CN101569925B - Gating design method for die-casting formation of large thin-wall element with narrow flange - Google Patents

Abstract

The invention provides a gating design method for die-casting formation of a large thin-wall element with narrow flange. The method comprises the following steps: step 10, calculating the section areaof a mater gate, and dividing the section area value to each gate so as to obtain the section area of each gate; step 20, calculating the width of each gate; step 30, calculating cycloid base radiuse s of non-edge gate outlines according to the gate widths so as to obtain the cycloid equation of each non-edge gate outline; step 40, calculating cycloid base radiuses of two-edge gate outlines according to the gate widths so as to obtain the cycloid equation of the two-edge gate outlines; and step 50, designing the gate cross dimensions according to the section areas of the gates and the outline sizes. The method changes the conventional straight-line-form gate into a continuous curve form without point of discontinuity, takes advantage of the isochronism of the cycloid to reduce the flowing power loss of a fused mass, causes die-casting fronts to simultaneously reach a destination, and effectively reduces the die-casting defects.

Description

The cast gate method for designing that has the large thin-wall element die cast of strait flange

[technical field]

The present invention relates to the method for designing of running channel in a kind of die cast mould, particularly a kind of two-way tangent cycloid cast gate method for designing towards the large thin-wall element die cast that has strait flange.

[background technology]

Large-sized thin-wall die casting particularly large thin-wall casing class die casting is the strength member of occasions such as a class is used to carry, rotates, illumination, and for example electric slicer gear-box, air-cooled DID engine body, light-alloy inlet manifold etc. all belong to this type of part.The full-size of the type die casting can reach more than the 400mm, and thickness can be to 1.5mm or littler, and die cast mould full-size often reaches more than the 800mm.

Large thin-wall casing class die casting have complex structure, required precision performance requirement higher, that bear alternate load higher, to surface requirements such as wearability and surface compact degree than characteristics such as height.

The quality of die cast mould is to produce the key of qualified large thin-wall casing class die casting.But this mould design and manufacturing all have very big difficulty.The problem that exists comprises: wall thickness crosses thin or defectives such as inhomogeneous easy generation current mark, corner incompleteness or crackle, cold shut, slag inclusion, and is poor by the constant product quality that the mould of conventional method design is produced, and is difficult to satisfy the correlation technique requirement.

In the design of die cast mould, Design of Runner System is ten minutes the key link.The box parts that has flange mostly is the outward appearance part, does not allow cast gate to be opened in outer surface.Abide by the basic principle of cast gate design, should be opened in the flange place, the immediate problem that brings like this is exactly that the melt flows filling process is affected.When pressurized melt flows, through directly impacting on the mold cavity sidewall vertical behind the narrower flange with flow direction, cross cavity lateral after, pressure and speed is significantly decay, and then fills the other parts of die cavity.Like this, cold shut will occur in the forward position of melt, short, defectives such as crackle, pore, and cause percent defective to rise.

Therefore, improve the structure of running gate system, will take method to solve because the problem that the existence of flange causes melt pressure and speed significantly to decay, simultaneously, reduce the structure of cast gate in the extrusion process design, mobile bring pressure and power loss thereby the minimizing melt is obstructed.

[summary of the invention]

The technical problem to be solved in the present invention, be to provide a kind of cast gate method for designing that has the large thin-wall element die cast of strait flange, the cast gate of conventional form of straight lines is changed into the full curve form of no catastrophe point, utilize the isochronism matter of cycloid, reduce the mobile power attenuation of melt, make the die casting forward arrive at terminal point simultaneously, effectively reduce the die casting defective.

One of the object of the invention is achieved in that a kind of cast gate method for designing that has the large thin-wall element die cast of strait flange, comprises the steps:

Step 10, calculate total gate area, and decompose each cast gate, draw each gate area;

Step 20, calculate each cast gate width;

Step 30, calculate the cycloid base radius of non-side gate profile, thereby draw the cycloid equation of each non-side gate profile according to the cast gate width;

Step 40, calculate the cycloid base radius of both sides cast gate profile, thereby draw the cycloid equation of two side gate profiles according to the cast gate width;

Step 50, according to gate area and overall size design cast gate cross dimensions.

