A production process of a car sound insulation mat

Abstract

The application discloses a production process of a car sound insulation pad, which comprises the following steps: S1: polyester polymer is put into a corresponding processing machine, the processing machine temperature is set to 245-255 DEG C, and then flocculent fiber is prepared; the flocculent fiber is put into a carding machine, low-speed carding is conducted on the flocculent fiber, polyester fiber cotton is prepared, the polyester fiber cotton is put into a forming compressor, and then the polyester fiber cotton is compressed and formed; and then polyacrylate is evenly applied on both sides of the polyester fiber cotton, and the base cloth is prepared; S2: styrene copolymer, rubber, polyethylene, ore powder, a stabilizer and a foaming agent are uniformly mixed in a mixing machine, and the weight proportions of the parts relative to the styrene copolymer are 1, 10%-15%, 5%-10%, 1%-5%, 2%-5% and 2%-3% in sequence, and then the mixed coating is prepared. The application has low production cost, the material is relatively environment-friendly, the smell is relatively small compared with the EVA-made sound insulation pad, the quality is light, and the application is more in line with the pursuit of environment-friendly light weight.

Description

Technical Field

[0001] This invention relates to the field of automotive sound insulation pad manufacturing technology, and more particularly to a manufacturing process for automotive sound insulation pads. Background Technology

[0002] In recent years, with the improvement of people's living standards and the gradual enrichment of their material lives, automobiles, as an important means of transportation, have entered thousands of households. Among them, car sound insulation pads can be applied to various parts of the car, such as the engine compartment, passenger compartment, and trunk, and have the characteristics of shock absorption, sound absorption, and heat insulation. In an era that pursues high performance, environmental protection, lightweight, and comfort, car interiors have become an important factor for people to consider when choosing and purchasing cars.

[0003] Currently, the production process for automotive sound insulation pads generally uses heavy materials such as EVA as the main material. Corresponding wrapping layers are applied to both sides of the sound insulation pad, and then the material is cut and pressed into shape to produce the automotive sound insulation pad. This production method uses EVA as the main material, resulting in sound insulation pads with a strong odor, heavy weight, and unsatisfactory sound insulation effect, which contradicts the pursuit of environmental protection and lightweighting, and affects the user experience in the later stages. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the problems existing in the manufacturing process of a current automotive sound insulation pad, the present invention is proposed.

[0006] Therefore, the purpose of this invention is to provide a manufacturing process for automotive sound insulation pads, which is applicable to solving the problems of sound insulation pads made with EVA as the main material having a strong odor, heavy weight, and unsatisfactory sound insulation effect, which contradicts the pursuit of environmental protection and lightweighting, and affects the user experience in the later stages.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a manufacturing process for automotive sound insulation pads, comprising the following steps:

[0008] S1: The polyester polymer is put into the corresponding processing machine, and the processing machine temperature is set to 245 degrees Celsius and 255 degrees Celsius to prepare flocculent fibers. Then the flocculent fibers are put into a carding machine and carded at low speed to prepare polyester fiber cotton. The cotton is then put into a molding compressor to press and shape the polyester fiber cotton. Finally, polyacrylate is evenly coated on both sides of the polyester fiber cotton to prepare the base fabric.

[0009] S2: Prepare styrene copolymer, rubber, polyethylene, mineral powder, stabilizer and foaming agent and mix them evenly in a mixer. The weight ratio of each part relative to styrene copolymer is 1, 10%-15%, 5%-10%, 1%-5%, 2%-5% and 2%-3% respectively to achieve the preparation of mixed coating.

[0010] S3: Apply the mixed coating prepared in step S2 evenly to both sides of the base fabric, and then place the base fabric with the mixed coating applied into the drying chamber, controlling the temperature of the drying chamber between 170 degrees Celsius and 180 degrees Celsius.

[0011] S4; Take out the dried and shaped base fabric, apply adhesive to the base fabric, and then attach the film paper and aluminum foil to the base fabric in sequence. After pressing and shaping by the bonding equipment, the sound insulation pad can be obtained.

