clothing machines for sale" in Jinlong foreign firm. The notice said, "The sewing machines newly arrived in foreign countries cost fifty taels each. Please contact us if you want to buy. " At that time, this foreign firm distributed the products of American Shengjia Company (then called Singer Company).
Wang Tao, a famous thinker and political commentator in modern times, once described this machine like this. At that time, his neighbor was an American and had a sewing machine at home. In 1875, Wang Tao wrote: "There is a peculiar sewing machine in the west, which uses a wonderful needle and excels in craftsmanship. There is a copper plate with wings on it, and the iron wheel kick plate is placed under the needle. The wheel rotates, holding a palm, and the fine needle is dense and long in an instant. "
1880 or so, Shengjia Company established Shanghai Feng Company on Nanjing Road (now No.446 Nanjing East Road) in Shanghai. In order to promote products, the company hired female workers from China with high salaries. After training, they were asked to bring sewing machines to perform along the street and introduce the operation methods of sewing machines to the public. Soon Shengjia sewing machine became a well-known advanced clothing machinery in Shanghai.
For a long time, Shengjia has almost become synonymous with sewing machines, and it is also one of the western industrial products that entered China earlier. In China, the earliest sewing machines were called "iron car", "foreign machine" and "needle car". The last emperor Puyi once gave empress Wanrong a sewing machine, so it was still a rarity in China at that time.
1905, Shanghai first started to manufacture spare parts for sewing machines and set up some small workshops to produce spare parts.
1928, Shanghai xiechang sewing machine factory produced the first 44- 13 industrial sewing machine. In the same year, Shanghai Mei Sheng Sewing Machine Factory also produced the first household sewing machine.
Before 1949, the output of sewing machines in old China was very low, with an annual output of less than 4,000 sets. At that time, the sewing equipment market was mainly monopolized by American Shengjia Company.
From 65438 to 0949, after the founding of New China, the sewing machinery industry was fully developed. The industry has gone through the stages of reorganization, public-private partnership, merger and cooperation, etc., and has carried out a reasonable division of labor, forming a number of key enterprises, such as SAIC, Changzhou, Feiren and Butterfly.
Sewing machine manufacturers such as Tianjin Sewing Machine Factory and Guangzhou South China Sewing Machine Factory mainly produce ordinary household sewing machines and low-grade industrial sewing machines.
At the end of 1950s, light industry popularized and standardized household sewing machines, unified design drawings and improved the compatibility of parts, which led to more and more sewing machine manufacturers, and developed sunflower fans, medical surgery, badminton, bicycle tires and.
Special purpose sewing machines such as cord fabric splicing. According to statistics, as of 1980, there are 56 sewing machine manufacturers in 22 provinces and cities across the country. As of 1982, the output of sewing machines in China reached12.86 million, ranking first in the world.
In the mid-1980s, with the constant adjustment of the market and consumption structure, the product structure of sewing equipment developed to high speed and serialization on the basis of medium and low speed industrial sewing machines, and electronic and computer technologies were also widely used in sewing machines. Meanwhile, China
It also completed the establishment of parts supporting system and built a huge sewing machine sales network. Some sewing machine enterprises digest and absorb advanced technology after introducing foreign advanced technology.
In the early 1990s, internationally renowned enterprises entered China and set up joint ventures and wholly-owned enterprises in China.
In the late 1990s, private enterprises began to rise, and the great adjustment of industrial structure promoted the great development of the industry, forming six major producing areas and bases in Shanghai, Jiangsu, Zhejiang, Shaanxi, Tianjin and Guangzhou.
By the end of 2004, there were more than 600 sewing machine manufacturers and more than 0/000 spare parts manufacturers in China, with an annual output of140.08 million sets and a total output value of about 28 billion yuan, with nearly 1000 varieties, and it has become one of the major sewing machine manufacturers in the world.
According to the use, sewing machines can be divided into household sewing machines, industrial sewing machines and service sewing machines located between them. According to the driving mode, it can be divided into manual sewing machine, pedal sewing machine and electric sewing machine. According to the stitch, it can be divided into hand stitch and lock stitch.
Sewing machine, single-thread chain stitch, double-thread or multi-thread chain stitch, single-thread or multi-thread chain stitch, multi-thread chain stitch.
2. Types of sewing machines
household sewing machines
In the early days, it was basically a single-needle manual sewing machine, and later, an electric sewing machine was invented, which has always become the mainstream of the market. According to its mechanism and suture form, it can be roughly divided into JA type, JB type, JG type and JH type. The picture below shows a household sewing machine-JG household electronic multifunctional sewing machine.
Industrial sewing machine
Most industrial sewing machines belong to general sewing machines, including flat sewing machine, chain sewing machine, quilting machine, sewing machine and flat sewing machine, among which flat sewing machine has the highest utilization rate.
Step 3: ingredients
General sewing machine consists of four parts: head, frame, transmission and accessories.