Wherein, in the described step 30, the base radius r of the left side cycloid profile of i non-side gate _I1And the base radius r of right side cycloid profile _I2Be respectively:

$r_{i1}=\frac{w}{w_{i-1}+w_i}\·w_i$ $r_{i2}=\frac{w_i}{w_i+w_{i+1}}\·w_{i+1}$

In the formula: w _I-1Be the width of i-1 non-side gate,

w _iBe the width of i non-side gate,

w _I+1It is the width of i+1 non-side gate;

The cycloid equation of the left side cycloid profile of the i of gained non-side gate and the cycloid equation of right side cycloid profile are respectively thus:

$\left\{\begin{array}{c}x=r_{i1}t-r_{i1}\sin t\\ y=r_{i1}-r_{i1}\cos t\end{array}\right.$ $\left\{\begin{array}{c}x=r_{i2}t-r_{i2}\sin t\\ y=r_{i2}-r_{i2}\cos t\end{array}\right.$

In the formula: t is the filling time of die cavity.

Wherein, in the described step 40, the base radius r of the right side cycloid profile of the 1st side gate ₁₂And the 2nd base radius r that side gate is the left side cycloid profile of n cast gate _N1Be respectively:

r ₁₂＝w ₁/2 r _n1＝w _n/2

In the formula: w ₁Be the width of the 1st side gate,

W _nIt is the width of the 2nd side gate;

The cycloid equation of the cycloid equation of the right side cycloid profile of the 1st of gained the side gate and the 2nd side gate left side cycloid profile is respectively thus:

$\left\{\begin{array}{c}x=r_{12}t-r_{12}\sin t\\ y=r_{12}-r_{12}\cos t\end{array}\right.$ $\left\{\begin{array}{c}x=r_{n1}t-r_{n1}\sin t\\ y=r_{n1}-r_{n1}\cos t\end{array}\right.$

In the formula: t is the filling time of die cavity.

Technique scheme also further comprises step 60: design cycloid shape import running channel and this straight wall in the Zhi Bi position of large thin-wall element are tangent, and this base radius of this cycloid is the twice of large thin-wall element flange width.

Wherein, the import of cycloid shape described in the step 60 running channel adopts the built-up type structure to process.

Total gate area is to calculate according to formula A=m/ ρ vt in the above-mentioned steps 10, the method that total gate area is decomposed each cast gate is to be increased progressively successively to the centre by two ends according to total cast gate number, and increasing progressively on the adjacent linear size is no more than 15% rule and carries out.

The theory that the present invention utilizes melt to go out through the thin-walled orifice flow under the pressure difference effect has designed the tangent cycloid cast gate profile of novel dual-projection form, and derive its equation.Its essence is the full curve form of the cast gate of conventional form of straight lines being changed into no catastrophe point, utilize the isochronism matter of cycloid, reduce the mobile power attenuation of melt, effectively reduce the die casting defective, have following beneficial effect:

(1) cast gate of cycloid shape can make a plurality of molten streams arrive at the injection forward simultaneously, improved traditional wayward forward's time of advent and made inhomogeneous cooling, help melt and be full of die cavity, guarantee the size and dimension precision of die casting, thereby bring the problem of more die casting defective.

Connect with tangent half cycloid between (2) two cast gates, and two and half cycloids are smooth automatically continuously, make to be difficult for forming defectives such as pore, slag inclusion at the cast gate place, improved the quality of die casting.

(3) advance the cast gate side direction and also adopt the cycloid form, changed the direct situation that causes the huge pressure loss at the mold cavity sidewall vertical of impacting of pressurized melt traditionally with flow direction, help reducing technological requirement, thin-walled and flange are shaped simultaneously for the moulding of large-scale die casting spare.

[description of drawings]

The present invention is further illustrated in conjunction with the embodiments with reference to the accompanying drawings.

Fig. 1 is the schematic flow sheet of the inventive method.

