The so-called vacuum packaging machines are all cavity structures, consisting of an upper vacuum chamber, a lower vacuum chamber and a sealing ring placed between the upper and lower vacuum chambers. Generally, the upper and lower vacuum chambers are made of cast-rolled aluminum alloy or stainless steel sheets after folding or die welding, and some of them are made of aluminum alloy and stainless steel respectively. There are two kinds of aluminum alloys: ordinary alloys and aluminum-magnesium alloys. The latter is acid and alkali resistant and corrosion resistant, but the cost is high. After milling aluminum alloy vacuum chamber, the sealing plane and sealing groove plane are very flat, and the sealing performance of vacuum chamber is good. The thickness of stainless steel plate is usually 2-4MM, which is easy to deform after vacuum compression, leading to weld cracking and vacuum chamber leakage. In addition, the sealing groove is generally formed on the peripheral plane of the vacuum chamber on stainless steel, which is affected by the processing technology, so the flatness of the sealing groove is poor and the sealing performance of the vacuum chamber is correspondingly reduced. Therefore, in some models, the upper vacuum chamber adopts aluminum alloy casting and rolling to process the sealing groove, and the lower vacuum chamber adopts thick stainless steel plate to process it into a flat plate, taking its advantages and making up its disadvantages.

Upper vacuum chamber opening, displacement and balancing device

There are two kinds of vacuum packaging machines in common use: single chamber and double chamber. The single chamber is a flap, and there are two groups of brackets at the back of the upper and lower vacuum chambers, with a long shaft with double torsion springs in the middle. The acting force is balanced by double torsion springs, and the opening angle varies from 45 degrees to 75 degrees. The double chamber reciprocates, and the lower vacuum chamber is divided into two working chambers, left and right. The upper vacuum chamber is supported by four connecting rods which are fixed on two long shafts. The long shaft is equipped with a tension spring fork, the lower parts of the two tension springs are located on the frame, and the upper parts are located on the tension spring fork, which plays a role in balancing the operating gravity. The two long shafts are positioned by two groups of bearing seats, and the upper parts of the four connecting rods are also embedded with miniature bearings, so that the left and right displacement is very easy, and a little pressure is applied when vacuum is started. The four connecting rods supporting the displaced upper vacuum chamber, the front and rear two on each long axis, must be kept parallel, and the left and right two groups of connecting rods must also be kept relatively parallel, so as to ensure that the upper vacuum chamber is kept parallel to the lower vacuum chamber at any position on the left and right, otherwise the upper vacuum chamber and the lower vacuum chamber cannot be kept parallel, and the operating pressure is obviously increased, and even the vacuum cannot be established normally in severe cases.

Hot-pressing sealing device and printing device

The device is installed in a vacuum chamber and usually has two groups and one group. Generally, the movable part of single-chamber flap is installed in the lower vacuum chamber, while the movable part of double-chamber reciprocating is installed in the upper vacuum chamber. The movable part device is mainly composed of the following parts: the heat sealing air chamber frame is fixed in the upper vacuum chamber, and the two ends are provided with guide posts and springs to form a reset device; the two ends of the hot pressing frame seat are provided with guide sleeves which are sleeved on the guide posts. There is a heat sealing air chamber between the heat sealing air chamber frame and the hot pressing frame seat (also called vacuum chamber as atmospheric chamber and small air chamber). The heat-sealed air chamber is made of plastic water pipes, both ends of which are clamped by clips, and rubber water is stuck on the inner tube of a bicycle or rickshaw. There is an air nozzle in the middle, a hot pressing frame made of epoxy board is fixed on the hot pressing frame seat, and winding shafts are arranged at both ends. Nickel-chromium alloy belt is tightly wound and positioned by winding shaft, and coated with heat-sealed lacquer cloth. The fixing device mainly consists of a printed rubber strip frame and a printed rubber strip. The printing rubber strip is made of heat-resistant silicone rubber, one side of which is twill or straight, and the other side is round or square hole. Circular or square characters made of silicone rubber are embedded in it, and the date of production is printed with concave and convex transparency at the same time. If you need color printing, you need a ribbon printer.

Vacuum pump, vacuum gauge and vacuum solenoid valve

There are two installation methods of vacuum pump. One is built-in, which usually adopts XD-020 and XD-040 single-stage rotary vane vacuum pumps. Generally, XD-020 pump is used for 400 packaging machines, and XD-040 pump is used for 500 packaging machines. Some manufacturers use two XD-020 pumps instead of one XD-040 pump to reduce costs, but the XD-020 pump is 2880 rpm. The other is external, usually using 2X- 15 two-stage rotary vane vacuum pump. This kind of pump has higher pumping speed and higher vacuum degree than single-stage pump, and is generally suitable for large-scale production with high vacuum degree, or it is required to be installed outdoors to reduce exhaust pollution.

The vacuum gauge is usually installed on the operation panel or the front of the fuselage has an axial front, and the gauge ￠60 is commonly used, with an accuracy of 2.5; 100 table with accuracy of 1.5.

Generally, there are two vacuum solenoid valves, one of which is ￠5 two-position three-way solenoid valve, which is mainly used to control the up-and-down displacement of hot-pressing sealing device. The other is a two-position two-way solenoid valve (15), which is mainly used to open the channel after vacuum heat sealing, so that the atmosphere can return to the vacuum chamber, otherwise the vacuum chamber cannot be opened.

Time relay, transformer and AC contactor

There are usually two time relays, one for controlling the vacuum time, usually 30S or 60S；; The other is to control the heat sealing time, which is generally 5S or 6 s, and there are three common types. One is JS 14A-y external, the machine body is installed on the electrical circuit board, and the adjusting knob is installed on the operation panel; The other is a turntable, the main body is installed on the operation panel, and there is a large turntable on the main body; There is also a digital display installed on the operation panel, with a vacuum degree of 0-99S and a heat seal of 0-9.9s.. ..

Usually two transformers are used. The smaller one is the control transformer, with an input of 380V, an output of 220V for the control loop and an output of 6.3V for the indicator light. The larger ones are heat-sealing transformers, generally 400W for 400-type packaging machines and 600W for 500-type packaging machines, with an input of 380V (220V for a small number of single-phase power packaging machines) and an output of 20-36V in five stages, with the minimum heat-sealing current of 20V in the first stage and the maximum heat-sealing current of 36V in the fifth stage. There are usually two AC contactors, one controls the vacuum pump and the other controls the heat sealing transformer. The general working voltage is 220V and the working current is 10A.

Because the working voltage of the control loop is 220 V, the working voltage of time relay, vacuum solenoid valve, AC contactor, counter and other coils is 220 V. ..