CN116037801A - Concave rib and mouth part rotary shrinkage forming method of cup body - Google Patents

Abstract

The invention discloses a rotary shrinkage forming method for concave ribs and a mouth part of a cup body, which comprises the following processing steps: the water expansion, the rotary shrinkage, the header cutting and the thread rolling are carried out by adopting a conventional die, the manufacturing cost and the material cost of the water expansion die are reduced, marks are not generated on the cup blank after the water expansion, and the quality is ensured; adopting a rotary shrinkage die to form the concave ribs and the shrinkage openings in the second step, reducing the working procedures, and having high processing efficiency and stable quality; solves the problems existing in the prior art.

Description

Concave rib and mouth part rotary shrinkage forming method of cup body

Technical Field

The invention belongs to the technical field of manufacturing and processing of water cups, and particularly relates to a rotary shrinkage forming method for concave ribs and mouths of a cup body.

Background

As shown in fig. 1, in order to give more shapes to the water cup, some products are made with concave ribs (ring grooves) on the surface of the water cup; in the prior art, water expansion molding is generally adopted in the industry, and because the water pressure is not high enough, the concave rib is mostly large circular arc, which is not beautiful enough, and the concave rib is required to be shaped and cleaned into the expected concave rib after the water expansion molding, so that the manufacturing process is many, and the production efficiency is not high; in addition, there are also the following drawbacks: the water expansion concave rib molding has higher requirement on a water expansion die and poor output; because the concave ribs are inward, the problem that demolding is difficult to achieve after water expansion is caused, the water expansion die is required to be of a double-opening Ha Fumo structure (the water expansion die is complex), namely, a movable half block (sliding block) is required to be arranged on the water expansion die at the position from the concave ribs to the cup mouth, so that after water expansion, a cup body can be taken out, due to the fact that the half block is arranged, the cavity of the water expansion die is poor in integrity (gaps are reserved between parts) due to too many parts, obvious marks are reserved on the surface of the cup body close to the half block after water pressure molding, and the produced cup body is poor in appearance.

Disclosure of Invention

The invention aims to provide a concave rib and mouth part rotary shrinkage forming method of a cup body, which has the advantages of simplified process, high efficiency and stable quality.

In order to achieve the above purpose, the present invention adopts the following technical scheme.

The rotary shrinkage forming method for the concave ribs and the mouth parts of the cup body is characterized by comprising the following processing steps:

step one: water swelling

Taking a circular tube with preset length, putting the circular tube into a water expansion die of water expansion equipment, and performing water pressure molding to enable the circular tube to be water-expanded into a cup body blank to form a head part, a shoulder part and a cup body;

step two: spin-shrinking

The rotary compression adopts a rotary compression mould, and comprises a connecting flange fixed on a rotary power device of the equipment and a mould rod fixed on the connecting flange; the die rod is characterized in that a fixed block is arranged on a step on the outer side of the top of the die rod, a die core extending outwards is arranged in a blind hole in the center of the top of the die rod, a pressing block is arranged at the top of the die core, and the pressing block, the die core and the die rod are fixedly connected through bolts; a top head fixedly connected with the equipment lifting mechanism is arranged above the pressing block and used for controlling die opening and die closing;

the top surface of the fixed block is flush with the top surface of the die rod to form a sliding surface, the outer side of the upper section of the fixed block is a concave table, and the outer side of the lower section of the fixed block is flush with the die rod;

the upper section of the outer side of the pressing block is a round straight section, the lower section of the pressing block is a conical section which is respectively matched with the head and the shoulder of the cup body blank, and an accommodating space is arranged between the bottom surface of the pressing block and the sliding surface;

the demolding mechanism comprises at least 3 equal parts of an outer sliding block and is movably arranged in the accommodating space inside and outside; the inner slide block is arranged between the outer slide block and the mold core, and the outer side surface of the inner slide block and the inner side surface of the outer slide block are inclined surfaces matched with each other; at least 3 ejector rods which are uniformly arranged in the circumferential direction are vertically movably arranged in the through holes of the pressing block, the ejector rods are longer than the through holes, and the lower ends of the ejector rods are abutted against the top surface of the inner sliding block; the demoulding elastic ring is arranged in the groove at the outer side of the outer sliding block and provides elastic restoring force for inward contraction of the outer sliding block;

the specific steps of the spin-shrinking are as follows:

s1: in the mold opening state, sleeving the cup body blank on a mold, wherein the shoulder part of the cup body blank is limited by the conical surface section of the pressing block downwards;

s2: starting the equipment lifting mechanism, pressing the jacking rod by the jacking head under the action of the equipment lifting mechanism, pressing the inner slide block to outwards expand under the action of the inclined plane, and forming a ring groove formed by the outer slide block and the concave table together into a concave rib for forming, wherein the round straight section of the pressing block is used for rotary shrinkage forming of the head;

s3: starting a device rotating mechanism, enabling the die and the cup body blank to rotate under the action of the device rotating mechanism, feeding the cup body blank to a preset position and a head part of the cup body by a rotary shrinkage cutter wheel, enabling concave ribs and the head part to be formed in a rotary shrinkage mode, enabling the diameters of the concave ribs and the head part on the cup body to reach preset sizes to match with the cup cover, and enabling welding seams at the head part and the concave ribs to be smooth; wherein, the order of the concave rib and the head part rotary shrinkage molding can be changed;

s4: the rotary cutter wheel is retracted, the rotation of the equipment rotating mechanism is stopped, the equipment lifting mechanism is lifted, the top head moves away from the pressing block, the top rod is not stressed any more, the outer sliding block is retracted inwards under the action of the demoulding elastic ring, the outer side surface of the outer sliding block is not protruded out of the concave table, the inner sliding block moves upwards under the action of the inner inclined surface of the outer sliding block, the top end of the inner sliding block extends out of the top surface of the pressing block, at the moment, the outer sliding block does not clamp the concave rib of the cup blank any more, and the cup blank can be taken down to finish demoulding;

step three: cutting head

Cutting off the redundant part of the head of the cup body blank horizontally by using cutting equipment to enable the head to reach the preset length, so as to form a cup opening;

step four: rolling thread

And (5) carrying out thread rolling processing on the cup mouth by using thread rolling equipment to obtain threads for being screwed with the cup cover.

By adopting the technical scheme, the water expansion is carried out by adopting a conventional die, the manufacturing cost and the material cost of the water expansion die are reduced, marks are not generated on the cup blank after the water expansion, and the quality is ensured; the rotary shrinkage die is adopted, so that the concave rib forming and the mouth rotary shrinkage can be simultaneously processed, smooth demolding is realized, the working procedure is shortened, the processing efficiency is high, and the quality is stable; solves the problems existing in the prior art.

Preferably, a gap is arranged between the mold core and the blind hole of the mold rod for placing a demolding spring, and elastic force is provided for the upward movement of the inner slide block.

By adopting the technical scheme, the demoulding spring is arranged, so that the inner slide block can rapidly move upwards during demoulding, and the demoulding efficiency and quality are ensured.

Preferably, the plug is formed by contracting the lower part of the main body of the plug inwards, and a first step surface is formed between the plug and the main body; when the mold is closed, the plug-in part is inserted into the head of the cup blank for limiting radial shaking of the cup blank, and the first step surface is matched with the conical surface section of the pressing block for limiting the jumping of the cup blank in the up-down direction.

By adopting the technical scheme, the cup blank can be prevented from moving in disorder in the processing process, stable rotation is ensured, and further the processing quality is ensured.

Preferably, the bottom surface of the plug-in connection part is provided with a guide part in a downward protruding way, and the top surface of the pressing block is correspondingly provided with a guide groove.

By adopting the technical scheme, the plug and the pressing block can be ensured to be concentric, and further the rotation stability of the die and the cup blank is ensured.

Preferably, the bottom surface of the pressing block is provided with a first groove, and the pressing block is sleeved on the top of the mold core through the first groove; the bottom surface of briquetting still is equipped with the second recess for increase the stroke distance of interior slider.

By adopting the technical scheme, the first groove can ensure that the connection between the mold core and the pressing block is more stable; the second groove ensures that the inner slide has sufficient space to move upwards.

Preferably, the ejector rod is in an inverted T shape, and the T-shaped head is arranged between the inner slide block and the pressing block and used for limiting the ejector rod to be outwards separated from the through hole; the upper surface of the inner slide block is provided with a groove for accommodating the T-shaped head.

By adopting the technical scheme, the ejector rod can not deviate from in the processing process, and the T-shaped head is accommodated by arranging the groove on the inner slide block, so that the influence of the T-shaped head on the space for reducing the upward movement of the inner slide block can be avoided.