[0012] S5: Place the sound insulation pad prepared in the above steps on the cutting table and use a water jet cutter to cut the sound insulation pad to the specified specifications.

[0013] As a preferred embodiment of the production process of the automotive sound insulation pad described in this invention, in step S3, the base fabric after coating is dried in the drying chamber for 2 to 5 minutes.

[0014] In a preferred embodiment of the manufacturing process of the automotive sound insulation pad described in this invention, the thickness of the adhesive is between 0.2mm and 0.3mm, and the film paper is located on the side of the base fabric away from the aluminum foil.

[0015] As a preferred embodiment of the manufacturing process for an automotive sound insulation pad according to the present invention, the bonding equipment includes:

[0016] The main unit includes a worktable and multiple sets of support ears fixedly mounted on the worktable. The worktable is rotatably connected to a lead screw, and the support ears have semi-circular grooves that match the lead screw. The top end of the lead screw extends upward through the upper side wall of the support ear, and a lifting nut is threaded onto the lead screw. A pressure roller is provided between each set of support ears. One end of the pressure roller is rotatably connected to the side wall of one of the lifting nuts. The lifting nut is vertically slidably connected to the support ear. A micro motor is fixedly mounted on the end of the other lifting nut near the pressure roller. The output shaft of the micro motor is fixedly connected to the pressure roller.

[0017] The deburring unit includes two sets of dust collection boxes symmetrically arranged above the workbench, with the dust collection boxes located between multiple sets of support ears. The lower side wall of each dust collection box is fixedly connected to the workbench by multiple sets of evenly distributed first telescopic columns. Each first telescopic column is fitted with a corresponding first spring. Multiple sets of evenly distributed vibrating forks are fixedly connected to the inner wall of one side of the dust collection box, and a fluff rod is fixedly connected to the end of the vibrating fork away from the side wall of the dust collection box. A glass tube slides and rubs against the outside of the fluff rod. The end of the glass tube away from the fluff rod is fixedly connected to the inner wall of the dust collection box by a corresponding second telescopic column. A second spring is fitted on the second telescopic column. Multiple sets of evenly distributed dust suction holes are opened on the side of the dust collection box near the center of the workbench, and a discharge plate is opened on the side wall of the dust collection box.

[0018] As a preferred embodiment of the manufacturing process of the automotive sound insulation pad described in this invention, the main unit further includes multiple sets of fine adjustment components, and the fine adjustment components include an adjustment rod and a first bevel gear fixedly connected to the adjustment rod. The adjustment rod is rotatably connected to a corresponding support ear. A rotating rod is fixedly connected to the top of the lead screw, and a second bevel gear meshing with the first bevel gear is fixedly sleeved on the rotating rod.

[0019] As a preferred embodiment of the production process of the automotive sound insulation pad described in this invention, each of the pressure rollers is slidably fitted with an adjusting cylinder, and each adjusting cylinder is fixedly connected to a limiting ear on the side away from the supporting ear, and a positioning bolt is threadedly connected to the side wall of the adjusting cylinder, the positioning bolt passing through the adjusting cylinder and abutting against the side wall of the pressure roller.

[0020] As a preferred embodiment of the production process of the automotive sound insulation pad described in this invention, each of the micro motors is fixedly fitted with a protective cover, and the output shaft of the micro motor passes through the protective cover, and the surface of the pressure roller is roughened and polished.

[0021] As a preferred embodiment of the manufacturing process of the automotive sound insulation pad described in this invention, each of the dust extraction holes is configured in a trumpet shape, and the diameter of the opening at one end of the dust extraction hole near the center of the workbench is larger than the diameter of the opening at the other end of the dust extraction hole.

