100 Continue
The requestor should continue with the request. The server returns this code to indicate that it has received the first part of a request and is waiting for the rest.
101 Switching Protocols
This means the requester has asked the server to switch protocols and the server is acknowledging that it will do so
102 Processing
As a WebDAV request may contain many sub-requests involving file operations, it may take a long time to complete the request. This code indicates that the server has received and is processing the request, but no response is available yet. This prevents the client from timing out and assuming the request was lost.
200 OK
Standard response for successful HTTP requests. The actual response will depend on the request method used. In a GET request, the response will contain an entity corresponding to the requested resource. In a POST request the response will contain an entity describing or containing the result of the action.
201 Created
The request has been fulfilled and resulted in a new resource being created.
202 Accepted
The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually be acted upon, as it might be disallowed when processing actually takes place.
203 Non-Authoritative Information (since HTTP/1.1)
The server successfully processed the request, but is returning information that may be from another source.
204 No Content
The server successfully processed the request, but is not returning any content.
205 Reset Content
The server successfully processed the request, but is not returning any content. Unlike a 204 response, this response requires that the requester reset the document view.
206 Partial Content
The server is delivering only part of the resource due to a range header sent by the client. This is used by tools like wget to enable resuming of interrupted downloads, or split a download into multiple simultaneous streams.
207 Multi-Status (WebDAV) (RFC 2518 )
The message body that follows is an XML message and can contain a number of separate response codes, depending on how many sub-requests were made.
300 Multiple Choices
Indicates multiple options for the resource that the client may follow. It, for instance, could be used to present different format options for video, list files with different extensions, or word sense disambiguation.
301 Moved Permanently
This and all future requests should be directed to the given URI.
302 Found
This is the most popular redirect code, but also an example of industrial practice contradicting the standard. HTTP/1.0 specification (RFC 1945 ) required the client to perform a temporary redirect (the original describing phrase was "Moved Temporarily"), but popular browsers implemented it as a 303 See Other. Therefore, HTTP/1.1 added status codes 303 and 307 to distinguish between the two behaviors. However, the majority of Web applications and frameworks still use the 302 status code as if it were the 303.
303 See Other (since HTTP/1.1)
The response to the request can be found under another URI using a GET method. When received in response to a PUT, it should be assumed that the server has received the data and the redirect should be issued with a separate GET message.
304 Not Modified
Indicates the resource has not been modified since last requested. Typically, the HTTP client provides a header like the If-Modified
Since header to provide a time against which to compare. Utilizing this saves bandwidth and reprocessing on both the server and client, as only the header data must be sent and received in comparison to the entirety of the page being re-processed by the server, then resent using more bandwidth of the server and client.
305 Use Proxy
The requestor can only access the requested page using a proxy. When the server returns this response, it also indicates the proxy that the requestor should use.
306 Switch Proxy
No longer used.
307 Temporary Redirect (since HTTP/1.1)
In this occasion, the request should be repeated with another URI, but future requests can still use the original URI. In contrast to 303, the request method should not be changed when reissuing the original request. For instance, a POST request must be repeated using another POST request.
400 Bad Request
The request contains bad syntax or cannot be fulfilled. The server didn't understand the syntax of the request.
401 Unauthorized
Similar to 403 Forbidden, but specifically for use when authentication is possible but has failed or not yet been provided. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource. The request requires authentication. The server might return this response for a page behind a login.
402 Payment Required
The original intention was that this code might be used as part of some form of digital cash or micropayment scheme, but that has not happened, and this code has never been used.
403 Forbidden
The request was a legal request, but the server is refusing to respond to it. Unlike a 401 Unauthorized response, authenticating will make no difference.
