HOLLOW MOLD

Provided is a hollow mold which can improve the manufacturing efficiency for a hollow mold including a protrusion. Ventilation duct 3 (hollow mold) includes main body part 20 including hollow part 30 therein, and protrusion 33 protruding outward from main body part 20. End surface 51 of main body part 20 and end surfaces 53 and 55 of protrusion 33 are flush with each other. A cutting operation is linearly performed along the end portion of main body part 20 to the end portion of protrusion 33 in plan view, whereby removal of burr 61 of protrusion 33 to form the end surface is efficiently performed.

CROSS REFERENCE TO RELATED APPLICATIONS

Japanese Patent Application No. 2017-003921 filed on Jan. 13, 2017, including description, claims, drawings, and abstract the entire disclosure is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a hollow mold. More specifically, the present invention relates to a hollow mold which is formed by blow molding of a resin.

BACKGROUND ART

Conventionally, hollow molds which are formed by blow molding of a resin are publicly known (see, for example, PTL 1).

The hollow mold disclosed in PTL 1 is a defroster duct. The defroster duct is integrally formed with a main body part, and a plurality of attaching portions (protrusions) provided at the front end of the main body part. The attaching portion is formed in a rectangular shape in plan view so as to protrude forward along the surface direction of the top surface of the main body part.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

Here, when molding the defroster duct by blow molding, it is necessary to form a portion including a burr in the attaching portion and thereafter remove the burr with a cutter by an operator for the purpose of integrally molding the main body part with the attaching portion protruding from the peripheral portion of the main body part, for example.

However, the burr of the peripheral portion of the attaching portion is removed with a cutter as follows. First, the cutter is advanced in the horizontal direction along the front end of the main body part; then, the orientation of the cutter is changed by 90° (right angle) at the root of the attaching portion so as to move the cutter forward; then, the orientation of the cutter is changed by 90° at the front end corner of the attaching portion so as to advance the cutter in the horizontal direction along the front end of the attaching portion; then, the orientation of the cutter is changed by 90° at the corner of the front end of the attaching portion so as to advance the cutter rearward; and then, the orientation of the cutter is changed by 90° at the attaching portion so as to advance the cutter along the front end of the main body part.

As described above, when the burr is cut off from the peripheral portion of the attaching portion with a cutter, the cutter is required to be moved rightward and leftward in the rectilinear movement in two-dimension, and therefore it is disadvantageously difficult to remove the burr at the peripheral portion of the attaching portion with high accuracy and high speed.

To solve the above-described problems, an object of the present invention is to provide a hollow mold which can improve the manufacturing efficiency for a hollow mold including a protrusion.

Solution to Problem

To solve the above-described problems, a hollow mold according to the embodiment of the present invention includes: a main body part having a hollow shape; and a protrusion protruding outward from the main body part. The main body part includes an end surface, and the protrusion includes an end surface, the end surface of the main body part and the end surface of the protrusion being flush with each other.

Advantageous Effects of Invention

In the hollow mold, the end surface of the main body part and the end surface of the protrusion are flush with each other. Accordingly, the cutting operation is performed by linearly moving the cutter along the end portion of the protrusion from the end portion of the main body part in plan view, thus improving the efficiently of the operation of removing the burr of the protrusion to form the end surface. In this manner, the manufacturing efficiency for a resin hollow mold including a protrusion is improved.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention is described in detail below with reference to the accompanying drawings.

As illustrated inFIG. 1, an instrument panel not illustrated in the drawing is arranged in the front part of the interior of an automobile. Inside the instrument panel, defroster duct1, ventilation duct3(hollow mold) and steering hanger beam5, which is partially illustrated for description, extend along the horizontal direction (vehicle width direction).

Defroster duct1supplies, from a defroster opening of a front end portion of the top surface of the instrument panel, air-conditioning wind for removing inner fogging of a windshield and a side window glass near a side mirror not illustrated in the drawing. Ventilation duct3(hollow mold) is integrally blow-shaped with defroster duct1by use of a resin such as polypropylene. Ventilation duct3(hollow mold) sends and supplies air-conditioning wind that is output from a vertical surface of the instrument panel into the vehicle interior. Steering hanger beam5is manufactured by press forming, welding, casting and the like by use of a metal such as iron and magnesium, or by injection molding with polyamide resin added by use of glass fiber, or the like. In addition, as described later, steering hanger beam5includes first locking projection7, and steering hanger beam5and ventilation duct3are coupled to each other when first locking projection7is locked at protrusion33of ventilation duct3.