Fig. 2 a and Fig. 2 b are respectively the structural representations of lampshade aluminum alloy die casting loam cake and lower cover in the embodiment of the invention one.

Fig. 3 is that the cast gate horizontal direction distributes and the structural representation think of in the inventive method.

Fig. 4 is the cycloid equation inference principle schematic of i the tangent cycloid of non-side gate profile in the inventive method.

Fig. 5 is the cycloid equation inference principle schematic of the tangent cycloid of first side gate profile in the inventive method.

Fig. 6 is the cycloid shape import running channel structural representation of Zhi Bi position in the inventive method.

[specific embodiment]

See also shown in Figure 1ly, the present invention has the cast gate method for designing of the large thin-wall element die cast of strait flange, comprises the steps:

Step 10, calculate total gate area, and decompose each cast gate, draw each gate area;

Step 20, calculate each cast gate width;

Step 30, calculate the cycloid base radius of non-side gate profile, thereby draw the cycloid equation of each non-side gate profile according to the cast gate width;

Step 40, calculate the cycloid base radius of both sides cast gate profile, thereby draw the cycloid equation of two side gate profiles according to the cast gate width;

Step 50, according to gate area and overall size design cast gate cross dimensions.

Step 60: design cycloid shape import running channel and this straight wall in the Zhi Bi position of large thin-wall element are tangent, and the base radius of this cycloid is the twice of large thin-wall element flange width.

Embodiment one

Shown in Fig. 2 a and 2b, this embodiment is an example with the lampshade aluminum alloy die casting of certain specification, and the Outside Dimensions of this die casting is 405mm * 385mm * 164mm, and average wall thickness is 2.0mm, thinnest part 1.5mm.Flange width H ₀=5mm, the density p=2.4g/cm of melt ³, by the quality of molten metal m=1580g of ingate, injection speed v=2500～3000cm/s, loading time t=0.014～0.020s.

Step 10, calculating ingate sectional area A:

A＝m/ρvt＝1580/(2.4×2500×0.020)＝13.16cm ²

As shown in Figure 3, set 8 cast gates, establish each cast gate A _iArea is respectively A ₁, A ₂..., A ₈, total gate area A is decomposed each cast gate, decomposition method is for to be increased progressively successively to the centre by two ends according to total cast gate number, and increasing progressively on the adjacent linear size be no more than 15%, draws each gate area:

A ₁＝1.5cm ²，A ₂＝1.5cm ²，A ₃＝1.7cm ²，A ₄＝1.9cm ²，A ₅＝1.9cm ²，A ₆＝1.7cm ²，A ₇＝1.5cm ²，A ₈＝1.5cm ²

Step 20, calculate each cast gate width:

Calculate each cast gate width by conventional method and be respectively w ₁=w ₂=w ₇=w ₈=12mm; w ₃=w ₆=14mm; w ₄=w ₅=16mm; Establish the spacing L of adjacent gate again ₁=L ₇=21mm, L ₂=L ₃=L ₆=L ₅=34mm, L ₄=99mm.

The cycloid base radius and the cycloid equation of step 30, the non-side gate profile of calculating:

(1) calculates base radius

As shown in Figure 4, the base radius r of the left side cycloid profile of i non-side gate _I1And the base radius r of right side cycloid profile _I2Be respectively:

$r_{i1}=\frac{w}{w_{i-1}+w_i}\·w_i$ $r_{i2}=\frac{w_i}{w_i+w_{i+1}}\·w_{i+1}$

In the formula: w _I-1Be the width of i-1 non-side gate,

w _iBe the width of i non-side gate,

w _I+1It is the width of i+1 non-side gate;

Concrete calculating can get: r ₂₁=r ₇₂=6mm, r ₂₂=r ₇₁=6.5mm, r ₃₁=r ₆₂=7.5mm, r ₃₂=r ₆₁=7.5mm, r ₄₁=r ₅₂=8.5mm, r ₄₂=r ₅₁=8mm.

