A kind of vacuum die-casting mould vacuum detecting method
Technical field
the present invention relates to vacuum die-casting mould production testing technical field, particularly a kind of vacuum die-casting mould vacuum detecting method.
Background technology
in evacuated die-casting process production run, die casting, after closing and before being filled with molten metal bath, carries out vacuum exhaust in mold cavity, reduces volume gas and the die casting gas content of injection mo(u)lding and pressure maintaining period, thus reduces gas hole defect, lifting casting quality.Vacuum die-casting mould need after vacuumizing end, when carrying out die cast during this period of time in, the vacuum tightness in mold cavity reaches below a certain numerical value, and the vacuum tightness namely in mold cavity is relevant with the sealing property of mould.Vacuum die-casting mould in the past after finalization of the manufacture, just to can learn whether the sealing property of mould reaches requirement when test-manufacturing and going into operation, namely whether its leakage rate meets the requirements, and again detects and revises, reduce work production efficiency for the vacuum die-casting mould Xu Fan factory not reaching requirement.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of vacuum die-casting mould vacuum detecting method for detecting mold cavity slip.
For solving the problems of the technologies described above adopted technical scheme: a kind of vacuum die-casting mould vacuum detecting method, comprises the following steps: to be vacuumized mold cavity by vacuum pump and obtain the suction performance of vacuum pump; By the air pressure in air pressure detecting sensor Real-time Obtaining mold cavity; Draw the slip of mold cavity according to formulae discovery, described formula: T=V/S* ㏑ (P2/P1), wherein, T is the pumpdown time, and S is the suction performance of vacuum pump, and P2 is initial gas pressure, and P1 is target air pressure, and V is volume.
Further, utilize vacuum pump to vacuumize mold cavity and reach minimum value, close vacuum pump, by the air pressure change in air pressure detecting sensor observation mold cavity, describe air pressure and the relation curve of time, extract wherein fragment and substitute into above-mentioned formulae discovery, the S drawn is the slip of mold cavity.
Further, vacuum pump is utilized to vacuumize mold cavity, the suction performance of record vacuum pump, simultaneously by the air pressure change in air pressure detecting sensor observation mold cavity, describe air pressure and the relation curve of time, extract wherein fragment and substitute into above-mentioned formulae discovery, the S drawn is true suction performance, now suction performance-true the suction performance of the slip=vacuum pump of mold cavity.
Further, vacuum pump is utilized to vacuumize mold cavity and by the air pressure in air pressure detecting sensor real-time monitored mold cavity, regulate the suction performance of vacuum pump to make stable gas pressure in mold cavity a definite value, now the slip of mold cavity is the suction performance of this vacuum pump.
Beneficial effect: this vacuum die-casting mould vacuum detecting method is by carrying out the vacuum pumping of simulated field to mold cavity, and the air pressure change recorded wherein and the curve of time, the leakage rate of mold cavity is gone out by theory calculate, thus mould sealing condition can be assessed whether reach production requirement before putting into production, the Hou Caifan factory that avoids putting into production again detects and revises, and effectively improves production work efficiency.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the present invention is described further;
Fig. 1 is overhaul flow chart schematic diagram of the present invention;
Fig. 2 is the schematic diagram vacuumized mold cavity by vacuum pump in invention.
Embodiment
The present invention mainly carries out the vacuum pumping of simulated field to mould by use vacuum pump, and the air pressure change recorded wherein and the relation curve of time, by calculating the slip of mold cavity, and then show whether the sealing property of mould meets production requirement.
The vacuum pumping of simulated field has two links, namely injection punch head reach advances at a slow speed the low-speed stage of molten metal and molten metal to inject high speed stage in mold cavity through ingate, can only carry out at low-speed stage the vacuum pumping of mold cavity in actual production, after vacuum pumping terminates to molten metal be full of mold cavity during this period of time in, need to keep the vacuum tightness in mold cavity to reach below a certain numerical value, high speed stage is entered after low-speed stage terminates, and the leakage stage of namely mould during this period of time, because the time of high speed stage generally only has about 0.05 second, namely mould can be considered certain value in the slip in the stage of leakage.
As depicted in figs. 1 and 2, this slip is tried to achieve by following detection method, and a kind of vacuum die-casting mould vacuum detecting method of the present invention, comprises the following steps: vacuumized by vacuum pump 1 pair of mold cavity 2 and obtained the suction performance of vacuum pump 1; By the air pressure in air pressure detecting sensor 3 Real-time Obtaining mold cavity 2; Draw the slip of mold cavity 2 according to formulae discovery, described formula: T=V/S* ㏑ (P2/P1), wherein, T is the pumpdown time, and S is the suction performance of vacuum pump, and P2 is initial gas pressure, and P1 is target air pressure, and V is volume.
Wherein, utilize vacuum pump 1 pair of mold cavity 2 to vacuumize and reach minimum value, close vacuum pump 1, the air pressure change in mold cavity 2 is observed by air pressure detecting sensor 3, describe air pressure and the relation curve of time, extract wherein fragment and substitute into above-mentioned formulae discovery, the S drawn is the slip of mold cavity 2.
Formula T=V/S* ㏑ (P2/P1) is the vacuum rate computing formula that a vacuum pump vacuumizes sealed chamber, conversely, first can vacuumize mold cavity 2 and reach minimum value, also be substantially be in perfect vacuum state in mold cavity 2, because mold cavity 2 has not been hermetic, exist and leak, therefore utilize above-mentioned formula to carry out calculating S conversely, now S is the slip of mold cavity.
Certainly, vacuum pump 1 pair of mold cavity 2 can also be utilized to carry out simulation vacuumize, the suction performance of record vacuum pump 1, observed the air pressure change in mold cavity by air pressure detecting sensor 3 simultaneously, describe air pressure and the relation curve of time, extract wherein fragment and substitute into above-mentioned formulae discovery, the S drawn is true suction performance, now suction performance-true the suction performance of the slip=vacuum pump of mold cavity 2.When carrying out simulation and vacuumizing, because mold cavity 2 exists to leak, the S gone out according to formulae discovery is not the suction performance of aspiration pump, but a true suction performance, and the suction performance of vacuum pump 1 directly can be observed and drawing, thus the suction performance of the slip=vacuum pump of mold cavity 2-truly bleed.
In addition, because the slip of mold cavity 2 can become large because the draught head in die cavity and between the atmospheric pressure in the external world increases, therefore, when utilize in vacuum pump 1 pair of mold cavity 2 carry out simulation vacuumize time, regulate the suction performance of vacuum pump 1, and observe the atmospheric pressure value in mold cavity 2, when the stable gas pressure in tool mold cavity 2 is a definite value, slip now in mold cavity 2 and the suction performance of vacuum pump 1 reach balance, and the slip of mold cavity 2 is the suction performance regulating final vacuum pump 1.
By reference to the accompanying drawings embodiments of the present invention are explained in detail above, but the invention is not restricted to above-mentioned embodiment, in the ken that described technical field those of ordinary skill possesses, various change can also be made under the prerequisite not departing from present inventive concept.