404 Not Found
The server can't find the requested page. For instance, the server often returns this code if the request is for a page that doesn't exist on the server. The requested resource could not be found but may be available again in the future. Subsequent requests by the client are permissible. No indication is given of whether the condition is temporary or permanent.
405 Method Not Allowed
A request was made of a resource using a request method not supported by that resource; for example, using GET on a form which requires data to be presented via POST, or using PUT on a read-only resource.
406 Not Acceptable
The requested resource is only capable of generating content not acceptable according to the Accept headers sent in the request.
407 Proxy Authentication Required
This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy. The proxy MUST return a Proxy-Authenticate header field containing a challenge applicable to the proxy for the requested resource.
408 Request Timeout
The server timed out waiting for the request.
409 Conflict
Indicates that the request could not be processed because of conflict in the request, such as an edit conflict.
410 Gone
Indicates that the resource requested is no longer available and will not be available again. This should be used when a resource has been intentionally removed; however, it is not necessary to return this code and a 404 Not Found can be issued instead. Upon receiving a 410 status code, the client should not request the resource again in the future. Clients such as search engines should remove the resource from their indexes.
411 Length Required
The request did not specify the length of its content, which is required by the requested resource.
412 Precondition Failed
The server does not meet one of the preconditions that the requester put on the request.
413 Request Entity Too Large
The request is larger than the server is willing or able to process.
414 Request URI Too Long
The URI provided was too long for the server to process.
415 Unsupported Media Type
The request did not specify any media types that the server or resource supports. For example the client specified that an image resource should be served as image/svg+xml, but the server cannot find a matching version of the image.
416 Requested Range Not Satisfiable
The client has asked for a portion of the file, but the server cannot supply that portion (for example, if the client asked for a part of the file that lies beyond the end of the file).
417 Expectation Failed
The server cannot meet the requirements of the Expect request-header field.
418 I'm a teapot
The HTCPCP server is a teapot. The responding entity MAY be short and stout. This code was defined as one of the traditional IETF April Fools' jokes, in RFC 2324, Hyper Text Coffee Pot Control Protocol, and is not expected to be implemented by actual HTTP servers.
422 Unprocessable Entity (WebDAV) (RFC 4918 )
The request was well-formed but was unable to be followed due to semantic errors.
423 Locked (WebDAV) (RFC 4918 )
The resource that is being accessed is locked
424 Failed Dependency (WebDAV) (RFC 4918 )
The request failed due to failure of a previous request (e.g. a PROPPATCH).
425 Unordered Collection (RFC 3648 )
Defined in drafts of WebDav Advanced Collections, but not present in "Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol".
426 Upgrade Required (RFC 2817 )
The client should switch to TLS/1.0.
449 Retry With
A 微软 extension. The request should be retried after doing the appropriate action.
450 Blocked by Windows Parental Controls
A 微软 extension. This error is given when Windows Parental Controls are turned on and are blocking access to the given webpage.
500 Internal Server Error
A generic error message, given when no more specific message is suitable.
501 Not Implemented
The server either does not recognize the request method, or it lacks the ability to fulfil the request.
502 Bad Gateway
The server was acting as a gateway or proxy and received an invalid response from the downstream server.
503 Service Unavailable
The server is currently unavailable (because it is overloaded or down for maintenance). Generally, this is a temporary state.
504 Gateway Timeout
The server was acting as a gateway or proxy and did not receive a timely request from the downstream server.
505 HTTP Version Not Supported
The server does not support the HTTP protocol version used in the request.
506 Variant Also Negotiates (RFC 2295 )
Transparent content negotiation for the request, results in a circular reference.
507 Insufficient Storage (WebDAV) (RFC 4918 )
509 Bandwidth Limit Exceeded (Apache bw/limited extension)
This status code, while used by many servers, is not specified in any RFCs.
510 Not Extended (RFC 2774 )
Further extensions to the request are required for the server to fulfill it.
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改善吹塑件壁厚均匀性的几种方法_js金沙登入网址118
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    改善吹塑件壁厚均匀性的几种方法