Preferably, the materials of the mold core, the pressing block, the fixed block, the outer sliding block and the inner sliding block are Cr12 mold steel.

By adopting the technical scheme, the Cr12 die steel is used as the material of the parts, so that the service life of the parts can be prolonged, and the replacement cost of the damaged die is reduced.

Preferably, the material of the elastic demolding ring is cowhells.

By adopting the technical scheme, the TPU cowhells for the demolding elastic ring are made of better wear resistance and elasticity.

Compared with the prior art, the invention has the beneficial effects that: by adopting the technical scheme, the water expansion is carried out by adopting a conventional die, the manufacturing cost and the material cost of the water expansion die are reduced, marks are not generated on the cup blank after the water expansion, and the quality is ensured; adopting a rotary shrinkage die to form the concave ribs and the shrinkage openings in the second step, reducing the working procedures, and having high processing efficiency and stable quality; solves the problems existing in the prior art.

Drawings

FIG. 1 is a schematic diagram of the steps of the molding method of the present invention.

Fig. 2 is a schematic sectional view of the open state of the rotary shrinkage mold in the second step.

Fig. 3 is a schematic sectional view of the mold clamping state of the rotary shrinkage mold in the second step.

Fig. 4 is a schematic cross-sectional view of the compact.

Description of the embodiments

In order to make the technical scheme of the present invention clearer, the present invention will be described in detail with reference to fig. 1 to 4. It should be understood that the detailed description and specific examples, while indicating the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

The invention relates to a method for rotationally shrinking concave ribs and a mouth part of a cup body, which is shown in figure 1 and comprises the following specific steps:

step one: the water expansion, taking a circular tube 100 with a preset length, putting the circular tube 100 into a water expansion die of water expansion equipment, and forming the circular tube into a cup blank by water pressure molding to form a head 101, a shoulder 102 and a cup body 103;

step two: placing the cup blank on a rotary shrinkage die, starting equipment to enable the die to be clamped and fix the cup blank, enabling a rotary power device of the equipment to start to enable the die to rotate to drive the cup blank to rotate, enabling a necking wheel to sequentially and respectively approach to a preset position of the cup body 103 or the head 101 to carry out rotary shrinkage, and enabling concave ribs 104 on the cup to be rotary-shrunk and enable the diameter of the head 101 to reach a preset size to be matched with a cup cover; after the rotary shrinkage, the welding seams at the head 101 and the concave ribs 104 are smooth, so that the problem that the welding seams are difficult to process in the subsequent polishing process is avoided; the screwing-shrinking sequence of the head 101 and the concave rib 104 can be changed; the process can finish the head 101 and the concave rib 104 simultaneously in one procedure, has high processing efficiency and stable quality, and can avoid the defect that the concave rib is stamped when the water expansion processing is performed while the water expansion die structure is conventional;

step three: cutting the head, namely horizontally cutting off the redundant part of the head 101 of the cup body blank by using cutting equipment, so that the head 101 reaches a preset length to form a cup opening 105;

step four: the threads 106 for screwing with the cup cover are formed by thread rolling on the cup opening 105 by thread rolling equipment.

The rotary shrinkage die used in the method comprises a connecting flange 1 fixed on a device rotary power device and a die rod 2 fixed on the connecting flange, wherein a die core 3 extending outwards is arranged in a blind hole in the center of the top of the die rod 2, a pressing block 4 is arranged at the top of the die core 3, and a plug 7 fixedly connected with a device lifting mechanism is arranged above the pressing block 4; the pressing block 4, the mold core 3 and the mold rod 2 are fixedly connected through bolts; the step on the outer side of the top of the die rod 2 is provided with a fixed block 5, the fixed block 5 is flush with the top surface of the die rod 2 to form a sliding surface, the upper end of the outer side of the fixed block 5 is provided with a concave table 51, and the outer side of the lower end of the fixed block is flush with the die rod 2; the upper section of the outer side of the pressing block 4 is a circular straight section, the lower section of the pressing block 4 is a conical section which is respectively matched with the head 101 and the shoulder 102 of the cup body blank, the diameter of the circular straight section is smaller than the inner diameter of the head 101 after the head is rotationally contracted, a containing space is formed between the bottom surface of the pressing block 4 and the sliding surface, a first groove 41 is further formed in the bottom surface of the pressing block 4, and the pressing block 4 is sleeved on the top of the mold core 3 through the first groove 41; the demoulding mechanism 6 comprises an outer sliding block 61, an inner sliding block 62, an ejector rod 63 and a demoulding elastic ring 64; the outer slide block 61 is at least 3 divided equally and is movably arranged in the accommodating space between the bottom surface of the pressing block 4 and the sliding surface inside and outside; the inner slide block 62 is arranged between the outer slide block 61 and the mold core 3, the outer side surface of the inner slide block 62 and the inner side surface of the outer slide block 61 are inclined surfaces matched with each other, under the matching of the inclined surfaces, the outer slide block 61 is contracted inwards to enable the inner slide block 62 to move upwards, and the inner slide block 62 is pressed to move downwards to force the outer slide block 61 to expand outwards; at least 3 push rods 63 which are uniformly arranged along the circumferential direction are vertically movably arranged in the through holes 43 of the pressing block 4, the push rods 63 are longer than the through holes 43, and the lower ends of the push rods 63 are in contact with the top surface of the inner slide block 62; the demolding elastic ring 64 is arranged in the groove at the outer side of the outer sliding block 61 and provides elastic restoring force for the inner shrinkage of the outer sliding block 61, and the material of the demolding elastic ring is cowhells (TPU), so that the cowhells are wear-resistant, high in elasticity and suitable.