[0022] The beneficial effects of this invention are as follows: This invention uses polyester polymers as the main material for making automotive sound insulation pads. Polyester polymers are widely available, have low production costs, and are relatively environmentally friendly. Compared with sound insulation pads made of EVA, they have a relatively lower odor and are lighter in weight, which is more in line with the pursuit of environmental protection and lightweighting. By using film paper, aluminum foil, and sound insulation cotton in the later stage, the sound insulation effect of the prepared automotive sound insulation pad is improved, thereby improving the driving experience of users.

[0023] While the micro motor drives the pressure roller to press the raw materials of each layer of the sound insulation pad, the telescopic column will cause the dust collection box to vibrate. The tuning fork in the dust collection box will then cause the fluff rod to vibrate. The fluff rod will move against the glass tube through friction, and the glass tube will become charged. This will absorb the dust such as burrs, fibers and powder on the surface of the sound insulation pad raw material, effectively solving the problem that these dust and fibrous materials float in the air and induce respiratory infections in workers. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0025] Figure 1 This is a schematic diagram of the overall process for manufacturing an automotive sound insulation pad according to the present invention.

[0026] Figure 2 This is a schematic diagram of the installation structure of the workbench, pressure rollers, and dust collection box of a bonding equipment for the production process of automotive sound insulation pads proposed in this invention.

[0027] Figure 3 This is a schematic diagram of the fine adjustment unit structure of a bonding equipment for the production process of automotive sound insulation pads proposed in this invention.

[0028] Figure 4 This is a schematic diagram of the installation structure of the pressure roller, micro motor, and adjusting cylinder of the bonding equipment for the production process of automotive sound insulation pads proposed in this invention.

[0029] Figure 5 This is a schematic diagram of the cooperation structure between the lifting nut, rotating rod and second bevel gear in the bonding equipment of the automotive sound insulation pad production process proposed in this invention.

[0030] Figure 6 This is a schematic diagram of the internal structure of the dust collection box of the bonding equipment for the production process of automotive sound insulation pads proposed in this invention.

[0031] Figure descriptions: 100 Main unit, 101 Workbench, 102 Support ear, 103 Lead screw, 104 Lifting nut, 105 Rotating rod, 106 Fine adjustment component, 1061 Adjusting rod, 1062 First bevel gear, 1063 Second bevel gear, 107 Pressure roller, 108 Adjusting cylinder, 109 Positioning bolt, 110 Protective cover, 111 Micro motor, 200 Deburring unit, 201 First telescopic column, 202 First spring, 203 Dust collection box, 204 Dust suction hole, 205 Vibration fork, 206 Fluffing rod, 207 Glass cylinder, 208 Second telescopic column, 209 Second spring. Detailed Implementation

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0035] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0036] Example

[0037] Reference Figures 1-6 As an embodiment of the present invention, a manufacturing process for automotive sound insulation pads is provided, comprising the following steps:

[0038] S1: The polyester polymer is put into the corresponding processing machine, and the processing machine temperature is set to 245 degrees Celsius and 255 degrees Celsius to prepare flocculent fibers. Then the flocculent fibers are put into a carding machine and carded at low speed to prepare polyester fiber cotton. The cotton is then put into a molding compressor to press and shape the polyester fiber cotton. Finally, polyacrylate is evenly coated on both sides of the polyester fiber cotton to prepare the base fabric.

[0039] S2: Prepare styrene copolymer, rubber, polyethylene, mineral powder, stabilizer and foaming agent and mix them evenly in a mixer. The weight ratio of each part relative to styrene copolymer is 1, 10%-15%, 5%-10%, 1%-5%, 2%-5% and 2%-3% respectively to achieve the preparation of mixed coating.

[0040] S3: The mixed coating prepared in step S2 is evenly applied to both sides of the base fabric. Then, the base fabric with the mixed coating is placed in the drying chamber. The temperature of the drying chamber is controlled between 170 degrees Celsius and 180 degrees Celsius. In step S3, the base fabric is dried in the drying chamber for 2 to 5 minutes.