    日期:2018-08-13 浏览量:100+

    摘要:1.异型口模


    口模异型化是指挤出机头的口模或芯棒局部位置开设凹槽,增大对应制件...


    1.异型口模


    口模异型化是指挤出机头的口模或芯棒局部位置开设凹槽,增大对应制件拐角处的口模间隙,以增加型坯局部位置的壁厚,得到异型化的凶油盘鬻,弥补吹胀比不一致造成的径向壁厚不均,从而得到壁厚较为均匀的制件。针对性地采用异型口模,并通过多次试模、优化、设计加工出合理的异型口模,可以极大提高制件壁厚分布的均匀性。


    2.轴向壁厚控制技术


    轴向壁厚控制技术的作用是使得挤出的塑料型坯,根据制品不同的吹胀比沿轴向获得不同的厚度,从而保证最终制品有比较均匀的壁厚。它是通过使芯棒或口模根据预设位置作轴向运动而改变机头的开口量,达到改变塑料型坯壁厚的目的。目前中空成形机的储料机头一般都具有轴向型坯控制功能,其控制点从30点到256点不等。


    3.径向壁厚控制技术


    采用轴向壁厚控制技术虽然能改善吹塑制品高度方向上的壁厚分布,但由于其挤出塑料型坯的水平截面仍呈等厚圆形,对部分在径向某一部位有较大吹胀比要求的制品显得仍不是最佳,因此便产生了径向壁厚控制技术。径向壁厚控制技术可以使挤出的凶油盘鬻在所要求的区段内呈非圆截面的变化。径向壁厚程序控制技术发展至今,大致形成了2种典型的设计,一种称为柔性环式,另一种称为口缘修形式。


    (1)柔性环技术


    柔性环式是通过电液伺服控制薄壁挠性环在1个方向或2个对称方向上的变形来改变挤出型坯的厚度。它的特点是无论吹制什么形状的制品,只要口模直径不变,径向控制都能发挥作用。对中空成形塑料型坯径向壁厚控制系统的研制工作,最近在江苏获得了关键性的技术突破。这项控制技术可以实现塑料型坯径向壁厚的多点准确控制,控制点可以方便地实现2~16点控制甚至更多点控制,目前正在产业化中。


    (2)口缘修形技术


    口缘修形是靠修形口模环的上下移动来实现型坯壁厚改变的。与挠性环结构相比,其最大的优点是使用寿命长,加工技术难度低。在某些设计中,口模环的修缘部分做成活动块嵌入式,方便更换,减少更换时的成本。这种形式的设计,还需要进行深入研究,降低成本,加快推广步伐。


    径向壁厚控制技术对于提高大型中空制品的品质是一个有效的方法,还能减轻制品的质量。以200L塑料桶容器为例,至少可节省5%~10%的原料。目前加工一套大型径向壁厚控制装置的附加费用较高,随着径向壁厚控制技术的深入研究和发展,将在更多的大中型挤出吹塑中空成形机上应用。


    轴向壁厚控制与径向壁厚控制的联合作用,可获得最佳的塑料型坯,即可获得更为理想的制品壁厚分布。目前国内多家中空成形机制造厂家可在大型中空成形机上选择配套径向壁厚控制系统。


    (3)型坯温差法


    型坯的变形抗力可用粘度来表示,粘度的大小与其温度的高低有关。型坯温度高,黏度小,变形抗力小,吹塑过程中容易变形,变形量较大;相反,型坯温度低,黏度大,变形抗力大,吹塑过程中不容易变形,变形量较小。在挤出过程中,通过冷却设备强制冷却型坯吹胀比较大的部位,使型坯具有合理的温度梯度。型坯吹胀比较大的部位温度低,粘度增大,变形抗力增大。在自由吹胀阶段,吹胀比较大的部位难于变形,变形量减小,而吹胀比较小的部位变形量增大。当变形量较小部位完成变形,进入约束吹胀阶段,吹胀比较大部位继续变形,直至吹胀成形制件,以此提高制件壁厚分布的均匀性。


    (4)真空吸塑与挤出吹塑相结合


    型坯各部位吹胀比不同导致制品壁厚不均匀。制品的吹胀过程可分为自由吹胀和约束吹胀2个阶段。从压缩空气进入型坯到型坯与模具内壁开始接触为止称为自由吹胀阶段。在这一阶段,型坯具有相同的吹胀比,在各个方向的变形都不受约束,可在萰s金沙登入网址118夥较蚺蛘捅湫危医暇取4有团饔肽>咝颓豢冀哟サ叫团魍耆肽>吣诒谔衔钩浦际嫡徒锥巍T谡庖唤锥危团魍獗砻媸苣>呃淙醋饔茫露认陆担扯仍龃螅湫谓衔眩踔敛辉俦湫危贾轮破繁诤窠洗;没有接触模具型腔的坯料,温度相对较高,粘度较小,变形较为容易,迅速变薄,紧贴模具内表面,导致制品壁厚较小,最终使整个制件壁厚不均匀。如果型坯同时结束自由吹胀,就能得到壁厚完全均匀的制件。使型坯在真空负压的拉力作用下,先向吹胀比较大部位发生变形,然后注入压缩空气,改善型坯各处的吹胀比,成功得到壁厚较为均匀的制件。




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