To be more specific, as illustrated inFIG. 2, second locking projection9and first locking projection7protruding forward are provided at a front part of steering hanger beam5. First locking projection7extends upward from the front part of steering hanger beam5, and is provided with a bifurcated nail part at the upper end portion thereof. That is, cutout part15is formed at a center portion in the horizontal direction of the upper end portion thereof, and thus bifurcated nail part13is formed. Protrusion33of ventilation duct3is fit in cutout part15of bifurcated nail part13. In addition, second locking projection9holds the front surface of ventilation duct3. First locking projection7and second locking projection9hold ventilation duct3in such a manner as to sandwich ventilation duct3from the front side and the rear side. It is to be noted that a pair of left and right ribs11are formed along the vertical direction on the rear surface of first locking projection7.

In main body part20, first resin member21disposed on the rear side and second resin member23disposed on the front side form inner hollow part30. Specifically, a parison in the form of a tube composed of a molten resin is sandwiched with a metal mold in the blow molding, and thus the opposing parts of the parison are partially brought into contact with each other in a linear shape and coupled to each other, and then, air is jetted thereto so as to form main body part20having hollow part30therein. To be more specific, main body part20is formed in a closed cross sectional structure with rear surface25disposed on the rear side, bottom surface27disposed on the lower side, front surface31disposed on the front side, and top surface29disposed on the upper side. Then, the upper end portion of rear surface25of first resin member21and the front end portion of top surface29of second resin member23are joined to each other in an abutting state in the blow molding, and thus flange22extending obliquely upward is formed.

Protrusion33protrudes to the upper side, which is the direction intersecting top surface29of main body part20. Protrusion33includes a pair of vertical wall surfaces43and upper bottom surface41. Vertical wall surfaces43extend upward, which is the direction intersecting top surface29of main body part20, and are separated from each other in the horizontal direction. Upper bottom surface41couples the upper ends of vertical wall surfaces43in the horizontal direction. End surfaces53and55of vertical wall surfaces43and upper bottom surface41are formed in a U-shape in front view. Thickness T2of vertical wall surface43is smaller than thickness T1of main body part20. It is to be noted that end surface51of main body part20and end surfaces53and55of protrusion33are formed in a straight line in plan view as illustrated inFIGS. 1, 3, and 4.

Next, a procedure of removing burr61of flange22in intermediate product103which is removed from a metal mold after blow molding is completed is described.

As illustrated inFIG. 5, cutting line CL, which is a virtual chain double-dashed line, is set along the longitudinal direction of flange22(the horizontal direction in the state where it is disposed in a vehicle). As illustrated inFIGS. 6 and 7, by linearly moving cutter63in the arrow C direction along cutting line CL, burr61can be removed.

First, by linearly moving cutter63along cutting line CL of flange22of main body part20, the portion other than flange22except for protrusion33can be removed. Here, since protrusion33protrudes upward in such a manner as to intersect top surface29of main body part20, cutting line CL of protrusion33and cutting line CL of flange22of main body part20are set as a straight line in plan view. Accordingly, when removing burr61of protrusion33, burr61can be removed with cutter63without stopping cutter63or changing the orientation of cutter63as in the removal of burr61of flange22of main body part20.

Next, the operation and the effect of the present embodiment are described below.

Ventilation duct3(hollow mold) according to the present embodiment includes main body part20including hollow part30therein, and protrusion33provided at an end portion of main body part20so as to protrude in the direction intersecting top surface29of main body part20. End surface51of main body part20and end surfaces53and55of protrusion33are formed in a straight line in plan view. Here, the “end portion” means the joining part of the resin except for flange22in intermediate product103.

In this manner, in ventilation duct3, end surface51of main body part20and end surfaces53and55of protrusion33are formed in a straight line in plan view. In other words, as viewed from the upper side in the UPR direction inFIG. 3, end surfaces51,53and55form a straight line. Accordingly, in plan view, by a cutting operation of linearly moving cutter63along flange22formed from the end portion of main body part20to the end portion of protrusion33, burr61of protrusion33can be removed to form end surfaces51,53and55. In view of this, the manufacturing efficiency for a resin hollow mold including protrusion33is improved.

That is, in the conventional hollow mold, protrusion33is protruded from the end portion of main body part20in plan view, and consequently, when removing burr61of the end portion of protrusion33, it is necessary to turn cutter63rightward and leftward in the rectilinear movement in two dimension.