[0041] S4; Take out the dried and shaped base fabric, apply adhesive to the base fabric, and then attach the film paper and aluminum foil to the base fabric in sequence. After pressing and shaping by the bonding equipment, the sound insulation pad can be obtained. The thickness of the adhesive is between 0.2mm and 0.3mm, and the film paper is located on the side of the base fabric away from the aluminum foil.

[0042] S5: Place the sound insulation pad prepared in the above steps on the cutting table and cut the sound insulation pad to the specified specifications using a water jet cutter. In this invention, polyester polymers are used as the main material for making automotive sound insulation pads. Polyester polymers are widely available, have low production costs, and are relatively environmentally friendly. Compared with sound insulation pads made of EVA, they have a relatively lower odor and are lighter in weight, which is more in line with the pursuit of environmental protection and lightweighting. By using film paper and aluminum foil in conjunction with sound insulation cotton in the later stage, the sound insulation effect of the prepared automotive sound insulation pad is improved, thereby improving the driving experience of users.

[0043] The bonding equipment includes a main body unit 100 and a deburring unit 200:

[0044] The main unit 100 includes a worktable 101 and multiple sets of support ears 102 fixedly mounted on the worktable 101. The worktable 101 is rotatably connected to a lead screw 103, and the support ears 102 are provided with a semi-circular groove matching the lead screw 103. The top end of the lead screw 103 extends upward through the upper side wall of the support ear 102, and a lifting nut 104 is threadedly connected to the lead screw 103. A pressure roller 107 is provided between each set of support ears 102. An adjusting cylinder 108 is slidably sleeved on each pressure roller 107. A limit ear is fixedly connected to the side of each adjusting cylinder 108 away from the support ear 102, and a positioning bolt 109 is threadedly connected to the side wall of the adjusting cylinder 108. The positioning bolt 109 passes through the adjusting cylinder 108 and abuts against the side wall of the pressure roller 107.

[0045] By using a movable adjusting cylinder 108 slidably fitted on the pressure roller 107 in conjunction with the positioning bolt 109, different specifications of sound insulation pad materials can be pressed and formed. This effectively solves the problem that the unevenness of the various layers of sound insulation pad materials during the pressing process affects the quality of subsequent pressing and forming. One end of the pressure roller 107 is rotatably connected to the side wall of one of the lifting nuts 104. The lifting nut 104 is vertically slidably connected to the support ear 102. A micro motor 111 is fixedly installed at the end of the other lifting nut 104 near the pressure roller 107. The output shaft of the micro motor 111 is fixedly connected to the pressure roller 107. Each micro motor 111 is fixedly fitted with a protective cover 110 on its outer side, and the output shaft of the micro motor 111 passes through the protective cover 110. The surface of the pressure roller 107 is roughened by grinding. The protective cover 110 can protect the micro motor 111. The roughening of the surface of the pressure roller 107 can increase the pressing transmission efficiency of the pressure roller 107 on the sound insulation pad, eliminating the need to add a traction device to pull the sound insulation pad material.

[0046] The deburring unit 200 includes two sets of dust collection boxes 203 symmetrically arranged above the workbench 101, with the dust collection boxes 203 located between multiple sets of support ears 102. The lower side wall of each dust collection box 203 is fixedly connected to the workbench 101 via multiple sets of evenly distributed first telescopic columns 201. Each first telescopic column 201 is fitted with a corresponding first spring 202. Multiple sets of evenly distributed vibrating forks 205 are fixedly connected to the inner wall of one side of the dust collection box 203, and a lint rod 206 is fixedly connected to the end of the vibrating fork 205 away from the side wall of the dust collection box 203. A glass tube 207 slides and rubs against the outside of the lint rod 206. The end of 207 away from the fluff rod 206 is fixedly connected to the inner wall of the dust collection box 203 through a corresponding second telescopic column 208. A second spring 209 is sleeved on the second telescopic column 208. Multiple sets of evenly distributed dust suction holes 204 are opened on one side of the dust collection box 203 near the center of the workbench 101. Each dust suction hole 204 is set in a trumpet shape, and the diameter of the opening at one end of the dust suction hole 204 near the center of the workbench 101 is larger than the diameter of the opening at the other end of the dust suction hole 204. The purpose of this setting is to improve the efficiency of the dust suction hole 204 in sucking out dust such as automotive burr fibers. A discharge plate is opened on the side wall of the dust collection box 203.