As shown in fig. 2, the plug portion 72 is formed by contracting the lower part of the main body 71 of the plug 7, and a first step surface is formed between the plug portion 72 and the main body 72; during die assembly, the plug-in portion 72 is inserted into the head portion 101 of the cup blank to limit radial shaking, and the first step surface and the conical surface of the pressing block 4 cooperate to limit the runout of the cup blank in the up-down direction.

As shown in fig. 2, in order to ensure concentricity between the plug 7 and the press block 4 during mold clamping, a guide portion 73 is provided to protrude downward from the bottom surface of the insertion portion 72, and a guide groove 44 is provided to correspond to the top surface of the press block 4.

As shown in fig. 2, in the mold opening state, the plug 7 is separated from the pressing block 4, the ejector rod 63 is not stressed any more, at this time, the outer slide block 61 is contracted inwards and kept under the action of the demolding elastic ring 64, and the outer side surface of the inner slide block 62 is not protruded out of the concave table 51, so that the cup blank is conveniently taken and placed; the inner slide 62 moves up to drive the ejector rod 63 to move up and the upper end of the ejector rod extends out of the top surface of the pressing block 4.

As shown in fig. 3, in the mold closing state, the top 7 is pressed down, the upper end of the top rod 63 extending out of the top surface of the pressing block 4 is forced to move down, so that the inner slide block 62 moves down, the outer slide block 61 expands outwards, and at this time, the annular groove formed by the outer slide block 61 and the concave table 51 is a cavity formed by concave ribs.

Because the mold core 3, the pressing block 4, the fixed block 5, the outer sliding block 61 and the inner sliding block 62 are in a sliding friction state in the use process of the mold, cr12 mold steel is adopted as the materials of the components in order to prolong the service life of the components. For example, the fixing block 5 and the mold core 3 can be integrally formed with the mold rod 2 in the actual use process, but the fixing block 5 and the mold core 3 are designed into independent parts and adopt Cr12 mold steel in consideration of service life and replacement cost.

As shown in fig. 4, in order to secure the travel distance of the inner slide 62 moving up and down, the bottom surface of the pressing block 4 is further provided with a second groove 42.

In order to ensure that the ejector rod 63 is not easily dropped out during production, the ejector rod 63 is designed in an inverted T shape, and a T-shaped head is interposed between the inner slide 62 and the press block 4 for restricting the ejector rod 63 from being pulled out from the through hole 43. Based on this, the upper surface of the inner slide 62 is provided with a groove for accommodating the T-shaped head, which prevents the T-shaped head from affecting the movable stroke of the inner slide 62.

In order to ensure that the inner slide 62 can move upwards smoothly during demolding, a gap is arranged between the mold core 3 and the blind hole of the mold rod 2 for placing the demolding spring 65, and the demolding spring 65 provides elastic restoring force for the upward movement of the inner slide 62.