(2) draw the cycloid equation

The equation of cycloid is:

$\left\{\begin{array}{c}x=r_{b}t-r_b\sin t\\ y=r_b-r_b\cos t\end{array}\right.$

In the formula: r _bBe the cycloid base radius, it changes along with the position of cast gate,

T is the filling time of die cavity;

Still referring to shown in Figure 4, be example with the left side cycloid profile of i non-side gate, it is with O _I-1Be separation, respectively get with r _I-1,2And r _I1For half period of the cycloid of base radius is spliced.

With the equation of i base radius substitution cycloid, can draw the cycloid equation of the left side cycloid profile of i non-side gate, in like manner can derive the cycloid equation of its right side cycloid profile, it is respectively:

$\left\{\begin{array}{c}x=r_{i1}t-r_{i1}\sin t\\ y=r_{i1}-r_{i1}\cos t\end{array}\right.$ $\left\{\begin{array}{c}x=r_{i2}t-r_{i2}\sin t\\ y=r_{i2}-r_{i2}\cos t\end{array}\right.$

With each base radius r ₂₁=r ₇₂=6mm, r ₂₂=r ₇₁=6.5mm, r ₃₁=r ₆₂=7.5mm, r ₃₂=r ₆₁=7.5mm, r ₄₁=r ₅₂=8.5mm, r ₄₂=r ₅₁=8mm substitution following formula can get the cycloid equation of 6 non-side gate both sides cycloid profiles, does not list one by one herein.

The cycloid base radius and the cycloid equation of step 40, calculating two side gate profiles;

Side gate is meant the cast gate at large thin-wall element edge, generally has two, is distributed in both sides, see also shown in Figure 5, the base radius r of the right side cycloid profile of the 1st side gate ₁₂For:

r ₁₂=w ₁/ 2=6mm (in the formula, w ₁Be the width of the 1st side gate)

In like manner can calculate the i.e. base radius r of the left side cycloid profile of the 8th cast gate of the 2nd side gate ₈₁For:

R ₈₁=w ₈/ 2=6mm (in the formula, w ₈Be the width of the 2nd side gate)

The cycloid equation of the left side cycloid profile of the cycloid equation of the right side cycloid profile of the 1st of gained the side gate and the 2nd side gate is respectively thus:

$\left\{\begin{array}{c}x=r_{12}t-r_{12}\sin t\\ y=r_{12}-r_{12}\cos t\end{array}\right.$ $\left\{\begin{array}{c}x=r_{81}t-r_{81}\sin t\\ y=r_{81}-r_{81}\cos t\end{array}\right.$

According to above-mentioned all cycloid equations, can draw out 14 cycloid profiles altogether, and intercepting half period curve.

Step 50, according to gate area and overall size design cast gate cross dimensions.

This step is carried out according to the computational methods of routine.The maximum ga(u)ge of cast gate is not more than half of continuous die casting wall thickness.Here get 0.85mm.Generally with the cast gate Section Design for falling trapezoidal faces, can calculate its width according to the area of ingate.Cast gate length is got 2～3mm.

Step 60: design cycloid shape import running channel and this straight wall in the Zhi Bi position of large thin-wall element are tangent:

As shown in Figure 6, at the Position Design cycloid shape import running channel 2 tangent with the straight wall of large thin-wall element 1, thereby guarantee that melt flows with the direction shown in the arrow in scheming, flange 3 parts then automatic overflow are filled, to overcome in the running channel of straight line import in the past, melt flows is directly impacted on the mold cavity sidewall vertical with flow direction after through narrower flange, cross cavity lateral after, pressure and speed is the shortcoming of decay significantly.

If flange 3 width are H ₀, the cycloid basic circle at import running channel 2 cast gate places is for getting r _b=2H ₀=10mm.

Substitution cycloid equation can be somebody's turn to do the import running channel cycloid equation with the tangent position of straight wall:

$\left\{\begin{array}{c}x=r_{b}t-r_b\mathrm{sint}=10t-10\mathrm{sint}\\ y=r_b-r_b\mathrm{cost}=10-10\mathrm{cost}\end{array}\right.$

Usually because of advancing to water a little not on die joint, can bring the cycloid running channel processing difficulties of curve shape,, be convenient to process so running channel can adopt the built-up type structure.