[0047] The main unit 100 also includes multiple sets of fine adjustment components 106, and each fine adjustment component 106 includes an adjustment rod 1061 and a first bevel gear 1062 fixedly connected to the adjustment rod 1061. The adjustment rod 1061 is rotatably connected to the corresponding support ear 102. A rotating rod 105 is fixedly connected to the top of the lead screw 103. A second bevel gear 1063 that meshes with the first bevel gear 1062 is fixedly sleeved on the rotating rod 105. The diameter of the second bevel gear 1063 is much larger than the diameter of the first bevel gear 1062. The purpose of this setting is to improve the fine adjustment of the vertical height of the pressure roller 107, thereby ensuring the adhesion effect of the car sound insulation pad.

[0048] During use, when the film paper, base cloth, sound insulation cotton and aluminum foil need to be pressed into shape, the sound insulation pad material that needs to be pressed is fed into the gap between the workbench 101 and the pressure roller 107. The adjusting rod 1061 is rotated, the first bevel gear 1062 drives the second bevel gear 1063 to drive the rotating rod 105 to rotate, the lead screw 103 rotates accordingly, and the lifting nut 104 threaded to the lead screw 103 drives the pressure roller 107 to press the sound insulation pad material. Then the micro motor 111 is started, and the output shaft of the micro motor 111 drives the pressure roller 107 to rotate. The pressure roller 107 firmly presses and shapes each layer of the sound insulation pad material on the workbench 101.

[0049] While the micro motor 111 drives the pressure roller 107 to press the raw materials of each layer of the sound insulation pad, the telescopic column 201 will drive the dust collection box 203 to vibrate. The tuning fork 205 in the dust collection box 203 will then drive the fluff rod 206 to vibrate. The fluff rod 206 will move in friction relative to the glass tube 207, and the glass tube 207 will become charged. This will absorb the dust such as burrs, fibers and powder on the surface of the sound insulation pad raw material, effectively solving the problem that these dust and fibrous materials float in the air and induce respiratory infections in workers.