By contrast, in the present embodiment, it is not necessary to turn cutter63rightward or leftward in the rectilinear movement in two-dimension, and it is only necessary to linearly move cutter63in plan view, whereby the ease of removal of a burr is significantly increased.

Since end surfaces53and55of protrusion33are formed in a U-shape in front view, the cross-sectional area of the portion removed by cutter63is small in comparison with the case of solid protrusion233(seeFIG. 9). Accordingly, in the case of U-shaped protrusion33, the difference between main body part20and protrusion33in resistance force exerted on cutter63in removal of burr61is small in comparison with the case of solid protrusion233. Accordingly, cutter63can be smoothly moved from the end portion of main body part20to the end portion of protrusion33.

Protrusion33includes a pair of vertical wall surfaces43separated from each other in the extending direction of main body part20, and upper bottom surface41coupling the upper ends of vertical wall surfaces43, and the thickness T2of vertical wall surface43is smaller than thickness T1of main body part20.

Accordingly, the difference in the resistance force exerted on cutter63in removal of burr61between main body part20and protrusion33is further reduced. Accordingly, cutter63can be further smoothly moved from the end portion of main body part20to the end portion of protrusion33.

In addition, the method of cutting burr61of ventilation duct3(hollow mold) according to the present embodiment is a method of cutting burr61integrally formed at an end portion of ventilation duct3made of a resin. Ventilation duct3includes main body part20including hollow part30therein, and protrusion33provided at an end portion of main body part20so as to protrude in the direction intersecting top surface29of main body part20, and cutting line CL set at the end portion of main body part20and cutting line CL set at the end portion of protrusion33are formed in a straight line in plan view. End surfaces53and55of protrusion33and end surface51of main body part20are formed to be flush with each other by linearly moving cutter63from the end portion of main body part20to the end portion of protrusion33along cutting line CL in plan view to remove burr61of the end portion of protrusion33and flange22of main body part20.

Since burr61of protrusion33can be removed by a cutting operation of linearly moving cutter63from the end portion of main body part20to the end portion of protrusion33, the manufacturing efficiency for a hollow mold including protrusion33is improved.

That is, in the present embodiment, cutting line CL set at the end portion of main body part20and cutting line CL set at the end portion of protrusion33are formed in a straight line in plan view. Accordingly, it is not necessary to turn cutter63rightward or leftward in the rectilinear movement in two-dimension, and it is only necessary to linearly move cutter63in plan view, whereby the ease of removal of a burr is significantly increased.

In the method of removing burr61of ventilation duct3(hollow mold) according to the fourth aspect, the end portion of protrusion33is formed in a U-shape in front view.

Since the end portion of protrusion33is formed in a U-shape in front view as described above, the cross-sectional area of protrusions33and233removed with cutter63is largely different from the case of solid protrusion233(seeFIG. 9). Accordingly, in the case of U-shaped protrusion33, the difference in the resistance force exerted on cutter63in removal of burr61between main body part20and protrusion33between main body part20and protrusion33is small in comparison with the case of solid protrusion233. Accordingly, cutter63can be smoothly moved from the end portion of main body part20to the end portion of protrusion33.

In the method of removing burr61of ventilation duct3(hollow mold) according to the fifth aspect, the end portion of protrusion33is composed of a pair of vertical wall surfaces43separated from each other in the extending direction of main body part20and upper bottom surface41coupling the upper ends of vertical wall surfaces43, and the thickness T2of vertical wall surface43is smaller than thickness T1of main body part20.

Since thickness T2of vertical wall surface43is smaller than thickness T1of main body part20as described above, the difference in the resistance force exerted on cutter63in removal of burr61between main body part20and protrusion33is further reduced. Accordingly, cutter63can be further smoothly moved from the end portion of main body part20to the end portion of protrusion33.

It is to be noted that the present invention is not limited to the above-described embodiments, and various modification may be made based on the technical ideas of the present invention.

For example, as illustrated inFIG. 8, thickness T3of vertical wall surfaces153and157of protrusion133and thickness T1of top surface29of main body part20may be equal to each other. Since thickness T3of vertical wall surfaces153and157of protrusion133is greater than thickness T2of vertical wall surface43of protrusion33, the strength of protrusion133is greater than that of protrusion33.

In addition, as illustrated inFIG. 9, protrusion233may be formed in a rectangular planar shape, not the U-shape. In this case, the height (thickness) of protrusion233is set to T4, and thickness T4is greater than thickness T1. It is to be noted that height (thickness) T4of protrusion233is equal to the height of protrusion33and protrusion133.

REFERENCE SIGNS LIST