The specific mode of using the die in the second step is as follows:

s1: in the mold opening state, sleeving the cup blank on a clamp, wherein the shoulder 102 of the cup blank is limited downwards by the conical surface section of the pressing block 4;

s2: starting the equipment lifting mechanism, wherein the plug 7 moves downwards under the action of the equipment lifting mechanism, the guide part 73 is inserted into the guide groove 44 to be matched with the pressing block 4 so as to ensure that the plug 7 and the pressing block 4 are concentric, the bottom surface of the inserting part 72 presses the ejector rod 63 to move downwards until the bottom surface of the inserting part 72 is in contact with the top surface of the pressing block 4, at the moment, in a die assembly state, the inserting part 72 is inserted into the head 101 of the cup blank, and the cup blank is limited in the radial direction and the circumferential direction so as to prevent shaking or jumping; the ejector rod 63 drives the inner slide block 62 to move downwards so as to enable the outer slide block 61 to move outwards and form a ring groove with the concave table 51 for forming the concave rib 104; the round straight section of the pressing block 4 is used for rotationally shrinking and forming the opening 101;

s3: starting a device rotating mechanism, enabling the die and the cup body blank to rotate under the action of the device rotating mechanism, and enabling the rotary shrinkage cutter wheel 8 to feed the cup body blank to the preset position of the cup body 103 and the head 101 to be rotationally shrunk, so that the concave ribs 104 and the head 101 are rotationally shrunk and formed, and the rotary shrinkage molding sequence of the concave ribs 104 and the head 101 can be changed;

s4: the rotary cutter wheel 8 is retracted, the rotation of the equipment rotating mechanism is stopped, the equipment lifting mechanism is lifted, the top head 7 is moved away from the pressing block 4, the top rod 63 is not stressed any more, the outer slide block 61 is contracted inwards under the action of the demolding elastic ring 64, the inner slide block 62 is moved upwards under the double action of the inner inclined surface of the outer slide block 61 and the elastic force of the demolding spring 65, so that the top rod 63 is moved upwards, the upper end of the inner slide block extends out of the top surface of the pressing block 4, at the moment, the concave rib 104 of the cup blank is not clamped by the outer slide block 61 any more, the cup blank can be taken down, and demolding is completed.

Claims (8)

1. The rotary shrinkage forming method for the concave ribs and the mouth parts of the cup body is characterized by comprising the following processing steps:

step one: water swelling

Taking a circular tube (100) with a preset length, putting the circular tube into a water expansion die of water expansion equipment, and utilizing water pressure molding to enable the circular tube to be water-expanded into a cup body blank to form a head (101), a shoulder (102) and a cup body (103);

step two: spin-shrinking

The rotary compression adopts a rotary compression mould, and comprises a connecting flange (1) fixed on a rotary power device of equipment and a mould rod (2) fixed on the connecting flange (1); a fixed block (5) is arranged on the step at the outer side of the top of the die rod (2), a die core (3) extending outwards is arranged in a blind hole at the center of the top of the die rod (2), a pressing block (4) is arranged at the top of the die core (3), and the pressing block (4), the die core (3) and the die rod (2) are fixedly connected through bolts; a plug (7) fixedly connected with the equipment lifting mechanism is arranged above the pressing block (4) and used for controlling die opening and die closing;

the top surface of the fixed block (5) is flush with the top surface of the die rod (2) to form a sliding surface, the outer side of the upper section of the fixed block is provided with a concave table (51), and the outer side of the lower section of the fixed block is flush with the die rod (2);

the upper section of the outer side of the pressing block (4) is a round straight section, the lower section of the pressing block is a conical section, the pressing block is respectively matched with the head (101) and the shoulder (102) of the cup body blank, and an accommodating space is formed between the bottom surface of the pressing block (4) and the sliding surface;

the demolding mechanism (6) comprises an outer sliding block (61) which is at least 3 equal parts and is movably arranged in the accommodating space inside and outside; the inner slide block (62) is arranged between the outer slide block (61) and the mold core (3), and the outer side surface of the inner slide block (62) and the inner side surface of the outer slide block (61) are inclined surfaces which are matched with each other; at least 3 ejector rods (63) which are uniformly arranged in the circumferential direction are vertically movably arranged in the through holes (43) of the pressing block (4), the ejector rods (63) are longer than the through holes (43), and the lower ends of the ejector rods are in contact with the top surface of the inner sliding block (62); the demolding elastic ring (64) is arranged in the groove at the outer side of the outer sliding block (61) and provides elastic restoring force for inward contraction of the outer sliding block (61);

the specific steps of the spin-shrinking are as follows:

s1: in the mold opening state, the cup body blank is sleeved on the mold, and the shoulder (102) of the cup body blank is limited downwards by the conical surface section of the pressing block (4);