[0050] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A manufacturing process for automotive sound insulation pads, characterized in that, Includes the following steps: S1: The polyester polymer is put into the corresponding processing machine, and the processing machine temperature is set to 245 degrees Celsius-255 degrees Celsius to prepare flocculent fibers. Then, the flocculent fibers are put into a carding machine and carded at low speed to obtain polyester fiber cotton. Then, the polyester fiber cotton is put into a molding compressor to press and shape the polyester fiber cotton. Then, polyacrylate is evenly coated on both sides of the polyester fiber cotton to prepare the base fabric. S2: Prepare styrene copolymer, rubber, polyethylene, mineral powder, stabilizer and foaming agent and mix them evenly in a mixer. The weight ratio of each part relative to styrene copolymer is 1, 10%-15%, 5%-10%, 1%-5%, 2%-5% and 2%-3% respectively to achieve the preparation of mixed coating. S3: Apply the mixed coating prepared in step S2 evenly to both sides of the base fabric, and then place the base fabric coated with the mixed coating into the drying chamber, controlling the temperature of the drying chamber between 170 degrees Celsius and 180 degrees Celsius. S4: Take out the dried and shaped base fabric, apply adhesive to the base fabric, and then attach the film paper and aluminum foil to the base fabric in sequence. After pressing and shaping by the bonding equipment, the sound insulation pad can be obtained. The bonding device includes a main unit (100), which includes a worktable (101) and multiple sets of support ears (102) fixedly mounted on the worktable (101). The worktable (101) is rotatably connected to a lead screw (103), and the support ears (102) are provided with a semi-circular groove matching the lead screw (103). The top end of the lead screw (103) extends upward through the upper side wall of the support ear (102), and a lifting nut (104) is threaded onto the lead screw (103). A pressure roller (107) is provided between each set of support ears (102). One end of the pressure roller (107) is rotatably connected to the side wall of one of the lifting nuts (104). The lifting nut (104) is vertically slidably connected to the support ear (102). A micro motor (111) is fixedly mounted on the other end of the lifting nut (104) near the pressure roller (107). The output shaft of the micro motor (111) is fixedly connected to the pressure roller (107). The bonding device includes a deburring unit (200), which includes two sets of dust collection boxes (203) symmetrically arranged above the workbench (101), and the dust collection boxes (203) are located between multiple sets of support ears (102). The lower side wall of each dust collection box (203) is fixedly connected to the workbench (101) by multiple sets of evenly distributed first telescopic columns (201). Each first telescopic column (201) is fitted with a corresponding first spring (202). Multiple sets of evenly distributed vibrating forks (205) are fixedly connected to the inner wall of one side of the dust collection box (203), and the vibrating forks (205) are... 5) A fluff rod (206) is fixedly connected to one end of the dust collection box (203) away from the side wall. A glass tube (207) slides and rubs against the outside of the fluff rod (206). The end of the glass tube (207) away from the fluff rod (206) is fixedly connected to the inner wall of the dust collection box (203) through a corresponding second telescopic column (208). A second spring (209) is sleeved on the second telescopic column (208). Multiple sets of evenly distributed dust suction holes (204) are opened on one side of the dust collection box (203) near the center of the workbench (101). A discharge plate is opened on the side wall of the dust collection box (203). S5: Place the sound insulation pad prepared in the above steps on the cutting table and use a water jet cutter to cut the sound insulation pad to the specified specifications.

2. The manufacturing process of an automotive sound insulation pad according to claim 1, characterized in that: In step S3, the coated base fabric is dried in the drying chamber for 2 to 5 minutes.

3. The manufacturing process of an automotive sound insulation pad according to claim 1, characterized in that: The adhesive has a thickness between 0.2 mm and 0.3 mm, and the film paper is located on the side of the base fabric away from the aluminum foil.

4. The manufacturing process of an automotive sound insulation pad according to claim 1, characterized in that: The main unit (100) also includes multiple sets of fine adjustment components (106), and the fine adjustment components (106) include an adjustment rod (1061) and a first bevel gear (1062) fixedly connected to the adjustment rod (1061). The adjustment rod (1061) is rotatably connected to the corresponding support ear (102). A rotating rod (105) is fixedly connected to the top of the lead screw (103), and a second bevel gear (1063) that meshes with the first bevel gear (1062) is fixedly sleeved on the rotating rod (105).

5. The manufacturing process of an automotive sound insulation pad according to claim 1, characterized in that: Each of the pressure rollers (107) is slidably fitted with an adjusting cylinder (108). Each adjusting cylinder (108) is fixedly connected to a limiting ear on the side away from the support ear (102). The side wall of the adjusting cylinder (108) is threaded with a positioning bolt (109). The positioning bolt (109) passes through the adjusting cylinder (108) and abuts against the side wall of the pressure roller (107).

6. The manufacturing process of an automotive sound insulation pad according to claim 1, characterized in that: Each of the micro motors (111) is fixedly fitted with a protective cover (110), and the output shaft of the micro motor (111) passes through the protective cover (110). The surface of the pressure roller (107) is roughened and polished.

7. The manufacturing process of an automotive sound insulation pad according to claim 1, characterized in that: Each of the aforementioned suction holes (204) is configured in a trumpet shape, and the diameter of the opening at one end of the suction hole (204) near the center of the workbench (101) is larger than the diameter of the opening at the other end of the suction hole (204).

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