Claims (6)

1. cast gate method for designing that has the large thin-wall element die cast of strait flange comprises:

Step 10, calculate total gate area, and decompose each cast gate, draw each gate area;

Step 20, calculate each cast gate width;

It is characterized in that, also comprise the steps:

Step 30, calculate the cycloid base radius of non-side gate profile, thereby draw the cycloid equation of each non-side gate profile according to the cast gate width;

Step 40, calculate the cycloid base radius of both sides cast gate profile, thereby draw the cycloid equation of two side gate profiles according to the cast gate width;

Step 50, according to gate area and overall size design cast gate cross dimensions;

Step 60: design cycloid shape import running channel and this straight wall in the Zhi Bi position of large thin-wall element are tangent.

2. have the cast gate method for designing of the large thin-wall element die cast of strait flange according to claim 1, it is characterized in that: in the described step 30, the base radius r of the left side cycloid profile of i non-side gate _I1And the base radius r of right side cycloid profile _I2Be respectively:

$r_{i1}=\frac{w}{w_{i-1}+w_i}\·w_i$ $r_{i2}=\frac{w_i}{w_i+w_{i+1}}\·w_{i+1}$

In the formula: w is the width of total cast gate,

w _I-1Be the width of i-1 non-side gate,

w _iBe the width of i non-side gate,

w _I+1It is the width of i+1 non-side gate;

The cycloid equation of the left side cycloid profile of the i of gained non-side gate and the cycloid equation of right side cycloid profile are respectively thus:

$\left\{\begin{array}{c}x=r_{i1}t-r_{i1}\sin t\\ y=r_{i1}-r_{i1}\cos t\end{array}\right.$ $\left\{\begin{array}{c}x=r_{i2}t-r_{i2}\sin t\\ y=r_{i2}-r_{i2}\cos t\end{array}\right.$

In the formula: t is the filling time of die cavity.

3. have the cast gate method for designing of the large thin-wall element die cast of strait flange according to claim 1, it is characterized in that: in the described step 40, the base radius r of the right side cycloid profile of the 1st side gate ₁₂And the 2nd base radius r that side gate is the left side cycloid profile of n cast gate _N1Be respectively:

r ₁₂＝w ₁/2 r _n1＝w _n/2

In the formula: w ₁Be the width of the 1st side gate,

W _nIt is the width of the 2nd side gate;

The cycloid equation of the cycloid equation of the right side cycloid profile of the 1st of gained the side gate and the 2nd side gate left side cycloid profile is respectively thus:

$\left\{\begin{array}{c}x=r_{12}t-r_{12}\sin t\\ y=r_{12}-r_{12}\cos t\end{array}\right.$ $\left\{\begin{array}{c}x=r_{n1}t-r_{n1}\sin t\\ y=r_{n1}-r_{n1}\cos t\end{array}\right.$

In the formula: t is the filling time of die cavity, and n is a natural number.

4. have the cast gate method for designing of the large thin-wall element die cast of strait flange according to claim 1, it is characterized in that, the base radius of the cycloid in the described step 60 is the twice of large thin-wall element strait flange width.

5. as having the cast gate method for designing of the large thin-wall element die cast of strait flange as described in the claim 4, it is characterized in that: the import of cycloid shape described in the step 60 running channel adopts the built-up type structure to process.

6. as having the cast gate method for designing of the large thin-wall element die cast of strait flange as described in the claim 4, it is characterized in that: total gate area is to calculate according to formula A=m/ ρ vt in the step 10, the method that total gate area is decomposed each cast gate is to be increased progressively successively to the centre by two ends according to total cast gate number, and increasing progressively on the adjacent linear size is no more than 15% rule and carries out; A represents total gate area in the formula, and m represents the quality of molten metal of ingate, and ρ represents the density of melt, and v represents injection speed, and t represents loading time.

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