s2: starting the equipment lifting mechanism, pressing down the jacking rod (63) by the jacking head (7) under the action of the equipment lifting mechanism, pressing the inner slide block (62) to outwards expand the outer slide block (61) under the action of the inclined plane, and forming a ring groove formed by the outer slide block and the concave table (51) together for forming the concave rib (104), wherein the round straight section of the pressing block (4) is used for rotary shrinkage forming of the head part (101);

s3: starting a device rotating mechanism, enabling a die and a cup body blank to rotate under the action of the device rotating mechanism, feeding the cup body blank to a preset position of a cup body (103) and a head (101) by a rotary shrinkage cutter wheel (8), enabling a concave rib (104) and the head (101) to be formed in a rotary shrinkage mode, enabling the concave rib (104) on the cup body to be formed and the diameter of the head (101) to reach a preset size to be matched with a cup cover, and enabling welding seams at the positions of the head (101) and the concave rib (104) to be smooth; wherein, the order of the concave ribs (104) and the head (101) which are formed by rotary shrinkage can be changed;

s4: the rotary cutter wheel (8) is retracted, the rotation of the equipment rotating mechanism is stopped, the equipment lifting mechanism is lifted, the ejector head (7) is moved away from the pressing block (4), the ejector rod (63) is not stressed any more, the outer sliding block (61) is contracted inwards under the action of the demolding elastic ring (64) to enable the outer side surface of the ejector rod to be not protruded out of the concave table (51), the inner sliding block (62) is moved upwards under the action of the inner inclined surface of the outer sliding block (61) to enable the ejector rod (63) to be moved upwards and enable the upper end of the inner sliding block to extend out of the top surface of the pressing block (4), at the moment, the outer sliding block (61) is not clamped with the concave rib (104) of the cup blank any more, and the cup blank can be taken down to finish demolding;

step three: cutting head

Cutting off the redundant part of the head (101) of the cup body blank horizontally by using cutting equipment, so that the head (101) reaches a preset length to form a cup opening (105);

step four: rolling thread

A thread (106) for screwing with the cup cover is processed by thread rolling on the cup opening (105) by thread rolling equipment.

2. The method for rotationally shrinking the concave ribs and the mouth of the cup body according to claim 1, which is characterized in that: a gap is arranged between the mould core (3) and the blind hole of the mould rod (2) for placing a demoulding spring (65) to provide elastic force for the upward movement of the inner slide block (62).

3. The method for rotationally shrinking the concave ribs and the mouth of the cup body according to claim 1, which is characterized in that: the lower part of the main body (71) of the plug (7) is contracted inwards to form an inserting part (72), and a first step surface is formed between the inserting part (72) and the main body (71); when the mold is closed, the plug-in part (72) is inserted into the head part (101) of the cup blank to limit radial shaking of the cup blank, and the first step surface is matched with the conical surface section of the pressing block (4) to limit the jumping of the cup blank in the up-down direction.

4. A method for rotationally shrinking a concave rib and a mouth of a cup body according to claim 3, wherein the method comprises the following steps: the bottom surface of the inserting part (72) is provided with a guide part (73) in a downward protruding way, and the top surface of the pressing block (4) is correspondingly provided with a guide groove (44).

5. The method for rotationally shrinking the concave ribs and the mouth of the cup body according to claim 1, which is characterized in that: the bottom surface of the pressing block (4) is provided with a first groove (41), and the pressing block (4) is sleeved at the top of the mold core (3) through the first groove (41); the bottom surface of briquetting (4) still is equipped with second recess (42) for increase the stroke distance of interior slider (62).

6. The method for rotationally shrinking the concave ribs and the mouth of the cup body according to claim 1, which is characterized in that: the ejector rod (63) is in an inverted T shape, and a T-shaped head is arranged between the inner slide block (62) and the pressing block (4) and used for limiting the ejector rod (63) to be outwards separated from the through hole (43); the upper surface of the inner slide (62) is provided with a groove for accommodating the T-shaped head.

7. The method for rotationally shrinking the concave ribs and the mouth of the cup body according to claim 1, which is characterized in that: the mold core (3), the pressing block (4), the fixed block (5), the outer sliding block (61) and the inner sliding block (62) are made of Cr12 mold steel.

8. The method for rotationally shrinking the concave ribs and the mouth of the cup body according to claim 1, which is characterized in that: the demoulding elastic ring (64) is made of cowhells.

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