The nose is the main part of sewing machine. It consists of four mechanisms: piercing, hooking, picking and feeding, and auxiliary mechanisms such as winding, pressing and tooth dropping. All mechanisms work in a reasonable and coordinated way, working in cycles, and sewing materials.
The frame is divided into two forms: bed board and chassis. The bed plate of the bed plate frame plays the role of supporting the machine head and is used as a workbench during sewing operation. There are many styles of bed boards, including one or more bucket folding, cabinet type, desktop type and so on. The chassis of the chassis frame plays the role of supporting and storing the machine head, which makes the sewing machine easy to carry and keep.
The transmission part of sewing machine consists of frame, hand crank or motor. The frame is the pillar of the machine, supporting the base and pedals. When in use, the operator steps on the pedal to drive the pulley to rotate through the crank, and then drives the machine head to rotate through the belt. Most hand cranks or motors are directly mounted on the nose.
Accessories of sewing machine include needles, spools, screwdrivers, oil pots, etc.
4, machine classification
There are many ways to classify sewing machines, and the common one is to distinguish them by stitch and use. The stitch of sewing machine can be divided into lock stitch and chain stitch. Lock stitch is the most common stitch, which consists of two stitches, intertwined like a rope, and its interweaving point is in the middle of sewing materials. From the cross section of the stitch, two stitches are like two locks, so it is called a lock stitch. This kind of needle is used to shrink.
Small sewing materials, such as cotton, wool or leather, have the same front and back shapes, such as the same dotted line. The stitch distribution is dense, and the sewing fastness is generally higher than that of manual sewing.
Chain stitch is formed by self-connection or mutual connection of stitches, and commonly used are single-line chain stitch, double-line chain stitch and three-line wrapped stitch. This stitch is characterized by elasticity, which can expand and contract with the sewing material without breaking the sewing thread. It is suitable for garments made of linear elastic fabrics or products and garment grey cloth that is easy to loosen.
In addition, sewing machines can be divided into household, industrial and service machines according to their uses, and can also be divided into manual sewing machines, pedal sewing machines and electric sewing machines according to their driving forms.
Suture principle
Just like cars, the basic principles of most sewing machines are the same. The core of automobile is internal combustion engine, and the core of sewing machine is coil sewing system.
The sewing method of coil is very different from ordinary manual sewing. In the simplest hand sewing, the sewing worker ties a thread at the small eye of the needle end, and then passes the needle and thread completely through two pieces of cloth, from one side to the other and back to the original side. In this way, the needle drives the thread in and out of the fabric and sews them together.
Although it is simple to pull by hand, it is extremely difficult to pull by machine. The machine needs to release the needle on one side of the fabric and then immediately grab the needle again on the other side. Then, it needs to pull all loose threads out of the fabric, turn the direction of the needle, and then reverse it.
Repeat all steps through. This process is too complicated and impractical for simple machines, and even for manual work, it is only useful when using short lines.
On the contrary, the sewing machine only needs to pass the needle part through the fabric. On the machine needle, the eye of the needle is just behind the needle tip, not at the end of the needle.
The needle is fixed on the needle bar and pulled up and down by a motor through a series of gears and cams (which will be described in detail later).
When the needle tip passes through the fabric, it pulls a small coil from one side to the other. A device under the fabric will grab this coil and then wrap it around another thread or another coil of the same thread. In the next two sections, we will see how this system works.
The simplest stitch is chain stitch. To sew chain stitches, the sewing machine will loop the same length of thread behind the thread. The fabric is placed on the metal plate under the needle and fixed with the presser foot. At the beginning of each sewing, the needle will pull a loop on the fabric. One person did it.
The device of the coil grasps the coil before the needle is pulled out, and the device moves synchronously with the needle. Once the needle is pulled out of the fabric, the cloth feeding device (described later) will pull the fabric forward.
When the needle passes through the fabric again, the new loop will pass directly through the middle of the previous loop. The equipment that makes the coil will grab the wire again and make a coil around the next coil. In this way, each coil will fix the next coil.
The main advantage of chain sewing is its fast sewing speed. However, it is not particularly strong. If one end of the thread is loose, the whole sewing may be loose. Most sewing machines use a stronger stitch called lock stitch. You can understand the working principle of a typical sewing device in the following animation.
The most important parts of sewing equipment are swing hook and spool assembly. A bobbin is a winding wire placed under a fabric. It is located in the center of the shuttle, which is driven by a motor and rotates synchronously with the movement of the needle.
Like chain sewing, the needle pulls out a loop through the fabric, and the cloth feeder moves the fabric forward, and it rises again and then puts in another loop. However, this sewing mechanism does not connect different coils together, but connects them with another wire that is loosened from the spool.
When the needle puts the thread into the coil, the rotating shuttle grabs the coil with a crochet. When the shuttle rotates, it pulls the coil off the spool. This makes the suture very strong.
This rotating shuttle is also evolved from the straight shuttle.
The sewing principle of sewing machine has developed from straight shuttle to rotary shuttle, which has entered a mature stage.